BIOLOGY INTERNATIONAL The Official Journal of the International Union of Biological Sciences
Editor: John R. Jungck, Department of Biology, Beloit College, 700 College Street, Beloit , WI 53511, USA, e-mail: [email protected]
Associate Editor: Lorna Holtman, Deputy Dean, Zoology Department, University of the Western Cape (UWC), Private Bag X17, Bellville 7535, Republic of South Africa, e-mail: [email protected]
Managing Editor: Sue Risseeuw, Department of Biology, Beloit College, 700 College Street, Beloit , WI 53511, USA, e-mail: [email protected]
Editorial Board
Giorgio Bernardi, Accademia Nazionale delle Scienze, via Peter G. Kevan, Department of Environmental Biology L. Spallanzani 5/a, 00161 Rome, Italy University of Guelph, Guelph, ON N3C 2B7, Canada e-mail: [email protected] e-mail: [email protected]
John Buckeridge, RMIT University School of Civil, Nicholas Mascie Taylor, Department of Biological Environmental and Chemical Engineering, Building 10, Anthropology, University of Cambridge level 12, 376-392 Swanston Street Melbourne e-mail: [email protected] GPO Box 2476V, Melbourne VIC 3001 Australia e-mail: [email protected] Ralf Reski, Head, Plant Biotechnology, Faculty of Biology, University of Freiburg, Schaenzlestrasse 1 Zhibin Zhang, Director, Institute of Zoology, Chinese D-79104 Freiburg Germany Acadmey of Sciences, Beijing 100080, P.R. China e-mail: [email protected] e-mail: [email protected] Lily Rodriguez, Sede Servicio Nacional de Areas Jean-Marc Jallon, Institut de Biologie Animale Naturales Protegidas, Ministerio del Ambiente, Lima 27, Intégrative et Cellulaire (IBAIC), Bât. 446, UPS-Orsay, Peru 91405 Orsay e-mail: [email protected] France e-mail: [email protected] Hussein Samir Salama, National Research Centre, Plant Protection Department, Tahrir Street, Dokki, Annelies Pierrot-Bults, Institute for Biodiversity and 12311 Cairo, Egypt Ecosystems Dynamics, Zoological Museum, University of e-mail: [email protected] Amsterdam, P.O. Box 94766, 1090 GT Amsterdam The Netherlands Nils Chr. Senseth, Centre for Ecological & Evolutionary e-mail: [email protected] Synthesis (CEES), Department of Biology, University of Oslo, P.O. Box 1050, Blindern, N-0316 Oslo, Norway Peter Birò, Balaton Limnological Research Institute e-mail: [email protected] Hungarian Academy of Sciences, Tihany 8237, Hungary e-mail: [email protected] Hiroyuki Takeda, Department of Biological Sciences, Graduate School of Science, University of Tokyo, Hongo Yury Degbuadze, A.N. Severtsov Institute of Ecology and 7-3-1, Bunkyo-ku, Tokyo, 113-0033 Japan Evolution, Russian Academy of Sciences, 33 Leninsky e-mail: [email protected] Prospect, 119071 Moscow V-71, Russia e-mail: [email protected] Jen-Leih Wu, Academia Sinica, n°128, Sec 2, Academia rd, Taipei, Taiwan Raghavendra Gadakar, Center for Ecological Science, e-mail: [email protected] Bangalore 560 012, India e-mail: [email protected] Nathalie Fomproix, IUBS, Bat 442, Université Paris-Sud 11, 91 405 Orsay Cedex, France e-mail: [email protected]
Signed articles express the opinion of the authors and do not necessarily reflect the opinion of the Editors of Biology International. Prospective authors should send an outline of the proposed article to the Editors, with a letter explaining why the subject might be of interest to readers. © 2010 International Union of Biological Sciences ISSN 02532069 Biology International No. 47 (September 2010)
Darwin 200: Evolution in Action
Celebrating Darwin’s 200th Birthday and the 150th Anniversary of the publication of Origin of Species
Editorial: John R. Jungck, Editor 3 “International Union of Biological Sciences BioEd 2009: Darwin 200”
Perspectives: Buckeridge, John. Barnacles, Biologists, Bigots, and Natural Australia 5 Selection…Confound and Exterminate the Whole Tribe! Penny, David. 20 Points on the Structure and Testability of Darwin’s New Zealand 11 Theory. Lockhart, Peter and Claudia Voelckel. Lessons from Darwin’s New Zealand 36 Laboratory. Giordan, André. Teaching and Communicating Evolution: Proposals for Switzerland 40 Innovative Approaches and Didactic Researches. Ross, Pauline M., Charlotte E. Taylor, Chris Hughes, Noel Whitaker, Australia 47 Louise Lutze-Mann, Michelle Kofod, and Vicky Tzioumis. Threshold Concepts in Learning Biology and Evolution. Sterelny, Kim. Human Natures. New Zealand 55 Atchia, Michael. Dodos Don’t Duck: Recent Views on the Life and Mauritius 64 Demise of the Dodo (Raphus cucullatus), in the Context of Natural Selection.
High School Education: Leveque, Guy. Assisting Darwin Digitally. France 67 Lombard, Francois, and Marie-Claude Blatter. Adapting Teacher Training Switzerland 70 to Evolution Research Approaches. Stewart, Jim, Cindy Passmore, and Jennifer Carter. Modeling for USA 78 Understanding in Science Education (Project MUSE : Involving High School Students in Evolutionary Biology with Realistic Problems and Causal Models. Fissenden, Joanna. How to Become Pebbles and Bam Bam (or a practical New Zealand 91 approach to human evolution. Cruickshank, Robert H. Teaching “Tree Thinking.” New Zealand 96 Holtman, Lorna. The Teaching of Evolution in South African Schools: South Africa 102 Challenges and Opportunities.
University Education: Weisstein, Anton. The Case of the Protective Protein: Using a Population USA 109 Genetics Simulation in an Undergraduate Lab Course to Test Hypotheses for the Evolution of an HIV Resistance Allele. Zinoviev, Andrei V. Evolutionary Education: An Example from Russia. Russia 117 Jungck, John R. Evolution in Action: Quantitative Evolutionary Biology USA 121 Education.
Evolutionary Studies Important for Education: Winkworth, Richard C. Darwin and Dispersal. Fiji 139
Cover: The cover art was generated by artist Ann Adams of AdamsDesign especially for IUBS BioEd 2009. Editorial:
International Union of Biological Sciences BioEd 2009: Darwin 200
The International Union of Biological Sciences BioED 2009 brought together an international can safely claim to have been the first community of professionals interested in international conference to celebrate the 200th science, secondary and tertiary education. Since birthday of Charles Darwin on February 12th, 2009 was not only the 200th anniversary of 2009, by virtue of having held its "Darwin 200: Charles Darwin's birth, but also the 150th Evolution in Action" meeting of BioEd 2009 in anniversary of the publication of the "Origin of Christchurch, New Zealand, that is, just across Species," the life and legacy of Charles Darwin the International Date Line. The meeting was was at the heart of the meeting. BioEd 2009 one of the coordinated international events promoted understanding of current research and celebrating the birth of Charles Darwin: education about biodiversity and the importance “Darwin 200 Symposia”. The aim of “Darwin of evolutionary biology in science and society 200 Symposia” was to celebrate the impact of through an international exchange of ideas and Darwin’s ideas on current scientific knowledge, knowledge. It embraced multiple cultural with scientific symposia and satellite meetings perspectives, technological advances, curricular taking place on five continents. These meetings practices and materials, informal education, and were run under the auspices of the International curiosity of the natural world. Union of Biological Sciences (IUBS), the IUBS Commission for Biological Education (CBE), New Zealand offered a wonderful venue because and the United Nations Educational, Scientific it was part of "Darwin's Laboratory," i.e., it was and Cultural Organization (UNESCO). one of the stops of Darwin's circumnavigation of the globe on the H.M.S. Beagle and his The Commission for Biological Education of extensive time in the southern Pacific Ocean; it IUBS was established in the early seventies as has a complex ecosystem that undergoes rapid the Union's educational arm. Its major role is to evolutionary change because of volcanism and formulate, initiate and facilitate effective rapid movement by plate tectonics; it has one of methods of improving education in the the best defined geological sites for studying the biological sciences and allied fields, including K-T boundary; and it is home to some flora and the applications and implications of biological fauna known as living fossils such as the studies. The Commission is also committed to Tuatara. Simultaneous sessions reported on assist in the international dissemination and biodiversity of the Pacific region, the uses of exchange of information about biological evolutionary problem solving in plant and education and it acts in a consultative capacity animal breeding, drug and vaccine development, when appropriate. The local host for the protecting biodiversity and avoiding extinction organization of the meetings was the Allan or impact of invasive species, understanding the Wilson Centre for Molecular Ecology and origins of humans and other species, etc. Evolution, a center of excellence for research in New Zealand. Two Allan Wilson Centre leaders, Delegates from twenty-seven countries Professors Peter Lockhart and David Penny, and participated in the celebration complete with Executive Director Susan Adams (who also is birthday cake, two plays on Darwin's life and Secretary of the IUBS Commission for evolutionary education, and a welcoming dance Biological Education) did a superb job in by Maori performers. A highlight of the social recruiting speakers, raising financial support, programme for Bio Ed 2009 was the premiere arranging logistics, and providing an excellent performance of the play "Collapsing Creation" venue. We are deeply in their debt for all of their which considered the dilemmas that Darwin tremendous efforts. faced in going public about his theory of
Biology International Vol. 47 3 Jungck evolution and how he struggled with Alfred John R. Jungck, Editor Russell Wallace's discovery of the principle of Biology International natural selection. The play was written by Arthur Meek and directed by Steven Whiting. It and was performed at the James Hay Theatre in Christchurch. The stage reconstructed the parlor President, IUBS Commission for of Darwin's home, Down House, and gave an Biological Education intimate portrait of Darwin's conversations with his wife, gardener-co-investigator, and scientific guests who frequently visited Down House. The second play was written by one of New Zealand's foremost novelists, Bernard Beckett, who also is a secondary school biology educator and former scholar-in-residence at the Allan Wilson Centre for Molecular Ecology and Evolution. He led a drama group from Hutt Valley High, Wellington, in a performance of his play entitled "Unnatural Selection", which addressed concerns about evolution from students' perspectives.
This issue of Biology International represents the first issue of the journal under new editorship and the transformation from a newsletter to a peer-reviewed journal. It contains papers from authors from nine different countries and from various disciplines within biology, science education, and levels of schooling. The format of the journal is intended to invite multiple uses because we have also moved from a paid subscription print model to an open access electronic model. Thus, we are hoping that scientists and educators will adopt a Creative Commons approach where they may freely re-use and adapt materials presented here in their research and teaching presentations with full acknowledgement of the source of these materials.
Future issues of Biology International will address special topics that reflect the various special programs of the International Union of Biological Sciences such as biodiversity assessment and inventorying, conservation of marine biodiversity, phylogenetic systematics, bioethics, indigenous knowledge, and invasive species.
Editorial 4 Barnacles, biologists, bigots and natural selection… Confound and exterminat e the whole tribe!
John S. Buckeridge
RMIT University, Melbourne, VIC 3001, Australia
During 1851-1854, Charles Darwin published four comprehensive monographs on living and fossil Cirripedia (barnacles). This work comprises some of his most insightful observations on the nature of organisms, although surprisingly, except for about a dozen brief comments, barnacles are ignored in the seminal 1859 edition of “The Origin of Species by Means of Natural Selection”. This paper briefly examines Darwin’s contribution to cirripedology, and contemplates the level of frustration he experienced with the material he had at hand. It also touches upon some of the big issues facing the biosphere, particularly the deleterious environmental changes that mankind has contributed to, and contemplates the ways we are, and should be, addressing these in biological science curricula. It closes with a reflection upon the secularity of biology, and the importance of ensuring that science is based upon empirical evidence.
Charles Robert Darwin It is the latter that we celebrate this week:1 On the bookcase in my office there are Charles Robert Darwin was born in the portraits of three people. These represent English town of Shrewsbury in the County individuals outside of my immediate world of Shropshire on February 12th, 1809. His that have had an impact upon my work. By parents were the physician Robert Waring “immediate world”, I exclude family and Darwin and Susannah Wedgewood. His teachers – of whom, due to proximity, it is grandfather Erasmus, also a physician, had difficult to assess the real impact. The published on natural systems and these ideas portraits are of Aristotle, Charles Darwin had great impact on the development of and Robert Falcon Scott. Even before I had evolutionary theories. In his autobiography thought of putting these three in frames, I (Darwin, 1887) states that he was an had ventured to publish on each – Aristotle ordinary boy who did not excel at his studies in books and articles concerned with ethics, in school, which were strictly classical. At Scott in the popular press about living in the early age of 16, lack of progress led to polar regions, and Darwin in numerous his being enrolled by his father at Edinburgh scientific papers on the biology, evolution University to study medicine – and this gave and distribution of barnacles. Each him no pleasure. However, things were to individual has strengths and insights that I change in his second year there, when he have found invaluable: The indefatigability of Scott, the wisdom of Aristotle, and the 1 th intellect and curiosity of Darwin. This paper was presented orally on February 12 , 2009 (Darwin’s birthday) as a keynote lecture at the IUBS Darwin 200 Symposium, organized as part of the Biological Education Congress in Christchurch, New Zealand. Biology International Vol. 47 5 Buckeridge met and was able to assist Robert Grant in some eight years devoted to barnacles, and the study of marine life along the Firth of was unable to unravel the group to the level the Forth. Although as a child Darwin was he desired. He started off very fascinated by nature, it was Grant’s enthusiastically, as the following letter to influence and interests in the biology of Dieffenbach testifies: marine invertebrates that galvanized Darwin’s attention. His lack of enthusiasm I have for the present given up Geology, and for medicine then led Darwin’s father to am hard at work at pure Zoology and am transfer him to Cambridge, where he dissecting various genera of Cirripedia, and enrolled in a Bachelor of Arts at Christ’s am extremely interested in the subject… College. Whilst at Cambridge he met and Letter to Ernst Dieffenbach, was befriended by the eminent botanist John 9th April, 1847. Stevens Henslow, upon whose recommendation he was appointed as The aforementioned quote followed his naturalist (and gentleman’s companion) to dissection of Cryptophialus, a minute Captain Robert FitzRoy for an expedition to burrowing barnacle found in the shell of the South America on the HMS Beagle – a Chilean mollusc Concholepas. He found the journey initially planned for two years, but material so fascinating that he expanded his that was to last for five, from 1831-1836. study to include as many different barnacles as he could find. Barnacles were a fortuitous The Beagle years provided Darwin with an choice for Darwin: as recently as 1830 J. extraordinary opportunity to fully indulge in Vaughan Thompson had demonstrated they the natural environment – to attempt to were crustaceans (rather than mollucs), and unravel the relationship between taxa in although many species had been described, order to understand the nature and the systematics were still in a state of progression of life on Earth. He made disarray, providing a wonderful opportunity comprehensive collections of all the marine for a young naturalist to make his mark. The invertebrates that he could, including both fossil and living material. When he returned to England, he spent a decade publishing his observations on geology, palaeontology and the origin of coral reefs. He then turned his studies to marine invertebrates, particularly the cirripedes. Darwin published four monographs on the Cirripedia – fossil pedunculates (1851), living pedunculates (1852), living acorn barnacles (1854) and fossil acorn barnacles (1854). In light of the Charles Darwin, aged 31, state of knowledge when he began, and the by George Richmond (1840). material he had at his disposal, his insights are remarkably incisive, and with some barnacle form is indeed strange and curious exceptions align well with current thinking. (Darwin’s words), and they are widely But surprisingly barnacles are only distributed in all oceans, demonstrating an fleetingly referred to in the Origin of Species extraordinary diversity in adapting to (1859), although the structure of his different substrates and habitats. However systematic taxonomy in his monographs the group provided many more obstacles indicates that he had very clear ideas about than Darwin had anticipated. Later in that the evolutionary phylogeny of the year, he was finding cirripede work very Cirripedia. There are suggestions to explain laborious indeed: this anomalous lapsus – the most likely is his frustration with the group. He had spent I have been getting on wretchedly with the
Barnacles, biologists, bigots and natural selection 6
Barnacles, & have done only two other the fossil cirripedes, which take up more genera. time even than the recent; – confound & Letter to J. D. Hooker, exterminate the whole tribe; I can see no 7th April, 1847. end to my work. Letter to J. D. Hooker, Although it was clear that some colleagues 3rd February, 1850. were concerned about the amount of time he was spending on the barnacles, Darwin was Darwin did persevere, and came through adamant that the work should continue. with a remarkably robust perception of the There has been some conjecture about this systematic taxonomy of cirripedes that has dedication to barnacles (some eight years) – formed the basis of our understanding of the apparently at the expense of the Origin of group for more than 150 years (e.g. Species, with suggestions that he may even Newman, Zullo & Withers, 1969; have procrastinated because of concern Buckeridge, 1983; Newman, 1993; about the religious impact of his “species Buckeridge, 1996; Buckeridge & Newman, theory” on some of his family and friends 2006). Of great systematic import was his (Browne, 1995; Love, 2002). I suspect deduction that balanids (or acorn barnacles) Darwin may well have had these feelings, originated within the pedunculates. Of but perhaps he found the group just too personal interest is Darwin’s uncertainty extraordinarily interesting to forsake: indeed about the correct way to approach that is why the morphology, systematics and taxonomy. Although he was present at the distribution of cirripedes entrance a small presentation of the British Association’s group of biologists to this day. Darwin was “Series of Propositions for Rendering the nonetheless very aware of the importance Nomenclature of Zoology Uniform and the Cirripedia in his formulation of “species Permanent” in 1842, he was sufficiently theory”: concerned about his own work to write to Henslow in 1848 stating: I have not the ..you will perhaps wish my Barnacles & smallest idea whether my names are correct. Species theory al Diabolo [to the Devil] I have sympathy with this, for in the 1850s, together. But I don’t care what you say, my there was no comprehensive International species theory is all gospel. Code of Zoological Nomenclature. Indeed, Letter to J. D. Hooker, even with the code, I struggled to get things 10th May, 1848. right for my barnacle taxonomy in the 1980s! Darwin did make some curious …(you say) that you care more for my mistakes, such as the degree of thoracican species work than for the Barnacles; now segmentation, but as Newman (1993) this is too bad of you, for I declare your observes, these should be seen in the context decided approval of my plain Barnacle work of the day. over theoretical species work, had great influence in deciding me to go on with the In 1864, Darwin was awarded the Royal former & defer my species paper... Society’s Copley Medal for his Letter to J. D. Hooker, contributions to geology and natural history, 12th October, 1849. and in particular for his work on the cirripedes. It is his barnacle work, more than Perhaps not surprisingly, due to the any other, which confirmed his status as a incomplete nature of the fossil record, it was leading biologist and provided the the fossil balanids that were ultimately to framework for his theory of natural give Darwin the most angst (and to instigate, selection. in part, the title of this paper):
I have now for a long time been at work at
Biology International Vol. 47 7 Buckeridge
Global Change accommodate the theory of evolution, That global climate evolves naturally is a although certain fundamentalist groups have given; it is nonetheless clear that never done so. This resistance has been anthropogenic activities are having a poignantly revealed in a preliminary study deleterious effect upon the biosphere and on francophone countries by Clément & that biologists, more than most Quessada (2008), who showed that professionals, have a pivotal rôle in both inculcation of creationist belief within mitigation of negative effects and future science was most likely to occur in countries planning for the sustainable management of with lowest per capita income, where it was natural resources. How humans adjust to the norm. environmental evolution is greatly dependant upon the knowledge base of Evolution and creationism are both theories. society, and this is reflected in the relevant However, all “theories” are not equal, education system i.e. biology curricula and although there are those who, for their own pedagogy at all levels. Problems such as reasons, would wish it so. There are many habitat loss, spread of invasive species, things that we need to understand about our pollution and bio-security are compounded world, and as it was 150 years ago, when by demands of, and advances in genetic Darwin published his work on survival of engineering, conservation, evolution, the fittest, the origin of life must rank high. ecological modeling, molecular biology, It is contended however, that any attempt to systematic taxonomy and medicine. empirically justify creationist theology is Importantly, assessment of effects involves doomed – for by doing so, it is argued that more than just one profession – with broad- creationists would discredit both their faith based, sustainable solutions required to and compromise the aims of science solve most environmental problems; as such, (Buckeridge, 2008). However, it is not it is important to demonstrate how biology solely in poorer countries that creationism is relates to other disciplines such as getting press: On 12 September 2008, the technology, economics and ethics. This must front page of The Times newspaper had the be undertaken in an environment with header “Scientists put case for teaching shrinking budgets and increasingly invasive creationism”. A full article appeared on page occupational health and safety regulations. 3, and proclaimed that leading scientists Darwin opened our minds to the grandeur of were at odds with Government over nature. It is our duty to ensure it survives... religious education. Of considerable an imperative, for biology teachers to significance was the identity of one of these deliver a scientific framework from which scientists, the Reverend Professor Michael effective natural resource management can Reiss, Director of Education at the Royal be achieved is not an option – it is a Society. The following furor resulted in necessity. Reiss resigning, and the Royal Society reaffirming its position that “creationism has Creationism in the Science no scientific basis and should not be part of Curriculum: the science curriculum”. However damage There is grandeur in this view of life... from had been done, with many creationists so simple a beginning endless forms most seeing this as a victory. beautiful and most wonderful have been, and are being, evolved. Darwin (1859) Creationism is irrefutably a belief, and even if it has a taint of bigotry about it, there may Although Darwin personally baulked at well be a place for teaching creationism in challenging Church dogma, he permitted his schools: If it fits the school’s ethos, it is best friend Thomas Huxley to do so on his taught alongside other beliefs as part of the behalf. Over the next few decades, the humanities curriculum. attitude of the established church was to
Barnacles, biologists, bigots and natural selection 8
References or Pedunculated Cirripedes.” Ray Society, London (1851). 400 pp. Browne, E.J. (1995). Charles Darwin Voyaging: A Biography. Volume 1. Darwin, C., (1854). “A Monograph on the Princeton University Press: Princeton. Sub-Class Cirripedia. The Balanidae and Verrucidae.” Ray Society: Buckeridge, J. S. (1983). “The fossil London. 684 pp. barnacles (Cirripedia: Thoracica) of New Zealand and Australia.” New Darwin, C. (1854). “A Monograph on the Zealand Geological Survey fossil Balanidae and Verrucidae of Paleontological Bulletin 50: 1-151. Great Britain.” Palaeontographical Society Monograph 30. 44 pp. Buckeridge, J. S., (1996). “Phylogeny and Biogeography of the Primitive Sessilia Darwin, C. (1859). On the Origin of Species and a consideration of a Tethyan origin by Means of Natural Selection. John for the group.” Crustacean Issues 10: Murray, London. 255-267. A.A. Balkema Publishers: Rotterdam. Darwin, F. (Ed.) (1887). The life and letters of Charles Darwin, including an Buckeridge, J. S. and W. A. Newman. autobiographical chapter. Volumes I- (2006). “A revision of the Iblidae and III. John Murray: London. the pedunculate barnacles (Crustacea: Cirripedia: Thoracica), including new Love, A. C. (2002). “Darwin and the ordinal, familial and generic taxa, and Cirripedia Prior to 1846: Exploring two new species from New Zealand the origins of the Barnacle and Tasmanian waters.” Zootaxa Research.” Journal of the History of 1136: 1-38. Biology 35: 251-289.
Buckeridge, J. S. (2008). “Creationism and Newman, W.A. (1993). “Darwin and Intelligent Design: a critique.” In cirripedology.” In History of Dossier Évolution et créationnisme. Carcinology. (Ed. F. Truesdale). A.A. Natures Sciences Sociétés. 15(4): 405- Balkema: Rotterdam. pp. 349-434. 406. Newman, W.A., V.A. Zullo, & T.H. Clément P. and M.P. Quessada. (2008). Withers. (1969). “Cirripedia. “Creationist conceptions of teachers Treatise on Invertebrate (Primary and Secondary schools Paleontology,” R. C. Moore, (Ed.). teaching biology or language) across Part R, Arthropoda 4(1): 206–295. nineteen countries.” Abstracts of the Geological Society of America and International Congress of Zoology, The University of Kansas Press. Paris, France August 26-29th, 2008. p. 109.
Darwin, C. (1851). “A Monograph on the fossil Lepadidae, or pedunculated cirripedes of Great Britain.” Palaeontographical Society Monograph 13. 88pp.
Darwin, C. (1852). “A Monograph on the Sub-Class Cirripedia. The Lepadidae;
Biology International Vol. 47 9 Buckeridge
John Buckeridge is the Head of the School of Civil, Environmental, and Chemical Engineering at RMIT University. He is also Immediate Past President of the International Union of Biological Sciences (IUBS), Chairman of the IUBS Bioethics Committee, Past President of the International Society of Zoological Sciences, and he has acted as a consultant on environmental ethics to UNESCO’s COMEST (World Commission on the Ethics of Scientific Knowledge and Technology). Professor Buckeridge is an Honorary professor at Wismar University, Germany, in recognition of his work in engineering ethics. He has published more than 250 books, journal articles, and reports, in subject areas that include geology, geological engineering, paleobiology, engineering systems, ethics, marine biology, forensics, and natural resources management.
Barnacles, biologists, bigots and natural selection 10
20 Points on the structure and testability of Darwin’s theory
David Penny
Allan Wilson Center for Molecular Ecology and Evolution, Massey University P.O. Box 11,222, Palmerston North, New Zealand, email: [email protected]
Darwin’s theory of evolution is analyzed, firstly as the three major areas of microevolutionary processes, macroevolution, and the sufficiency of microevolutionary processes for macroevolution. The overall theory is then divided into 20 components, each of which has been thoroughly tested. A conclusion is that microevolution is simply inevitable; there is no way that we could stop, for example, the evolution of RNA viruses. Nor do we find well studied areas where microevolution is not able to account for macroevolution, though this is still an active area of research.
Evolution is as fundamental to biology as the It turns out to be very important to understand second Law of Thermodynamics is to the that Charles Darwin started his scientific career physical sciences. In this report I first break the as a geologist in the highly mechanistic tradition theory into three major questions, and then of James Hutton and Charles Lyell (see Herbert analyze these into 20 components; these differ in 2005). Both of these, Hutton in the 1790s (Dean their logical status such as whether they are 1992), Lyell in the 1830s (1830-33), published straightforward empirically based results, to major works in geology and each attempted to conclusions that are derived from some of them. explain past changes to the earth in terms of I will present these 20 points from two time ‘causes’ (mechanisms) that could be studied in perspectives, the first from the mid 19th century the present. Past events had to be explained in when Charles Darwin was developing his full terms of mechanisms that could still be theory, and the other from the present when we measured and tested; examples would include are testing these ideas against current erosion, uplift, volcanism and sea level changes. knowledge. Darwin wrote three books on the geology of the Beagle voyage, joined the geological Society of However, the first step is to briefly cover three London on his return (and was active in the background issues that allow us to get going; society), and his early papers were in geology that the first profession of the young (Barrett 1977). It is this highly mechanistic Charles Darwin was as a geologist who later approach of Hutton and Lyell that Darwin later transferred to biology, secondly some idea of took into biology, and it explains his interests in what we expect of a good scientific theory, and the microevolutionary processes of plant and finally the awareness that the word ‘evolution’ is animal breeders, inheritable variation in used with several different meanings. These help populations, his calculations of the potential understand the reasoning behind the later ideas. increase in numbers of a species, the large number of experiments he carried out (particularly on plants) - generally trying to
Biology International Vol. 47 11 Penny make and test predictions. Darwin wanted his moved towards the ground to its ‘natural place’. mechanism of evolution to be ‘scientific’ - he But how do you measure the property of the considered zoology to still be in a descriptive stone ‘knowing’ it is ‘mostly earth’? How do stage in the mid 1830's. The conclusion is that you measure its ability to ‘sense’ which direction Darwin developed his rigorous method of the ground is? Such ‘explanations’ are certainly scientific reasoning as a geologist and then not independently testable. applied it to biology (Penny, 2009). Geology and biology were not as separate as they are now and An equivalent example in biology are many people studying ‘natural history’ usually had forms of ‘orthogenesis’ that were still popular some expertise in both areas. into the 20th century as an ‘explanation’ for a mechanism of evolution - somehow living Turning from the young Darwin as a geologist to matter has the automatic ability to change the idea of a good scientific theory, perhaps we slowing over long periods of time to a ‘better’ or all have a reasonable idea of what in an ideal ‘improved’ state. But, and it is a big ‘but’, this world we would like of a scientific theory. The would be a property of living systems that ideas would probably include being able to make cannot be measured - pity no one told the horse testable predictions, and that the proposed shoe crab, or the tuatara, or the maidenhair tree mechanisms were able to be evaluated (Ginkgo), or indeed protists and bacteria independently. A major part of the conclusion generally about the theory, they might have kept here is that Darwin’s mechanistic formulation of evolving upwards! the theory of evolution is very close to being in such an ideal world! All aspects have been The third part of the background is the need be subject to testing over and over again– even if careful over the word ‘evolution’, it is used in many biologists today still apparently yearn for biology with several different meanings, some great mythical ‘driving force’ behind including the following. evolution. More on that later. 1) change with time - now in everyday use as, for example, the evolution of the novel, or, Indeed, several early biologists, including the evolution of a solar system, this usage Charles grandfather Erasmus, favored some usually just implies change through time. form of evolution – but were not able to propose 2) the theory of descent, usually an evolutionary any testable mechanism. Initially (the mid to late tree relating species. 1830’s) Darwin could not think of a realistic 3) ‘evolution’ by ‘natural selection’, here we are mechanism to explain the divergences, and distinguishing the pattern of relationships especially the adaptation of each species to its from the mechanism; environment. While looking for a possible 4) mechanism for change - in Darwin's case the mechanism he read very widely. He was processes of natural selection, sometimes influenced by the French philosopher August evolution is used synonymously for natural Comte on what was expected of a good scientific selection; theory, and Comte thought that in the past there 5) sufficiency - are the processes in natural had been a progression of theories before good selection sufficient to account for the scientific hypotheses were proposed. Comte changes? If asked the question', ‘do you imagined an early stage where people suggested ‘believe’ in evolution?’ it is often this that stars were moved across the sky by angels alternative that is intended. (or horses) - for example. At another stage people depended less on external agencies, a As with most words in English (and in other good example is the ancient Greek explanation languages) there is no one ‘correct’ usage, it is for a stone being released from your hand then just necessary to determine in context which falling to the earth. There were four ‘elements’ usage is intended. (earth, air, fire and water), stone was mostly earth, and earth ‘knew’ its place was at the center of the universe and so the stone therefore
20 Points on the structure and testability of Darwin’s theory 12
All populations have the potential for an exponential increase in numbers. This potential to increase in numbers was well- known even before Darwin. The second volume of Lyell's ‘Principles of Geology’ (1831) gave many examples of the potential for rapid increase in numbers of a species, and he takes his information from earlier authors, including authors from Scotland (Hutton), Switzerland (de Candolle) and southern France. However, by
Figure 1. The three major components of Darwin's theory. itself (without considering inherited variability) They are shown with arrows in each direction because they it did not lead to the idea of species changing are mutually supporting in that, for example, the theory of through time. descent is supported by the existence of a mechanism that could lead to species modification and divergence; but the theory of descent has also lead to the search for mechanisms Because of limited resources, some competition that would result in descent with modification. Hypothesis 3 is the one still being debated among scientists (based on is inevitable. Riddiford and Penny, 1984). For most species, the observed numbers, averaged over a number of years is So now we return to consider the overall approximately constant, even though the structure of Darwin’s theory as three major potential for exponential increase in numbers questions (Figure 1), together with some was there. Environmental resources are always implications and conclusions from them. The limited (such as incoming light energy per area first is the proposed mechanism of for plants) and therefore there is intra- as well as microevolutionary processes, and this is divided inter-specific competition for resources. here into 5 components (two population/ ecological, two inheritance/genetics, and then Some of the variability within populations is the conclusion that populations must change inherited. with time. The second major question is about New variability is continuously arising, species changing, and new families, orders and regardless of any ‘needs’ of the organisms. At phyla arising through the long time periods that the time of Charles Darwin biologists did not geologists have inferred is available – this is know the details of genetics, though they usually referred to as macroevolution. Then we certainly did know generally about inheritance. consider the third, more general, question, Perhaps the best explanation of why other whether the processes of microevolution are not biologists did not recognize Mendel’s advance only necessary, but sufficient to account for that turned ‘inheritance’ into ‘genetics’ was that macroevolution. These three major questions are they had thought that inheritance should also followed by some of the consequences of the explain development (see Sandler and Sandler theory. Overall, the analysis considers 20 aspects 1985). The other inhibiting factor for some, but of the theory which will first be outlined briefly not all, biologists was the acceptance of the idea and then each is discussed in more detail. At the of an ‘unchangeable essence’ for a species. Any end there is a brief discussion on some future observed inherited differences, under that developments that we expect. hypothesis, was just deviations from the ideal type, and would eventually be lost. Microevolutionary Processes and Natural Selection Some of this inherited variability can affect The first two points of Darwin’s mechanism are survival and reproduction. ecological/population components, the second This refers to survival and reproduction in the two relate to inheritance, and the fifth integrates present (physical and biological) environment. the two aspects (ecological and genetics) to give The probability of surviving and reproducing the conclusion. can increase or decrease relative to other members of the population. In one sense this
Biology International Vol. 47 13 Penny appears as quite a weak statement – ‘some’ (following Napoleon’s conquests) studied inherited variants, and the ‘probability’ of mummies of animals in Egypt that were about survival and reproduction. But there are large 4000 years old. The mummies of cats, dogs, numbers, and lots of time. crocodiles or ibises (for example) contained animals that looked just like modern species! If Some change in gene frequencies between the world was only around 6000 years old, and generations is inevitable – natural selection. the species 4000 years ago were already fully Processes 1-4 (microevolutionary processes) modern, then it was stretching incredulity to leads to a change between generations in the suggest that all of evolution had occurred in a frequency of different genetic variants, this is mere 2000 years (and by processes that could microevolution. The probabilistic component is scarcely be imagined). emphasized here, and was a novel part of Darwin’s proposed mechanism. As mentioned The principle of divergence – descent with above, there are large numbers and long periods modification of time, and so some change is inevitable. In The splitting of lineages has continued over all addition, it is now emphasized that there is geological time, Thus there is a continuity of continuity of gene frequencies between living forms through geological time and this generations. gives a unity of life in that all living species shared a common ancestor somewhere in the Macroevolution and the theory of descent past. This arises from the processes of with modification. microevolution that were discussed earlier. Species can split into two or more lineages. Traditionally (before about 1700) it was The sufficiency of microevolutionary assumed that life continued to arise processes - Darwinism or actualism. spontaneously, and that some forms of living The processes of microevolution are sufficient to matter (and non-living) could interchange account for macroevolution (though remember (werewolves, for example!). In the early 18th point 20 at the end). century the idea of species having some permanence through time became established The processes of microevolution are sufficient among biologists. However, it was often for macroevolution combined with the ancient Greek idea of This is perhaps a key issue at present. Biologists ‘unchangeable essences’. By accepting that there had accepted that evolution had occurred within were no unchangeable ‘essences’ or ‘forms’ about 10 years of the publication of the origin. allowed evolution to occur and also allowed a We see later that it was much longer (1940s-50s) potential increase in the number of species. before most biologists accepted that microevolutionary processes were necessary for Extinction of species has occurred. evolution. But it has taken longer for biologists It may seem surprising that in the 18th and early generally to accept that there is ‘nothing else’. 19th centuries it was uncertain whether extinctions occurred at all. In medieval times it In particular, microevolutionary mechanisms was assumed that ‘forms’ of life could continue are sufficient for the origin of humans. to generate spontaneously. From the 18th century Perhaps the first was to accept the derivation of onward (when ‘species’ were considered to have humans from the African Great Apes, but continuity through time) it was thought by some Darwin insisted that it had to include our mental that an ideal creation of an ideal creator could powers and language ability, as well as our not, almost by definition, go extinct – after all, it social, religious and ethical systems. The latter was perfect. features are now actively being studied.
A very long time scale is available for evolution. The evidence against long term evolution did look quite strong when French scientists
20 Points on the structure and testability of Darwin’s theory 14
Conclusions, consequences and limitations of plants we could get selection between the sunny the mechanism side and the shady side of the same tree? This The above are the basic mechanisms and would not alter the basic principles. conclusions of Darwin’s mechanism, but a range of consequences are important. There is a strong chance (stochastic) factor in evolution. The Principle of Continuity, “natura non facit This arises in many ways including in mutations saltum”. (origin of inherited variability) and in selection Basically, there is a continuous series of (or lack of it). There are both stochastic and intermediates between generations. This is deterministic factors in evolution. Allowing a often called ‘gradualism’ - a very much major non-deterministic role in evolution was an misunderstood and misleading term that we aspect that was seriously criticized in Darwin's shall see is best avoided because of its time, especially by physicists. Later (last ambiguity. Here we emphasize the continuity century) physicists did adopt probabilistic and overlap of gene frequencies between arguments, though perhaps not acknowledging generations, each change between generations biologists were there first! being in principle reversible. Certainly, the rate of change between generations may be Adaptations and new features. variable, and changes in gene frequency occur The mechanism explains the overall ‘fit’ on a biological/ ecological time scale. The between form, function, and the environment. principle of continuity and reversibility Any slightly improved variant (that was between successive states is fundamental in inherited) that tended to fit the environment many aspects of science. In principle, some better was more likely to survive. This point was non-darwinian theories could still meet the critical to the theory; it explained the apparent requirement for continuity, for example, ‘design’ in nature. Highly ordered structures can orthogenesis (however, it doesn’t have a arise gradually from less ordered states and lead testable mechanism). Darwin frequently used to the origin of new features: orchids can the phrase ‘nature does not make jumps’ eventually evolve from Chlorella-like algae, (natura non facit saltum). This linked his ideas mammals and birds from unicells. Each into other aspects of mathematics and science intermediate form must be beneficial to its (including physics). In mathematics, Leibniz possessor (or at least not be harmful). had used it in the development of calculus (there was continuity between successive points Lack of perfection. during differentiation, for example). Many features are expected to be less than fully perfect for several reasons; constraints from pre- Populations and individuals selection. existing forms, limited genetic variability, Because of the nature of inheritance the benefit conflicting requirements, and all intermediate (or loss) goes primarily to the possessors of a forms must be functional. Natural selection is gene or gene combination. Selection thus expected to lead to local optima, but not generally acts on individuals, and populations necessarily to the global optimum. Examples change in gene frequencies. Any changes are not considered were the explosive increase in in principle ‘for the good of the species’, nor can numbers of some plants and animals introduced the processes of natural selection be oriented to into new lands (the previous inhabitants did not future goals. The processes can certainly lead to appear to be perfectly adapted to their own cooperation both within and between species and environment – though there may be secondary early biologists were well aware of this; reasons such as the invaders escaping their coevolution occurs regularly in nature. Perhaps natural parasites). Similarly, eyes (including this is an area where we have to be a little humans) did not give perfect vision, and males careful – most of the theoretical work has had nipples on their breasts (which were assumed the germ cell/somatic cell distinction unnecessary and therefore imperfect to the that is characteristic of animals. Perhaps with Victorian mind). Surely any competent designer
Biology International Vol. 47 15 Penny would design genetics so that cancers did not modern work (by concentrating on numbers of arise! Adaptation is relative rather than absolute. viable offspring, rather than survival of the original parents) usually treats sexual selection No predetermined pathways of development. as an aspect of natural selection. In contrast, an earlier theory of orthogenesis assumed organisms slowly change through There are other ways to analyze Darwin's theory, predetermined pathways over geological periods Mayr (1985) considered it as five theories which of time. However, under darwinian evolution, if cover much the same ground, and the larger all vertebrates were removed from the earth categories in the present analysis are similar to there is no requirement that identical body plans those of Mayr. What is important here is that the would develop again (this is contingency). This overall theory, together with its consequences, is conclusion reinforces the previous one. Simple relatively complex - even though each physical principles will limit the types of component is relatively quite straight-forward. organisms that evolve, but there are many body Because Darwin considered all the steps is one plans that fit the physical requirements. reason why, qualitatively, his thinking and Evolution can go from less complex to more reasoning was not equaled or surpassed until the complex organisms, but it can also go the other 1930's. way – towards simpler organisms, including parasites (‘reductive’ evolution). What the theory did not explain was the mechanism for the continued generation of No need to postulate a plan, or ultimate cause. variability. Darwin (and others) noted that in This conclusion applies to both organisms and to many plants, sexual reproduction led to more the universe. There is no need for an underlying variability among offspring than did non-sexual ‘purpose’ to living systems, including that the (asexual) reproduction. This observation by world was made for humans ‘to have dominion itself still does not ‘explain’ the diversity but it over’ (see later). The concept of ultimate cause did mean that, in principle, mechanisms must had been very influential in Western thought exist that continue to generate diversity. It was (and perhaps most cultures) at least from the not until this century, after the rediscovery of time of Ancient Greek philosophers, and Mendel’s genetics, that the problem of the origin probably much earlier. Darwin's theory does not of variation could be tackled, and there is still exclude the possibility of purpose in the the fundamental problem of the linkage between universe, only that it is unnecessary to postulate inheritance (genetics) and form (morphology) of it. an organism.
Humans are ‘a part of nature’, ‘not apart from Each of the 20 points will be now expanded and nature’. given some additional explanatory comments. Nature was not created for humans, nor are we Unfortunately it would require at least a book to exempt for the laws of nature. This is a go into full detail as to where the ideas came fundamental change in viewpoint, and is from and how they differed from others at the discussed in more detail later. It is perhaps still a time. sticking point in the modern world. EXPANDED COMMENTS Not all mechanisms are known. The Processes of Natural Selection This is fundamental; there was never a claim that POPULATIONS AND ECOLOGY. we knew all possible mechanisms. Perhaps there is a limitation is that any such new mechanism All populations have the potential for an must be able to be studied in the present (‘causes exponential increase in numbers. now in operation’) – but now there is not much The potential for a continued increase in we can’t study in the lab, in nature, or in the numbers of individuals in a species (plant and computer? Darwin considered sexual selection to animal) had been recognized early by several be different from natural selection though authors, but Malthus in the early 19th century
20 Points on the structure and testability of Darwin’s theory 16 who emphasized it for human populations as There are at least two ways of approaching this well. He had been a controversial figure in the aspect; from the limitation of resources or the early 19th century because he used his average size of most populations staying the calculations to argue that the human population same. This relative constancy of numbers had would inevitably outstrip food resources, and also been discussed at length in the second therefore nothing (according to Malthus) could volume of Lyell's Principles of Geology. Taken prevent human misery. Darwin's family just by itself, it had not led to the idea of any background was radical-liberal and in his change through natural selection. Lyell's main autobiography he almost apologized for even discussion was in terms of competition between reading Malthus. species (he had quoted De Candolle's ‘all plants “In October 1838, that is, fifteen months are at war, one with another’). But as shown in after I had begun my systematic enquiry, I the following quote, Lyell had also recognized happened to read for amusement Malthus on competition within a species. Population, and being well prepared to ‘Unhealthy plants are the first which are cut appreciate the struggle for existence which off by the by causes prejudicial to the species, everywhere goes on, from long-continued being usually stifled by more vigorous observation of the habits of animals and individuals of their own kind. ... In the plants, it at once struck me that under these universal struggle for existence, the right of circumstances favorable variations would the strongest eventually prevails;’ (Lyell, pp. tend to be preserved, and unfavorable ones 55-56). destroyed.”
But while the concept of competition was What Darwin took from Malthus was the combined with the assumption that all mathematical precision that guaranteed, in individuals in a species are ‘essentially’ the principle, the exponential increase in numbers. same, then all members were treated as But by seeing the possibility of ‘improvement’ equivalent and the effects of intra-specific (depending ‘favorable variations would tend to aspects were not recognized. It had been be preserved’) his conclusion was in many ways accepted earlier that selection could remove the opposite of Malthus. Other authors, even some less-fit individuals that deviated from the from the 18th century, knew of the potential for perfect type or essence of the species. The intra- population increase. The second volume of specific variants most different from the original Lyell's ‘Principles’ (1831) gave many examples type would be lost, thus maintaining the species of the potential for rapid increase in numbers of ‘essentially’ unchanged. Consequently, even a species, particularly when introduced into a when selection had been recognized the new area. Like Malthus, these other authors had typological concept of species inhibited thinking not seen the possible implications when about continued evolutionary change from the combined with inheritable variability. original type.
The potential for the exponential increase in a By combining components 1 and 2, Darwin population gave inevitability to this aspect of concluded that intra-specific (as well as inter- Darwin's mechanism - this aspect is basically specific) competition was inevitable in nature. deterministic. This was important in showing Taken by itself, this would not lead to any that at least part of his theory met the change in a species, except perhaps eliminating expectations of scientists in 1830's that science forms that were the most different from the should be deterministic. This aspect of the original type of the species. Combined with the proposed mechanism is completely accepted as idea that species were originally created perfect thoroughly tested gave even more reason not to accept change.
Competition had to be combined with ideas in Because of limited resources, some sections 3 and 4 on inherited variability. competition is inevitable.
Biology International Vol. 47 17 Penny
corner-stone of his theory. Let us remember that the Origin of Species begins with a discussion of variation under domestication.” (Lewontin, 1974, p5).
With molecular data we find we are almost overwhelmed by the amount of genetic variation we can measure – whether in DNA sequences, microsatellites, AFLP, variation in copy number of some genes, etc. Variability is now recognized as universal.
Some of this inherited variability can affect survival and reproduction. Figure 2. Sub-hypotheses of microevolution (the components of Given the view that variability was undesirable, natural selection). The left hand side is based on ecological/ population studies, the right hand side on our knowledge of many authors had recognized that selection inheritance/genetics. Solid boxes are based on observations, those would tend to eliminate these forms; in current with dotted lines are inferences. Several are considered in more detail in the text. terminology this is negative selection. The realization that plant and animal breeders were So next we come to the Genetic Component. able to use the variability to give new breeds of domesticated species allowed Darwin a new Some of the variability within populations is view of this variability, domesticated breeds inherited. were ‘improvements’ (from the human That individuals varied from both environmental viewpoint) so variation was in some sense and inherited differences was well known from ‘natural’ and offered at least the potential for the 17th century, but the variation was often increased survival of some members of the considered unimportant and even undesirable - it population in some environments. A was deviation from the ‘perfect form’ (or qualification could have been made that many essence) of the species. The job of the domestic varieties tended to revert to a more taxonomist was to discover the original perfect natural breed if the plants or animals escaped form being masked by variation. Thus the task from domestication. This did not counter the was to ‘ignore’ the variation, variation was an argument that change was possible (as opposed indication of the imperfection of the world (why to many essentialist views) and the variants an all-powerful Creator would make such an selected could be maintained in a different imperfect world was a difficult question). environment.
“The metaphysical introduction of ideal bodies Darwin also pointed out the that morphological moving in ideal paths, so essential to the changes that occurred, for example in domestic proper development of physics and so dogs, or in the cabbage/cauliflower/broccoli consonant with the habits of thought of the groups were far greater than normally occurred 17th century, was precisely what had to be between genera, even though they (dogs, or destroyed in the creation of evolutionary broccoli and cabbage) were still in the same biology. Darwin rejected the metaphysical species (as judged by interbreeding). object and replaced it with a material one. He Consequently the morphological changes called attention to the actual variation among selected by plant and animal breeders were more actual organisms as the most essential and extensive than occurred between species in illuminating fact of nature. Rather than nature. As we would say now, variability is, regarding the variation among members of the among other things, a resource. It was clearly an same species as an annoying distraction, as a important step to give up the theory of an ideal shimmering of the air that distorts our view of form of a species but it is not clear when Darwin the essential object, he made that variation the
20 Points on the structure and testability of Darwin’s theory 18 did this. Possibly the experience from plant and ‘natural selection leads to a better fit animal breeders was sufficient? between organism and environment’. As short-hand the latter is fine - as long as it is Conclusion from components 1-4. clear it is just that. It is misleading to treat natural selection as if it were almost a thing or Some change in gene frequencies between an object. We say that natural selection doesn’t generations is inevitable – natural selection. “do” anything – it is just the automatic result of Given the background knowledge (components the potential for the increase in numbers of 1-4), it is an inevitable outcome that there offspring, limitation of resources, and normal would, over time, be changes in the population - genetic variability. and that the population could in some sense be more suited to its immediate environment Again, the predictions here have all been (biological and/or physical). This we can call thoroughly tested. Perhaps best known are the natural selection, and would result from (in continued change of RNA viruses, influenza A Lyell’s words) ‘causes now in operation’ - and HIV are two well known ones. For processes which could be studied in the present influenza, the strain used for vaccination is by experiment and observation. This was the changed every 6 months, one for the northern triumph of Darwin's theory - it allowed hemisphere winter, one for the southern. With continuing adjustment to the environment RNA viruses we see evolution in action in real without postulating mysterious, unknown and time, but increasingly we can measure short term unobservable mechanisms (either operating (‘contemporary’) evolution. For example, currently, or at some remote time in the past). Darimont et al. (2009) gives several examples Clearly it required a long time scale, and this where the effects of humans in populations of was still a problem from the knowledge other species is leading to measurable changes. available in the early 19th century. There are other quite different examples; with RNA there is also ‘in vitro’ evolution – There needs to be a word of caution here, the occurring in the proverbial test tube. The starting mechanisms for generation of new inheritable mixture is very large number of different RNA variability were unknown in Darwin’s time, and molecules. This population of RNA molecules this problem was not solved until well after is, for example, passed through a column that Mendel’s laws were rediscovered. Nevertheless, has a compound you require the RNA to bind. it was known in the 19th century that inherited The RNA molecules that bind slightly to this variability did occur, and that it increased after compound are retarded by the column. These sexual reproduction, but not asexual. In addition, RNA molecules are selected and then replicated some of the variability was ‘useful’ - at least for many times by a process that allows some new artificial selection. Consequently, Darwin’s mutants to accumulate. The new population of theory depended only on observable features, RNA molecules is tested again, and the process increases in new inheritable variability which repeated several times. All sorts of new reactions could affect virtually all aspects of an organism. catalyzed by RNA are found; evolution in a test tube, evolution is real. To sum up this section, it is important to note that ‘natural selection’ is the consequence of There is also a well-established area of computer several processes (1-4) and when there is any programming, called either genetic algorithms or ambiguity it is clearer to speak of ‘the processes evolutionary programming. There may be many of natural selection’, rather than just ‘natural variants of a program that have different selection’. In many ways it is more accurate to parameters, and these parameters can change say, for example, randomly (and even have recombination). The ‘the processes of natural selection lead to a program is run many times on different better fit between organism and environment’, problems, the more successful programs can be than duplicated, the less successful variants deleted. Such programs ‘evolve’ to good results, but just
Biology International Vol. 47 19 Penny as with evolution in general, they have no horses and measure them, etc., but we cannot see guarantee of finding the best possible result. or measure the ‘essence’ of a horse. Go Thus standard evolutionary principles can lead Antisthenes! to improvements in the computer program. Thus normal and natural biological populations, RNA As mentioned earlier, given the medieval view viruses, RNA in the test tube, and computer of unchangeable essences, variation within a programs, all demonstrate that the mechanisms species was considered as an undesirable proposed for microevolutionary change work. deviation from the ideal form - though variation The ideas are thus thoroughly tested did not change the essence. Even some early scientifically. (pre-Darwinian) evolutionary theories were affected by the concept of essences in that they Thus a major conclusion is that some continued appear to assume an invisible bond throughout change with time (evolution) is inevitable – there the species (or ‘monad’) so that all members of a is just no way that we can stop evolution. There species would evolve in the same way. Lamarck was the musical of the 1960’s – “Stop the (Burkhardt 1977) did allow some splitting of World, I want to get off”. Sorry, no way! We lineages, but mostly species had arisen can’t stop the world for you to get off, nor can independently by spontaneous generation and we stop evolution. Microevolutionary change is were evolving as a unit. The concept of inevitable. ‘essentialism’ comes up in other aspects of everyday thought, such as Fascism (where The theory of descent - (macroevolution, or imagined ‘race’ is the central issue, in forms of ‘the fact of evolution’). Marxism (with economic class is the ‘essential’ We now turn to long term evolution – factor), and some forms of radical feminism macroevolution. (where gender is the over-riding factor). Perhaps the key point of testability here is that plant and Species can split into two or more lineages. animal breeders, as we saw earlier, had changed Only one point need be made here. It was not domesticated species beyond the diversity of obvious to earlier biologists that a species could genera – eliminating any idea of an split into two or more lineages. An important unchangeable essence of plant or animal inhibitory factor was the ancient Greek concept species. So change beyond the level of species is (from Aristotle and Plato) of the unchanging thoroughly tested scientifically. ‘essence’, ‘type’, or ‘ideal form’ for any class of objects. The essence was, by definition, Extinction of species has occurred. unchangeable. These Greek ideas had been Given the present day recognition that there have integrated into medieval ‘Christian’ theology been massive extinctions of megafauna (and and it was assumed (by definition) that the many other species) over the last 12,000 or more essence or type could not change, let alone split years, it may seem surprising that in the 18th and into two. ‘Christian’ is in quotes because today early 19th centuries it was uncertain whether we often assume that the concept of unchanging extinctions occurred at all. In medieval times essences as being a traditional part of (before species were considered to have Christianity, however it is really a later addition permanence through time) it had been assumed (13th-14th centuries) to Christianity from Greek that all forms of life continued to form thought. Strictly speaking, the early Greeks had spontaneously, ‘from the earth’ for example. a variety of views; it was the ideas of Plato and Thus there was really no question of extinction Aristotle which were adopted by the early- being possible; organisms could regenerate at medieval European theologians. Some Greeks any appropriate time. If all the living forms of a had other views. ‘‘I can see horses, Plato’ said ‘type’ died, it would still be expected (on that Antisthenes, ‘but I nowhere see your ideal view) that new forms would arise spontaneously horse’’ was the retort of another Greek from some appropriate part of the earth. It was philosopher who thought it unnecessary to ‘known’, for example, that the earth or soil in postulate un-seeable ideal forms - we could ‘see’ England was different from that in Ireland -
20 Points on the structure and testability of Darwin’s theory 20 grass snakes developed spontaneously from the automatically change and ‘improve’. ‘Hard-line’ soil in England, but not in Ireland. Case proved! scientists scoffed at such an untestable Consequently we cannot really ‘blame’ earlier mechanism. So even if some scientists were peoples if they hunted an animal to extinction if ‘right’ about species evolving, they were they assumed the animal could regenerate simultaneously ‘wrong’ about how it occurred. spontaneously. Slower growing (‘K-selected’) Pattern and process are both important. species were especially vulnerable to human impacts (Holdaway and Jacomb 2000). From our viewpoint today, the non-evolutionists Cuvier and Lyell had high scientific standards - A different argument against extinctions arose but were willing to put limits on science, outside later in the 18th century after the concept of of which the Creator had a role. Lyell did later biological species had developed. It went (1860s) accept that evolution had occurred. On something like, ‘species are created by an all- the other hand the evolutionists in the late 18th powerful Kind Friendly Creator (KFC) to fit and early 19th centuries were unscientific by our their environment perfectly; surely no perfect standards, because they made no attempt to test work of the Creator will be destroyed, their speculations on mechanisms by which particularly because they fit their environment evolution may have occurred. In modern terms, a perfectly’. Even though remains of unknown theory that claims to explain every conceivable species had been found only as fossils it was still event, really explains nothing (it can’t be possible that living examples would eventually falsified or disproved, a key requirement for a be discovered in unexplored parts of the earth scientific theory). Darwin came from within the (especially in the deep ocean if the fossils were tradition of Lyell and was able to maintain the marine). Another possibility though was that the high scientific standards of only proposing fossil forms still existed in the sense that they mechanisms that could be studied and tested in had changed over time to a species that was no the present. So yes, from the modern viewpoint, longer recognizable as the original fossil. Others the possibility of extinction is so well argued that it was no business of mere mortals to established, that we take it for granted, and work put limits on the Creator - who could do as He or towards its prevention. She pleased. A very long time scale is available for By the early 19th century some naturalists had evolution. accepted the argument of a series of creations, This was still controversial in the early 19th accepting the Creator's divine right to destroy century. By then, most geologists accepted that living things and create new ones, these the world must be older than the 6,000 years that scientists accepted extinction. Scientists such as was proposed by Bishop Ussher and then by the Cuvier and Lyell, though very different in their Vice-Chancellor of Cambridge University views, were anti-evolution but accepted during the mid 17th century. Nevertheless, in the extinction - Cuvier (1817) through catastrophes early 19th century maybe many thought in terms and Lyell through gradual extinctions according of tens to hundreds of thousands of years, rather to ecological laws. Others such as Lamarck (and than tens or hundreds of millions of years. By probably Geoffroy St Hilaire) were pre- about 1840 Lyell, from his Principles of Darwinian evolutionists but apparently denied Geology (1830-3), had convinced most extinction occurred - to Lamarck species geologists that the world was indeed many automatically had the ability to adapt to new millions of years old. Lyell's mechanisms (as conditions. If we couldn't find fossil taxa living with those of James Hutton in the late 18th in the present it was because they had adapted century) required vast time periods to allow for and changed to new conditions and we didn't repeated cycles of geological change by ‘causes recognize them yet. It was difficult for these now in operation’. Nevertheless in the early early evolutionists to accept extinction because editions Lyell did not specify how old he their ‘mechanism’ of evolution was just the thought the earth was. Darwin thought that the (metaphysical) statement that species could mechanisms of evolutionary change (natural
Biology International Vol. 47 21 Penny selection) would require a long time scale of and animals. There were many earlier proposals, hundreds of millions of years. particularly in the 17th to early 19th century (Penny et al. 2003; Stevens 1994) but they The main scientific attack on this very long time differed markedly from the theory of descent. scale started from the 1860's (after the We saw earlier that the real problem of the publication of the Origin of Species) and was relationship of species only became important from the physicists (particularly Lord Kelvin) once species were assumed to have a continuous who argued for a much shorter time scale existence over long periods of time. This is after (though still tens of millions of years) because of the idea of continuous spontaneous generation the argument that can be paraphrased as ‘the sun became improbable (see Oparin 1953; Farley couldn't be that old or it would have run out of 1977), and it was no longer accepted that one oxygen to burn for energy’. The discovery of form of life could ‘transmute’ into a quite radioactivity at the end of the 19th century different form during the lifetime of an allowed the sun a much larger and longer lasting individual. Recall that our definition of a species source of energy, and eventually allowed a as a group of interbreeding individuals seems radioactive dating of the age of the earliest first to have been stated by the late-17th century rocks. The physicist Lord Rutherford, early in English scholar, naturalist and divine, John Ray the 20th century, was apparently the first to (see Raven 1986). His concept of a species is suggest that natural radioactivity could be the similar to ours in that membership of a species source of energy for the sun and that this would was characterized by being born from, mating allow for an older age for the earth. The age of with, and being parents of members of the the earth is now put at around 4500 million years group. ago with the origin of recognizable forms of life possibly occurring by 600-700 million years The most popular form of relationship between later. species for zoologists in the 17th and 18th centuries was the Great Chain of Being. White With the rise of many forms of radioactive Anglo-Saxon males magnanimously appointed dating, especially Potassium /Argon dating for themselves at the top of the Great Chain – at older divergences, there is a lot of independent least of normal biological species - but there information on the age of the geological epochs, were many orders of angels and archangels the subject is completely non-controversial above us, just so that we show a modicum of within science. humility! Many explorers sought to fill the ‘gaps’ by finding new species that filled The principle of divergence – descent with apparent holes in the series. When chimpanzees modification. were first described in detail by Tyson (1699) Darwin considered it a major discovery to they were known as Homo sylvestris (humans of conclude that the evolutionary processes he the forest) and they were important in filling an considered operated ‘without end’. This perhaps apparent gap between the ‘lower humans’ and integrated the natural selection component (5) monkeys. We have already pointed out that the with the previous point of the long time scale. Great Chain of Being could be interpreted as: This appeared to lead naturally to an ‘static’ (species created in their present form); evolutionary tree, but Darwin was always careful degenerating (species degenerating with time); to refer to his theory as ‘descent with or ‘ascending’ (species originally simple and modification’, rather then to emphasize the tree becoming more complex with time). In this latter aspect. Today we are so used to seeing case there was no attempt to give a mechanism relationships between taxa as a tree that we to explain how the increase in complexity forget that, from the time of the ancient Greeks, occurred. it took over two thousand years of studying plants and animals before the tree diagram was Another concept was of an ‘archetype’, the basic proposed in its present form. A tree is not a self plan, idea, or perfect form, which might have evident pattern for relationships among plants been used to design all later species. Whether it
20 Points on the structure and testability of Darwin’s theory 22 had ever existed was unclear. An architect may both chloroplasts and mitochondria. Genes in never have built their ideal house (archetype); higher plants come from three different sources individual designs had to be modified from the (admittedly a long way back) and a network is archetype to take account of the building site, an appropriate model - though in practice each finances, weather conditions and so on. The gene tends to be considered separately and a tree archetype was particularly influential in early drawn from each. Within bacteria there is 19th century zoology when comparative transfer of some genes between bacterial anatomists argued there was a common ground ‘species’ through ‘lateral transfer’ by plasmids plan used for all mammals, another for all and other mechanisms. Lateral transfer could vertebrates, and another for all multicellular happen occasionally within eukaryotes, for animals. On this hypothesis, lions and tigers may example between an insect and its host via be similar not because of common descent parasites. A different kind of case is when there (sharing a common ancestor) but because they is adaptation of a small population (from within were created separately to the same mammalian a larger species) to a new environment, and is plan – and adjusted for the lifestyle of a large difficult to represent this in a standard tree. carnivore in a warm climate. Examples include the origin of polar bears from within brown bears, and some high alpine It was certainly not apparent to scientists in the buttercups in New Zealand which arise 18th and early 19th century that a rooted tree independently from within widely dispersed diagram was the best way of indicating species from lower altitudes. Going back much relationships between species. In all the sciences earlier to the origin of life, the best models we it required major efforts before fundamental have at present assume a large number of small patterns were recognized that allowed the genetic fragments that would continually development of mechanistic hypotheses. For recombine. None of these cases overrides the use example, in astronomy there were ellipses of the tree relationship between eukaryotic describing the movement of planets around the species as being the most useful model. sun. That the planets (the Wanderers) behaved However the model of interbreeding species may differently from the fixed stars was recognized not be so useful outside the sexually reproducing about by 3000 BC, but it took around 4500 years eukaryotic groups, although in this case lateral to find the correct pattern to describe their transfer could be considered equivalent. At this motion - rotating in elliptical orbits around the point we leave macroevolution and start sun, in the same plane and in the same direction. considering microevolutionary processes. In chemistry it was Mendeleev's table that showed the relationship of the chemical DARWINISM OR ACTUALISM. properties of the elements; in geology the importance of matching the coastlines leading to The processes of microevolution are sufficient the ideas of continental drift and plate tectonics. for macroevolution. In all these cases, as well as in using trees for Within science, the first two major sections of relating biological species, the answer seems macro and micro-evolution are now fully ‘obvious’ to us today. In each science it was a accepted; evolution has occurred, and the major achievement to finally recognize the processes of microevolution are necessary for patterns in the data that lead to the knowledge evolution. It is perhaps still a little controversial about the mechanisms (processes) involved. (though decreasingly so) as to whether the mechanisms we are able to study in the present There are many times where a tree will not be a are sufficient to account for past changes. As good model for describing relationships, and a stated above, this question is very different from network (that allows cycles in the graph) is whether we know all the mechanisms - we do required. An obvious case is with plants where not, see later. Rather it is whether studying hybrids are common, though increasingly ‘causes now in operation’ will be sufficient to hybrids are being found among animals. Another explain past changes, or whether we appeal to well studied case is the endosymbiotic origin of some type of mechanism that cannot now be
Biology International Vol. 47 23 Penny studied - and to that extent would be outside the mutations, population increase, and selection can realm of normal science. be shown in the laboratory and in the field. Can it be shown that the processes in Part B are Darwin's theory has often been referred to as sufficient to account for macroevolution? ‘gradualism’, but as we saw above this is both Perhaps a few still advocate some form of ambiguous and misleading. Instead, what is orthogenesis, guided evolution, or important is the continuity between generations - macromutation? The questions now being asked ‘numerous slight successive changes’. Darwin about the sufficiency of evolutionary theory made an extremely bold statement, form the ‘third Darwinian revolution’, the first ‘If it could ever be demonstrated that any two revolutions being the acceptance that complex organ existed which could not evolution had occurred (for biologists, this was possibly have been formed by numerous, mostly in the 1860s and 1870s, Hull et al, 1978), successive, slight modifications, my theory and the second the necessity of microevolution would absolutely break down’ (Darwin, (mostly in the 1940s and 1950s, Mayr and 1859). Provine 1980). Examine this statement carefully; it is continuity, not ‘equal rates’, which Darwin saw as critical to In particular, microevolutionary mechanisms his theory. His claim is still critical to current are sufficient for the origin of humans. work on the sufficiency of microevolutionary This includes their mental powers, language processes. ability, and social, religious and ethical systems. Right from the beginning of his study on the One of the most interesting questions here is origins of species (in the late 1830's) Darwin how to get from the DNA genotype to the included humans in his theory. He made phenotype as actually observed. The discussion extensive notes on humans, including the usually centers on the difference between a development of physical and mental abilities of ‘blueprint’ and a ‘recipe’. In an architectural young babies (his own children), although it was blueprint, for example, there is more or less a not until the 1870's that he published the results one-to-one relationship between the blueprint of this work. In “The Origin of Species” his only and the actual building. Given a building, you reference to humans was right at the end when could probably reconstruct a good blueprint; he said simply ‘Much light will be thrown on the given a blueprint, you could construct the origin of man and his history’. Later he wrote a building. However, we cannot (yet?) do anything book “The Descent of Man” devoted entirely to like this with the DNA sequence of a genome, humans and concluded ‘man, like every other and a recipe is currently a better analogy. A species, was descended from some pre-existing recipe should be sufficient information to make form’. His book included almost everything the end product. However, it is not currently about humans - morphology, emotions, speech possible to infer either what slight differences to and reasoning. However, by this time, other the recipe (DNA sequence) would make, nor to authors such as Lyell had already written books infer the recipe precisely given the finally on the antiquity of humans. As mentioned cooked product. Okay, you might be close each earlier, Darwin had based his scientific approach time, but there is not a simple one-to-one and reasoning on the high scientific standards of relationship. However, in the present context, the Lyell, although Lyell himself at that time sequence, given it is transcribed, processed and (1830s-1840s) was opposed to evolution. Lyell’s translated in a cell with its own information, is book on the antiquity of humans was part of his sufficient for the organism to develop. That is working through Darwin’s reasoning, and the key information in the present context of the coming to accept some of the main evolutionary sufficiency of the processes of microevolution to conclusions. explain macroevolution. Thus the first two major sections (macro and With respect to humans, the dominant view in micro-evolution) are no longer controversial the 19th century was that of the early-mid 17th within science. Evolution has occurred; century French scientist and philosopher Rene
20 Points on the structure and testability of Darwin’s theory 24
Descartes (pronounced ‘day-cart’), whose theory between Charles Darwin and Arthur Russell was of a gulf between humans and all animals. Wallace because Wallace eventually became Descartes concluded there was ‘material’ matter more of a spiritualist and assumed that and ‘mind’ matter. According to Descartes’ view ‘something else’ was required to explain the the human mind was quite different from that of origin of the human mind. any animal. They (and basically everything except the human mind) should be considered as Darwin accepted the work from comparative machines or automata, responding to stimuli in anatomists (such as Thomas Huxley) that chimps the environment. On this (Descartean) view, the and gorillas were the most similar primates to realm of science was the material world (which humans. As mentioned above, he made theologians should leave to scientists); observations on the development of young conversely, the realm of human mind and speech babies (his own) as they gained new abilities. was not the realm of science and should be left His conclusion was that many animals showed, to theologians. Sorry, but the scientists now want in at least a minor way, features more strongly the mind back! developed in humans. Some of his work helped lead to psychological and behavioral studies on This ‘dualist’ view is certainly non-evolutionary animals, though it was not until 100 years later in a Darwinian sense because it hypothesizes an (in the second half of the 20th century that the unbridgeable gap between humans and all other subject really took off. The Descartes view of forms of life. It has already pointed out that animals still has a small following even today, earlier (17th and 18th centuries in particular) the though many recent studies (in the last 20 years Great Chain of Being had been the dominant in particular) have made it almost impossible to view and then it was assumed that there should defend. It has only been in the last 30 years that be a continuous series of animals up to and the close phylogenetic relationship between including humans (and this would have included great apes and humans was established, and even mental attributes). Indeed when the great apes more recently their mental abilities studied (chimpanzees, gorillas and orangutans) were scientifically. first discovered (in the 17th century) their close similarity to humans was considered to support the Great Chain of Being (this is another form of the Principle of Continuity!). It is ironical that this early continuity view (more in agreement with modern thought) was later replaced by Descartes’ view of a great gulf between humans and all animals.
At that time there were political and religious Figure 3. Types of genetic differences between humans and advantages in accepting Descartes' view of chimpanzees. All differences between the species are the humans; it established science as an independent normal types of differences found within populations. discipline not subject to the theologians (who Genetically, humans arise quite ‘naturally’. were a pretty brutal lot who burned people at the Genomics is another other area that is stake that they disagreed with). From the 18th contributing more and more to demonstrating the century onward, Descartes ‘scientific’ distinction sufficiency of known genetic mechanisms. As an of the human mind was accepted almost as example, the complete genomes of humans and a axiomatic, so much so that when Darwin was a chimpanzee are known, and it is natural to ask student at Edinburgh, a student scientific society (Penny 2004) whether there is anything in the struck out from its minutes all reference to talk human genome that could not arise by normal by a member who advocated a ‘materialist’ genetic processes? The differences we see are view, that is, the mind is dependent on material the result of the normal microevolutionary (physical) matter. This attitude to the human processes of genetics (see Figure 3); including mind was probably the only major difference
Biology International Vol. 47 25 Penny point mutations, small insertions and deletions, frequencies between generations; even though duplications of parts of the chromosome, the rate of change between generations may be activation of retrotransposable elements, variable. Changes in gene frequency in a variation in copy number and fusion of two population occur on a biological/ecological time chromosomes to form chromosome 2 in humans. scale, rather than during the life time of an All these are perfectly normal genetic processes, individual cell. The gene frequencies in a there is nothing special about humans as far as population at any point in time can be our genetics or our genome is concerned. There considered the equivalent of the state during a are certainly extremely large numbers of point chemical reaction. Of course we are not limited mutations and small insertions and deletions to just changes in nucleotides. Normal processes between chimps and ourselves, but again the occurring in individuals include small or larger numbers are as expected from measuring natural insertions and deletions, chromosome fission variability in populations. In contrast, wouldn’t and fusion, chromosome gain or loss, increase in it be fascinating if some Kindly Friendly Creator ploidy level (numbers of sets of chromosomes in (the KFC model), or a group of itinerant space a nucleus, and so on. travelers, had inserted into the human genome a whole lot of genes for wisdom and intelligence. Continuity is sometimes called ‘gradualism’, but Just think; genes for wisdom and intelligence this is a highly ambiguous and misunderstood inserted into the human genome. All we would term. Other non-darwinian theories could still have to do is find some way of turning those meet some of the requirements of continuity, for genes on! example, orthogenesis. In this case, orthogenesis doesn’t have a testable mechanism (it just asserts Conclusions, consequences and limitations of an innate tendency towards becoming a more the mechanism complex organism, for example – the long extinct Eohippus will (must?) eventually evolve The Principle of continuity – “Natura non into a horse). We come back to this under facit saltum” component 18, ‘No predetermined pathways of The principle of continuity is basic to scientific development’. thought - nature takes no ‘jumps’, we can’t explain things scientifically by miracles. We Thus it is useful to consider analogies from the can’t say, “suddenly, the ancestral bird had physical sciences under continuity (and feathers” and consider it as a scientific microscopic reversibility), that is, a mechanistic, explanation. Nor can we say, ‘suddenly all the step-by-step approach. Evolution is thus using planets were rotating in ellipses around the sun, the standard scientific approach. We can (but not in the same plane and all in the same direction here) apply the same approach to the origin of and’. Rather, in sciences such as physical life - in the early stages each step will be a chemistry, thermodynamic analyses assume normal chemical one; later it will probably be a continuity between successive microstates of the genetic mutation. chemical system. Change between each successive microstate is changing according to Populations and individual selection. known mechanisms. In principle, each Individual selection arises from the nature of successive microstate is considered reversible. inheritance and from competition, both inter – Thus the concepts of continuity in evolution and and intra-specific. The exact, or even microscopic reversibility in chemistry and approximate, mode of inheritance was a mystery physics are basically similar. in the mid 19th century (except perhaps to Gregor Mendel who published a few years later Reversibility in the sense of physical chemistry in the 1860's). As mentioned above, all that was just requires that a process can be broken down needed initially was the knowledge that there to large numbers of intermediate microscopic was transmission from parents to offspring; this steps, each of which is reversible. In biology, we was the 'known mechanism’ – it could be emphasize the continuity by the overlap of gene observed occurring repeatedly, even if they
20 Points on the structure and testability of Darwin’s theory 26 certainly did not understand the biochemistry in per year – the numbers of each were predictable the 19th century. The effect of selection was within limits. In other words, stochastic events perhaps the major reason leading to the loss of were also subject to predictions – at least ‘on essentialist thinking about species (that required average’. species being held together in some unknown manner). It is hard for us to realize today just Early 19th century (and since Newton at least) how dominant essentialism had been in so many science was very deterministic. Newton's laws aspects of medieval thinking. In an indirect way were considered the model of good science and it remains in philosophies derived from Hegel, appeared to allow the calculation of the positions an early 19th century German philosopher - of the planets hundreds of years into the future, these include fascism and Marxism and some or back into the past, provided the initial other radical philosophies and/or religions which measurements were sufficiently accurate. To advocate supporting your ‘group’ to the many people, an essential part of science was detriment of others. this determinism. In addition, much of theology was also deterministic, extreme forms were This reliance of the mechanism on ‘individual’ ‘predestination’ where the life of an individual selection did not in any way preclude was predetermined or ‘preordained’. There was a cooperation within and between species. The general acceptance that ‘at the appointed time’ concept of what we would now call an individual was ‘called’ by their Maker, ‘coevolution’ had been recognized earlier and chance was not considered a normal part of Lyell, for example, had discussed beneficial events in the world. Indeed, to suggest that interactions between species. However, ‘political something was ‘random’ or ‘chance’ was almost philosophers’ and economists often had no blasphemy, everything had to have a precise knowledge of positive interactions within determined cause. biology and concentrated only on the negative aspects of selection. The handling of ‘chance’ within Darwin's writing was sometimes ambivalent as there was Chance - stochastic processes always the possibility that what appeared to be Allowing chance events to play a major role was ‘chance’ may just be due to as yet unknown perhaps the most original aspect of Darwin's causes. Nevertheless, the recognition that chance theory, and perhaps the most criticized at the occurred in: time - ‘the law of the higgledy-piggledy’ was the the production of variation; view of one physicist-philosopher (John whether it was advantageous (either now or Herschel). It has already been mentioned that in the near future); Darwin’s realization that strong conclusions can whether advantageous variation was present be drawn about chance events if the numbers of when ‘needed’ (say as the climate observations are large, came from the early changed); and Belgian statistician Adolphe Quetelet (ket-el-ay). even if advantageous, whether it would help For example, he had correspondents from a particular individual. southern England to southern Germany, and who All these were features new to science, and the sent changes in weather patterns. Quetelet modern molecular genetics view of neutral combined the results from these correspondents evolution places even more emphasis on and identified major continental-scale patterns in stochastic processes. the weather – such as cyclones and anticyclones, and cold fronts that moved across Europe at An important point to emphasize is that around 50 km/hour. In the present context he possessing an ‘advantageous’ mutation is no showed that when there were reasonable guarantee it will help in an individual case. This numbers of events, that even the numbers of is because there are many other factors affecting ‘irrational’ events per year could be predicted. survival. Consider an example (from Riddiford His examples included the numbers of murders, and Penny, 1984) of two thistles growing on the suicides and misaddressed letters in a country bank of a stream. One gets swept away in a flood
Biology International Vol. 47 27 Penny and leaves no descendants. We certainly cannot There used to be considerable argument over conclude that the remaining plant was ‘better’ whether the mechanism of numerous slight than the other. A selective advantage is averaged modifications being selected over long periods over many individuals; it is not valid to conclude of time, would really work. Nowadays there are that the survivor was ‘better’ than the non- many cases of short-term evolution. We already survivor from single cases. have the examples of human effects on natural populations (Darimont et al. 2009), in vitro RNA Adaptations, new features and the fit between evolution, and genetic algorithms for computer the organism and its environment programs. Another example is that in some In many ways this is a key point in cancers, cells increase their resistance to understanding the consequences of evolutionary chemotherapy over time. There may be a theory. Darwin showed that it was possible, in duplication of a gene that gives a slight principle, for a natural mechanism to explain the resistance against the drug being used for overall ‘fit’ between function, form, and chemotherapy, and so these cells grow slightly environment. Any slightly improved (inherited) faster than the others. Having two copies of the variant that tended to fit the environment better gene increases slightly the chance of another was more likely, on average, to survive. Given duplication of that gene, which gives somewhat time, and repeating the processes over and over more resistance, which means the cell grows again, provided an explanation of the apparent slightly faster - and so on. Another well know design in nature. case are the ‘super-bugs’ that are bacteria resistant to a large number of antibiotics. In This process of ‘adaptation’ has resulted on a lot other cases, bacteria or yeast are grown on a new of arguing over wording. Sometimes people will medium that has a compound (source of energy) say something like, “long teeth are an adaptation that the organism is not able to use. As long as a for carnivores …”. Using “for” in that low level of normal sugar is supplied (which expression raises difficulties. It sounds almost as keeps the organism alive) mutants often arise if there is ‘purpose’ in having the long teeth (or which allow the new compound to be used whatever other feature being considered). Mouth slightly. This can continue, with new mutations parts of insects are adaptations ‘for’ feeding, allowing even better growth. Experimental sunken stomata are adaptations ‘for’ reduced evolution with microorganisms is a very active water loss in desert plants. This usage is really research field. only a problem over the use of words; we are using a shorthand expression for a much longer It would take much longer to do similar statement. We could say something like, “over experiments for organisms with a long life-cycle, millions of years there has been an increased elephants or oak trees. But the principles are tendency for carnivores to survive if they have now established. The mechanism proposed by slightly longer teeth”, etc. Although ‘correct’, it Darwin works in practice. This does not ‘prove’ is rather tedious - like being politically correct it has worked in a particular case, only that it can all the time. You do have to be careful in science work. To most people in the early 19th century, not to get distracted over problems of wording. scientists and others, a mechanism for the Remember the story about the famous increase in morphological complexity over evolutionist John Maynard Smith. On arriving at geological periods of time was beyond natural morning tea one day he found an intense explanation. Even though many could accept discussion going on. ‘Are you arguing about the changes from an existing form they could not world? he asked. ‘If so, I am very interested. Or see how mammals arose from reptiles, for are you arguing about the use of words? In example. All that could be suggested by which case, I am not interested at all’. Words in Darwinians in the 19th century was that given a language have several shades of meaning; we both the continuous development of new just have to be clear in our usage and then get on variation (as seen in artificial selection) and with understanding the world and how it works. many intermediates over long periods of time, that novel features could arise. Because this was
20 Points on the structure and testability of Darwin’s theory 28 somewhat vague, it is not surprising that genetics of development. We say that feathers untestable alternatives (such as orthogenesis) were ‘co-opted’ or ‘recruited’ for flying, from were suggested even by people calling their original function in insulation. Similarly, themselves scientists. None of these alternative we see that with gene duplication, one copy may mechanisms have been successful, and none retain its original reaction, and the other may get depended on 'causes now in operation’. recruited into a new function. (Orthogenesis is just the circular argument that there was some unknown mechanism, or driving Lack of perfection force, that caused animals to follow certain lines Darwin had the outlines of his theory in 1838 of development through time, the same pattern and wrote increasingly large summaries in 1842 of evolution that had already been observed!) and 1844, the last being well over 100 pages (de The development of molecular biology has Beer 1960). However he did not publish the shown an important mechanism of gene (and theory until 1859 and one suggestion (Ospovat even genome) duplication, followed by 1981) for the 20 year delay was that Darwin did specialization of the duplicates, that leads to not see initially how variation would arise that increasing complexity of the genome. would always lead to a perfect fit between the organism and its environment. There did not An example of the type of problem pointed out seem to be a mechanism that would lead to the by critics is given by the evolution of feathers. right variation at the right time. It was only in On the surface, it is difficult to imagine a series the 1850's (according to Ospovat) that Charles of intermediates between feathers and reptilian Darwin realized both that, scales where the intermediates would assist a) variability being generated regardless of flying. Surely, the argument went, feathers the ‘needs’ of the organism could not would be no use for flying until they were fully guarantee that useful variability would formed. And if the intermediates were of no use, be available when needed, but then they could not be acted on by the processes b) organisms (including humans) were not of natural selection. (Unless there was an perfectly adapted to their environments. advantage to the organism, there is no selection.) In other words, there was no mechanism to Some people then suggested ‘macromutations’ guarantee perfection, and indeed organisms where feathers appeared, fully formed, all at (though they did fit the environment pretty well) once. This has been called the ‘hopeful monster’ were indeed not perfectly adapted. theory. However, it is not referring to a ‘mechanism now in operation’ - we did not see Previously it was almost axiomatic that such mutations today, and even is we did the organisms were perfect for their environment; ‘bird’ would not have all the other prerequisites surely no all powerful creator would make (wings, musculature, etc.) needed for flying. The anything less than perfect! This lack of standard explanation is that feathers did not arise perfection then became one of the most powerful ‘for flying’ but for insulation, and that they were tests between Darwin’s new evolutionary model, a useful ’pre-adaptation’ for flying. If early and the earlier creationist biological model feathers increasing insulation (and thereby aided (itself formed by an earlier generation of temperature regulation) then intermediate states scientists, such as John Ray). Many examples between scales and feathers would benefit their could be given but the lack of absolutely perfect possessors. This is at least a reasonable vision in humans is one - birds have better hypothesis, and now the best evidence comes vision, so better vision is possible. Another was from fossils of early ‘feathered dinosaurs’ – that organisms introduced into new countries small theropod dinosaurs that are the ancestors often increased in numbers so fast that they of birds. The most complete evidence for a became pests. The interpretation was that the general mechanism comes from gene duplication indigenous species were less than perfectly and divergence, and maybe a test of the adapted to their environment, allowing the new insulating feather hypothesis will eventually species to increase dramatically. Nowadays we come from an understanding of the molecular are aware that an organism introduced to a new
Biology International Vol. 47 29 Penny environment would not have many of the sunken stomata, fewer stomata, stomata only diseases and pests that might limit its numbers in under the leaves, stomata only open at night, the original home of the species – but why create hairs that reflect light (reducing light the diseases and pests in the first place? There absorption), and so on. The physical and are innumerable examples of lack of perfection, chemical constraints could be solved several we can think of: different ways. development of cancer in animals; calcium loss from bones, particularly in older A common phrase to describe the issue is people; ‘contingency’. The actual organisms we observe rubisco and oxygenase, affinity of the are ‘contingent’ on many events in the past; nor enzyme for both CO2 and O2 limits the can we predict the precise order of events off rate of photosynthesis; into the future. We can often predict specific lack of cellulase in most herbivores; events, such as a mutation that might give lack of nitrogenase in eukaryotes; resistance to herbicides, even if we cannot astigmatism and sight, many animals have predict whether the mutation will arise. This better vision than humans; overall conclusion helps distinguish Darwinism need for vitamins, including essential amino from orthogenesis that assumed predetermined acids, and vitamin C in humans and pathways of development. Figure 4 shows three guinea pig (intelligent design would main ideas at the time the Origin was published, surely produce all these compounds namely catastrophism, orthogenesis, and the within the organism?) Hutton/Lyell/Darwin view of using mechanisms Indeed the lack of perfection is the rationale of [actualism]. The three main views are genetic engineering, for example, resistance of distinguished as to whether they are relying on plants to insect herbivores. It is now almost known (knowable) mechanisms, and whether axiomatic that we can ‘improve’ on some they require continuity of process between all aspects of nature; this attitude was certainly not forms of life. However, an important reason for true in the early 19th century when it was introducing this here is because it is very axiomatic that organisms fitted their important to NOT get forced into artificial environment perfectly. binary choices. Figure 4 shows that forcing an artificial binary choice between catastrophism No predetermined pathways of development and ‘uniformitarianism’, when there were at As mentioned earlier, the two main approaches least three main choices, can seriously mislead. before Lyell and Darwin were catastrophism and We return to this point at the end because people orthogenesis/uniformitarianism. Orthogenesis in even today we can still be misled by artificial particular suggests that organisms, over long binary choices about evolution. periods of time, slowly unfold over predetermined pathways. If, for example, all vertebrates were removed from the earth, then (under orthogenesis) they could develop again. In contrast, under actualism (Darwinism), there is no expectation that the same body plans would evolve again – but the same chemical and physical principles would apply. The conclusion (no preformed pathways of development) reinforces the earlier one about no ultimate causes. Simple physical principles will limit the Figure 4. Three approaches to studying past events from the types of organisms that evolve, but there are 1830-40s, the time when Charles Darwin developed his ideas many body plans that fit physical necessities. based on the Lyell and Hutton approach to understanding past geological events. Some authors had formed the artificial For example, a plant adapting to drier more binary choice between catastrophism and ‘uniformitarianism dessert like conditions will have to reduce water - which could included both orthogenesis and some forms of loss, but this could happen in several ways – actualism (Darwinism). This missed the distinction that
20 Points on the structure and testability of Darwin’s theory 30 neither catastrophism nor orthogenesis could propose any A useful fall back position for theistic thinkers is testable mechanism for studying past events, whereas Hutton, Lyell and Darwin aimed at just that. In general, it is very to modify the above extract to ‘responsibility’ important to avoid forced artificial binary choices. and ‘care’ for nature; this is a big improvement over the traditional view, and one that we all No need to postulate an ‘ultimate’ cause, etc. applaud. However, the traditional view was that The lack of the need to postulate a purpose nature was created for the benefit of humans; it behind biological (and physical) processes was a was all part of the purpose of the universe. major implication of the theory, and probably Modern science has changed that view why evolution had so much impact in both completely; humans are responsible for the science and the general community. Previously, consequences of our actions. one of the strongest themes in biology had been teleology - organisms were designed ‘for a Humans are ‘a part of’ nature – not ‘apart purpose’. This united science and theology under from’ nature ‘natural theology’. If the origin of complex We are a part of nature, not apart from nature. organisms, and the adaptation of organisms and Nature was not created for humans, nor are we their environment, could be explained exempt for the laws of nature. This is one of the scientifically (by ‘known’ processes still most far-reaching conclusions from evolutionary occurring today) then it was not necessary to theory. It was one of the most widely believed postulate a purpose (teleology). It is now aspects of indigenous knowledge throughout the standard biology to exclude teleology and we world that plants and animals were created by tend to forget that this was a major achievement some (KFC) deity ‘for them’. of 19th century biology. The extreme form was to assume that the world was created ‘for’ For many people, a difficulty with a full humans, and animals and plants created for evolutionary theory is that it did not appear to human benefit. A classic example is - explain, or at least demonstrate a need for, ‘and God said unto them, Be fruitful and ethical and moral systems that characterize multiply, and replenish the earth, and subdue human (and many animal) societies. Quite a few it: and have dominion over the fish of the sea, scientists accepted evolutionary ideas, but still and over the fowl of the air, and over every sought a non-evolutionary explanation of human living thing that moveth upon the earth. And ethical, moral and religious systems. This is one God said, Behold I have given you every herb of the active areas of current research with bearing seed, which is upon the face of the studies on higher primates (especially apes), earth, and every tree, in which is the fruit of human development, and computer simulation. the tree yielding seed; and you it shall be for The origin of language is now seen as firmly meat. And to every beast of the earth...’ embedded within the great apes, but what about Genesis 1: 28-30 religion. Is there an advantage to individuals if they are members of a group with firm shared ‘Subdue’ it, ‘have dominion over’, ‘I have given beliefs? How is it that religion seems to you every herb …’ are very strong statements to encourage killing members of ‘other’ groups? Is the effect that the world was created for the this the same basic phenomenon that we see in benefit of humans. These attitudes were some chimpanzee societies where they are challenged by Darwin's theory and could no tolerant and supportive to others within their longer be substantiated scientifically. We now own group, but willing to kill (male) chimps consider humans as ‘a part of nature’, not ‘apart from other groups? Is there an evolutionary from nature’. The rise of the modern advantage to individuals that share strong conservation ethic is based on this major change beliefs? It cannot be the specific beliefs that of attitude that humans are subject to the laws of inherited, just the ability to have strong beliefs? nature, not that nature existed for the benefit of In addition to the positive side of religion, there humans. Nature was not created ‘for human is there a ‘Dark Side’? benefit’, and we continue this theme next.
Biology International Vol. 47 31 Penny
There is a wide spectrum of view on the physiology, development, ecology and behavior sufficiency (or otherwise) of microevolutionary and we would be very surprised indeed not to processes. The official Catholic view is that expect similar gains this century. As just one everything occurs according to ‘natural law’, example, we still do not know all the except for two interventions – one in the origin mechanisms required for the origin of life (yet of life, the other in the origin of humans. This is probably most scientists think that such very close to the full Darwinian position. mechanisms exist). Despite this official view, individual Catholics are probably as diverse in their views as anyone There are perhaps a few areas where some else! However, where you feel comfortable on researchers are suggesting radically different the spectrum is your personal business, not ours! mechanisms of evolution in the past from those We will come back to this at the end and occurring today. A classic example is perhaps illustrate some of the possibilities in Figure 5. the suggestion of an ‘explosive’ radiation of modern orders of mammals and birds after the ‘sudden and unexpected’ extinction of dinosaurs by the asteroid that hit the earth at the end of the Cretaceous (65 million years ago). An asteroid hitting the earth is well established, and although we cannot (and do not wish to!) observe such a large impact in the present, there are observable effects of the impact (such as the layer enriched in the element Iridium) all over the earth, including several parts of Europe to the South Island of New Zealand. The extinction of Figure 5. A range of possible views to evolution. It starts dinosaurs as a result of the impact is more with traditional indigenous knowledge of continued spontaneous generation, and then moves to the classical problematic, there is not yet a single piece of creationist view of John Ray from 1691. Some authors have evidence that their demise was either sudden and argued that human language has no counterpart in animals, so unexpected, nor simultaneous with the asteroid this is a major discontinuity. Some authors (including Marxists) have thought we were missing some important impact. feature. The liberal version of Intelligent Design is next (though more conservative views would be closer to classical However, one concern from a mechanistic view creationism). The official Catholic position has two interventions of a Creator. Finally, there is the mainstream is that we do not know of any developmental or evolutionary view that natural laws, with time, is sufficient. genetic mechanisms that would allow such a Other orderings of the viewpoints are certainly possible. With the possible exception of the 100% natural law (the standard rapid appearance of major developmental, Darwinian view) all have been considered consistent with a physiological and behavioral features of orders range of religious or non-religious views. The key point is of modern mammals and birds within a few that there have been a wide spectrum of views in the past, and that we should never allow ourselves to be trapped by million years. Why would the right mutations artificial binary choices such as ‘evolution versus creation’, arise just when they are required? Modern work or ‘evolution versus intelligent design’. The real world is far more interesting than that. is much more cautious, and considers that the modern orders of both mammals and birds were Not all mechanisms are known. developing from at least 100 million years ago This is really self-evident, but it is important to (Ma), and this allows ample time for the types of state it for several reasons. From a logic mutations that we know about to occur. Perhaps viewpoint it is necessary to distinguish between we need to know much more about the modes of using only mechanisms that can be studied in the competition between the early mammals and present, from the presumption that we know all birds, and the smaller pterosaurs and dinosaurs. the mechanisms – a very different issue. We have seen a huge increase in knowledge during Discussion the 20th century, which continues today. There Science as an exciting process, and it is are major gains in molecular biology, genetics, important to emphasize that ideas evolve with time. It is not sufficient just to learn science as
20 Points on the structure and testability of Darwin’s theory 32 we understand it now, science is dynamic, and Give the range of possibilities in Figure 5, then science is exciting as it develops. It is essential state that, to have the basic scientific concepts of your I am comfortable at the 100% natural law end subject area, but it is also important to know of the spectrum how to keep learning, to welcome new ideas and Each person should place themselves where to test them. Often ‘new’ ideas turn out to be old thy are comfortable, ideas, maybe in a slightly different guise. I will never ask them where they are Welcome them as stimuli for new analyses or comfortable, but experiments, but be prepared to be critical. Be Nevertheless, I require a fully scientific prepared to discard ideas that are now answer to a scientific question. (As an superseded. The important points here are the analogy, if I ask a student the formula of interaction of macroevolution, microevolution, water, I want the chemistry answer, not and the question of sufficiency (or otherwise) of that “water is ‘organic’, and has great microevolution to explain macroevolution. Each cleansing and healing powers”! H2O is of these main three topics is made up of what I want.) individual processes, each of which can be tested. Although the overall structure of the Breaking up the theory into 20 points in this way theory appears complex, each component is is useful for several reasons. Firstly, an relatively straightforward evaluation of each of them is possible – they could each be tested separately. Indeed, all have Although Darwin’s ‘theory of descent’ been to varying degrees. We know, from RNA (macroevolution was accepted by biologists viruses, that the processes do lead to evolution within about 10 years of the Origin, it took much over the short term. There is just no question for longer for the importance of his most of the points. But another area of use is for microevolutionary principles to be recognized. It challenging those who cast doubts on evolution. took a synthesis of genetics and population Which of the 20 points listed above do they biology in the in the 1940's and 1950's before disagree with, or are they rejecting all 20 of that happened – and perhaps it then required them? When listening to some arguments it has other authors to explained the synthesis to other been impossible to tell exactly what the authors biologists (that is, they left out the mathematics). are criticizing, I hope that the 20 points helps Of these Julian Huxley's ‘Evolution: the new each reader evaluate evolution. synthesis’ (1942) is perhaps the best overview of neo-Darwinism and should always be consulted References by anyone interested in classical neo-Darwinism. Appel, T.A. (1987). The Cuvier-Geoffroy The book edited by Mayr and Provine (1980) Debate: French biology in the decades has many articles covering the development of before Darwin. Oxford University Press: the synthesis but the details are outside our Oxford. scope. Barrett, P.H. (1977). The collected papers of However the study of evolution, like any area of Charles Darwin. Chicago University Press: science, has continued to develop with perhaps Chicago. the main gains being in the area of evolutionary ecology and behavior, molecular evolution, and Bowler, P.J. (1984). Evolution: The history of an computing and mathematical precision. There is idea. Univ. Calif. Press: Berkeley, Calif. an increasing acceptance that the processes of microevolution are sufficient for Burkhardt, R.W. Jr. (1977). The Spirit of System: macroevolution. If we can get to a human Lamarck and evolutionary Biology. Harvard genome from an ape like genome of the Univ. Press: Cambridge, Mass. human/chimpanzee/gorilla ancestor, then that is a powerful conclusion.
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Cuvier, G. (1817). Essay on the Theory of the Lewontin, R.C. (1974). The Genetic basis of Earth (reprint, 3rd Ed. 1978, Arno Press, evolutionary change. Columbia University New York) Press: New York.
Darimont, C.T., S.M. Carlson, M.T. Kinnison, et Lyell, C. (1830-33). Principles of Geology al. (2009). “Human predators outpace other (reprinted 1990, Chicago University Press, agents of trait change in the wild.” Proc. Chicago). Natl Acad. Sci. USA. 106: 952-954. Mayr, E. (1982). The Growth of Biological Darwin, C.R. (1969). The Autobiography of Thought: Diversity, evolution and Charles Darwin. (N. Barlow, ed), New inheritance. Harvard University Press: York: Norton. Cambridge, Mass.
Dean, D.R. (1992). James Hutton and the history Mayr, E. (1985). “Darwin's five theories”, in The of geology. Cornell University Press: Ithaca, Darwinian Heritage (D. Kohn, Ed.) NY. Princeton University Press, pp 755-772.
De Beer, G. (Ed.) (1960). Darwin's Notebooks Mayr, E. (1991). One long argument: Charles on the Transmutation of Species. Brit. Mus. Darwin and the genesis of modern (Nat. Hist.) Hist. Ser. 2 (2): 27-73. evolutionary thought. Harvard University Press: Cambridge, Mass. Farley, J. (1977). The spontaneous generation controversy from Descartes to Oparin. The Mayr, E. and W. Provine (Eds.). (1980). The Johns Hopkins University Press: Baltimore, Evolutionary Synthesis: Perspectives in the MD. unification of biology.
Greene, John C. (1959). The Death of Adam: Moorehead, A. (1969). Darwin and the Beagle. evolution and its impact on Western Penguin Books: New York. thought. Iowa State University Press: Ames, Iowa. Murray, Martyn. (2003). “Overkill and sustainable use.” Science 299: 1851-1853. Herbert, S. (2005). Charles Darwin, geologist. Cornell University Press: Ithaca. Oparin, A. (1938). Origin of Life. Second edition 1953, Dover Publications. (particularly Holdaway, R.N. and Jacomb, C. (2000). “Rapid pages 1-15) extinction of the moas (Aves: Dinornithiformes): Model, test, and Ospovat, D. (1981). The development of implications.” Science 287: 2250-2254. Darwin's theory: natural history, natural theology, and natural selection. 1838-1859 Hull, D.L., P.D. Tessner, and A.M. Diamond. (1978). Planck’s principle. Science 202: Paré, A. (1585). Monsters and Marvels. 717-723. (translated and introduced, Palliser, J.L. 1982) Huxley, J. (1942). Evolution: the modern synthesis. Penny, D. (2009). “Charles Darwin as a theoretical biologist in the mechanistic Jacob, F. (1973). The Logic of Life: A history of tradition.” Trends in Evolutionary Biology heredity. Pantheon: New York. 1: e1.
Penny, D. (2004). “Our relative genetics.” Nature. 427: 208-209.
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Penny, D., M.D. Hendy and A.M. Poole. (2003). “Testing fundamental evolutionary hypotheses.” Journal of Theoretical David Penny is founder Biology 233: 377-385. and past Research Director of the Allan Popper, K.R. (1972). The logic of scientific Wilson Centre with discovery. Hutchinson: London. interests in evolutionary trees, the mechanisms of Raven, C.E. (1986). John Ray: naturalist. evolution, testing Cambridge University Press, Cambridge. hypotheses about evolution, the peopling of the South Pacific, and the history of Riddiford, A. and D. Penny. (1984). “The evolutionary thought. He is a rampant scientific status of evolutionary theory.” Popperian who enjoys finding tests of Pages 1-38 in J.W. Pollard (Ed.) hypotheses about evolution – under no Evolutionary theory: paths into the future. circumstances should you ‘believe’ a John Wiley and Sons: London. hypothesis, seems to be his motto. He teaches and supervises postgraduate students Sandler, I. and L. Sandler. (1985). “A conceptual at Massey University. He is a Fellow of the ambiguity that contributed to the neglect of New Zealand Royal Society, and this year is Mendel’s paper.” Hist. Phil. Life Sci. 7: 3- president of the US-based Society of 70. Systematic Biologists. His main hobby is his research. Stevens, P.F. (1994). The development of biological systematics: Antoine-Laurent de http://awcmee.massey.ac.nz/people/dpenny/i Jussieu, nature, and the natural system. ndex.htm Columbia University Press: New York, NY.
Tyson (1699). Orang-outang, sive Homo sylvestris: or, The Anatomy of a Pygmie Compared with that of a Monkey, an Ape and a Man. London: The Royal Society. (reprinted 1966, Dawsons of Pall Mall: London)
Biology International Vol. 47 35 Penny
Lessons from Darwin’s laboratory
Peter Lockhart, Claudia Voelckel
Institution Institute for Molecular BioSciences, Allan Wilson Centre, Palmerston North, New Zealand
“The overarching aim of conservation most genetically distinct taxa are preserved? biology is to protect biological diversity and (Hartman and Steel, 2006; Pardi and the processes that sustain it in the face of Goldman 2007). perturbations caused by human activity” (Moritz, 2002). A different and important criterion in conservation biology concerns prioritizing This requires that nature reserves preserve habitats, species and populations so that the not only genetic diversity but also the adaptive potential or so called persistence of adaptive potential of biodiversity. The biodiversity is maximized. The aim here is former is well understood and relatively to act in such a way that the processes that easy to measure, at least for parts of sustain present and future biodiversity can genomes that do not appear to vary in be protected (Cowling and Pressey, 2001). response to environmental selection. But what are these processes? Until recently, Measurements are typically made through there had been relatively little progress in comparison of gene sequences, DNA answering this question. However, fingerprint profiles and/or analyses of technological and methodological advances, microsatellite loci. as well as a rethink of ideas on the nature of When gene sequences are compared species (Mallet, 2008) may soon see investigated, evolutionary history is often significant progress in our understanding. inferred and used to inform about One stumbling block in particular has been phylogenetic diversity, i.e. measure of the identification and understanding of the evolutionary relationship between and extent adaptations important for explaining species of divergence between organisms (Faith, interactions and phenotype/environment 1992; Faith 2007). Such analyses can be associations. Studying adaptation is not framed with respect to landscape geography trivial and comprises fitness studies as well and used to identify geographic regions that as studies of the genetic basis of adaptation. are potential hotspots (historical refugia) or Several approaches have traditionally been melting points (places of migration for employed to discover genes underlying species). Measures of phylogenetic diversity adaptations, most notably studies of are potentially very valuable in conservation quantitative trait loci (QTL; Symonds et al. biology as they provide an objective criteria 2005) and comparative gene expression for decision making, such as in the Noah’s studies in common garden and reciprocal Ark problem. i.e. given a limited budget, transplant settings (Mitchell-Olds and and cost associated with conserving Schmitt, 2006). However, QTL studies are different species, which are the species and really only amenable to readily crossable, habitats (geographic regions) that we should relatively short-lived species. Similarly, put most effort into preserving so that the common garden and reciprocal transplant
Lessons from Darwin’s Laboratory 36
studies are practical only for a few easily responses to environmental change cultivated species with rather short life (Hoffman and Daborn, 20006; Hoffman and cycles. Most species that need protection or Willi 2008). The technology also provides a which might be good models to evaluate the means to obtain genome wide nuclear ‘persistence’ potential are either not easily markers that can be used to investigate cultivated, longer-lived, or have special genotype/environment associations habitat requirements, making them (Nordborg and Weigel, 2008) and better impractical to reciprocally transplant. QTL assess the evolutionary relationships studies and studies of differential expression between species (e.g Edwards et al. 2007), also require molecular resources that until the complexity of their genomes and the recently have only been available for a few extent of occurrence of hybridization model species. (Holland et al. 2009; Joly et al. 2009).
However, with the advent of high Although hybridization has been much throughput sequencing technologies, not maligned under the biological species only are molecular markers and tools for concept, there has been a great resurgence of gene expression profiling becoming interest by researchers in the phenomenon of available for the above experimental hybridization, in both the extent and approaches, these technologies are heralding evolutionary significance of hybrid in a new age of scientific investigation that speciation and introgression between species can begin to explore genotype-phenotype (Arnold, 2004; Mallet, 2008; Rieseberg, associations and gene expression studies in 2009). Hybrids have traditionally had an native populations of non-model species ambiguous status in conservation (e.g. Weigel and Nordman 2008). (Allendorf, 2004), however it has also been argued that hybridization may provide the With technologies such as 454 and Solexa most efficient means that an organism may sequencing, the sequences of expressed have to respond to rapid environmental genes (EST libraries) can be determined change (Anderson and Stebbins, 1954; very quickly for any organism. These Arnold et al. 2004; Rieseberg 2009). With libraries can then serve as a source for the the arsenal of genome wide markers now development of molecular markers to becoming available through high throughput facilitate candidate gene studies. High sequencing methods, new analytical throughput gene expression studies, until techniques to evaluate the occurrence of recently realized predominantly through hybrids, and automated protocols to infer the microarrays, can also use this technology to ontologies of organisms based on counts of sequence and count mRNA sequences their mRNA transcripts, a means to evaluate directly through tools such as mRNA-Seq the persistence of species, and the and DGE. Other advantages may also render sufficiency of nature reserves to protect sequencing-based gene expression them may soon be realizable. approaches preferable to microarrays especially for within- and between species References studies. For example, if coupled with Allendorf, F.W., R.F. Leary, P. Spruell, and automated ontology analyses (Huang et al. J.K. Wenburg. (2001). “The 2008), studies of differential expression problems with hybrids: Setting provide a potential means to predict whether conservation guidelines.” Trends or not biological processes differ within and Ecol. Evol. 16: 613-622. between species across heterogenous landscapes and environmental gradients. Anderson, E. and G.L. Stebbins. (1954). Such inferences may be used to identify “Hybridization as an evolutionary potential adaptations, and candidate gene stimulus.” Evolution 8: 378-388. sets that contribute to genetic adaptive
Biology International Vol. 47 37 Lockhart & Voelckel
Arnold, M.L. (2004). “Transfer and origin of hybridization and incomplete adaptations through natural Lineage Sorting.” The American hybridisation: Were Anderson and Naturalist (in press). Stebbins right?” The Plant Cell 16: 562-570. Mallet, J. (2008). “Hybridization, ecological Cowling, R.M. and R.L. Pressey. (2001). races, and the nature of species: “Rapid Plant diversification: empirical evidence for the ease of Planning for an evolutionary speciation.” Philosophical future.” Proc. Natl. Acad. Sci. USA Transactions of the Royal Society B- 98: 5452-5457. Biological Sciences. 363: 2971– 2986. Edwards, S.V., L. Liu and D.K. Pearl. (2007). “High-resolution species Moritz, C. (2002). “Strategies to protect trees without concatenation.” Proc. biological diversity and the Natl. Acad. Sci. 104: 5936–5941. evolutionary processes that sustain it.” Syst. Biol. 51: 238-254. Faith, D.P. (1992). “Conservation evaluation and phylogenetic diversity.” Biol. Mitchell-Olds, T. and J. Schmitt. (2006). Conserv. 61: 1-10. “Genetic mechanisms and evolutionary significance of natural Faith, DP. (2007). “Phylogeny and variation in Arabidopsis.” Nature Conservation.” Syst Biol. 56: 690 - 441: 947-952. 694. Pardi, F. and N. Goldman. (2007). Hoffman, A.A. and P.J. Daborn. (2006). “Resource-Aware Taxon Selection “Towards genetic markers in animal for Maximizing Phylogenetic populations as biomonitors for Diversity.” Syst Biol. June 1, 2007; human-induced environmental 56(3): 431-444. change.” Ecology Letters 10: 63-76. Nordborg, M., D. Weigel. (2008). “Next- Hoffman, A.A. and Y. Willi. (2008). generation genetics in plants.” “Detecting genetic response to Nature 456: 720-723. environmental change.” Nature Reviews Genetics 9: 421-432. Rieseberg, L.H. (2009). “Evolution: replacing genes and traits through Holland, B.R., S. Benthin, P.J. Lockhart, et hybridization.” Current Biology 19: al. (2008). “Using supernetworks to R119-R122. distinguish hybridization from lineage-sorting.” BMC Evolutionary Symonds, V.V., V. Godoy, T. Alconanda, et Biology 8: 202. al. (2005). “Mapping quantitative trait loci in multiple populations of Huang, D.W., B.T. Sherman, and A. Arabidopsis thaliana identifies Lempicki. (2008). “Bioinformatics natural allelic variation for trichome enrichment tools: paths towards the density.” Genetics. 169: 1649-1658. comprehensive functional analysis of large gene lists.” Nucleic Acids Research 37: 1-13.
Joly, S., P.A. McLenachan, and P.J. Lockhart. (2009). “A Statistical Approach for Distinguishing
Lessons from Darwin’s Laboratory 38
Claudia Voelckel is a Pete Lockhart is a Feodor Lynen principal investigator of (Alexander von the Allan Wilson Humboldt) Research Centre with interests in Fellow based at the phylogenetic Allan Wilson Centre in methodology, plant New Zealand. Her Phd evolution and pacific work at the Max Planck biodiversity. He is a Institute for Chemical coordinator for the New Zealand Plant Ecology was based on the potato chip - a Species Radiation Network microarray platform that she used to http://awcmee.massey.ac.nz/NZPRN, and investigate the herbivory responses of currently teaches undergraduate classes in tobacco plants when fed upon by insects. plant diversity and biochemistry at Massey After completing these studies for which she University. There, and also at the University received the Beutenberg Society Campus of the South Pacific in Fiji, he supervises Prize for best Phd thesis (2004), she moved postgraduate students. He is a Fellow of the to the University of California (Santa New Zealand Royal Society. Peter likes Barbara) to study gene expression and the Celtic music, plays the banjo badly and adaptive radiation of granny's bonnet occasionally works back stage for local (Aquilegia). In 2006 she joined a Marsden theatre productions. funded research team (Massey University, HortResearch and Landcare) to study the http://awcmee.massey.ac.nz/people/plockhar adaptive radiation of a New Zealand alpine t/index.htm cress. Based at Massey University, Claudia is utilizing microarray analyses and next generation sequencing technologies in her studies. She has recently completed an educational module to help teach students
the principles of microarray analyses.
Biology International Vol. 47 39 Lockhart & Voelckel
Teaching and communicating Evolution : Proposals for innovative approach es and didactic researches
André Giordan
Université de Genève, LDES Uni Pignon - 40 bd du Pont d'Arve CH-1211 Genève, email: [email protected]
Since Darwin and Wallace published their conclusions, the idea of evolution of life is the basis of biological studies. Developments in genetics and molecular biology have brought forth material evidence of evolutionary phenomena, constantly deepening and consolidating explanatory models. However, evaluations of public knowledge of the subject, including samples of high school graduates with scientific diplomas, have revealed great confusion and broad lack of knowledge. These difficulties are not solely linked to external factors such as religion and ideas related to creationism and “intelligent design”. A number of these problems also originate in the functioning of the scientific community itself. There are still dysfunctions in education, including at the university level, and in communication of these ideas by museums and the media. Researchers writing articles in scientific reviews and organizing exhibits in reputed museums unknowingly include in their presentations traces of finalism and concepts such as Homo sapiens being at the summit of a pyramid of beings! It would seem that the scientific models of evolution have not been fully assimilated.
Introduction Furthermore, mentally integrating the idea In teaching programs, including university- of evolution is no simple matter, for it level, evolutionary knowledge is presented requires going beyond the obvious. diversely as an intangible fact, an array of Teaching evolution is fraught with pitfalls. phenomena to be explained, a structuring Unfortunately, secondary and university paradigm etc. The links between traditional textbooks and the usual frontal or genetics, population genetics, genomics, constructivist approaches are not up to the paleontology and molecular biology are not task of broadly sharing this knowledge. The clearly established. Evolutionary arguments answer lies in proposing diverse didactical either remain very implicit, or underlying, or research in biology that can produce tools are taught at the end of a program as a and resources to train teachers, “crowning achievement”! Divergences and communicators and researchers. disagreements between rival scientific schools of thought regarding explanatory Several didactic researches on teaching the methods help maintain pseudo-scientific evolution theory have been carried out. At vagueness. Historical and epistemological first they dealt with the “roadblocks” approaches – in which researchers are ill encountered by the students (Hallden, 1988; prepared – should be more widely Bishop & Anderson, 1990; Fortin, 1990; introduced in curricula, so as to analyze Galanguau-Quérat, 1990; Bizzo, 1994; distorted reasoning processes and more or Trowbridge & Wandersee, 1994; Settlage, less clearly defined opposing concepts. 1994; Ferrari & Chi, 1998; Thomas, 2000;
Teaching and communicating Evolution 40
Crawford et al. 2005). For example, Fortin Firstly, this paper tries to describe the (1994) observed four conceptual types in the situation: where knowledge stands within student population: “evolutionary”, the public at large, and what impact the “transmutationist”, “non-evolutionary” and usual instructions given at the secondary “anti-evolutionary”; Geraedts and Boersma education level may have. Secondly, this (2006) noticed Lamarckian representations. information has been exposed in the context These difficulties are also linked to the lack of the usual presentations within the of understanding of other concepts, such as curriculum (particularly secondary and “genes” (Hallden, 1988), "species" (Van university), school books, web sites and Praet, 1989) or even “time” (Fortin, 1990). museums. Lastly, it is important to find out Others seem more related to difficulties in how the scientific society (researchers, the methodology (Aroua et al., 2001, Dagher teachers and curators...) handle these & Boujaoude, 2005). The other studies are questions in their debates, publications and analysis of curriculum or manuals’ content. communications? Neither the biological Thus, many National programs dodge this facts nor the school material taught are domain or lack evolutionary perspectives neutral: they have an effect on the (Lacombe 1987). The work done in the presentations of knowledge and they school manuals demonstrates a superficial structure the acquisition of a culture. The treatment of the key ideas of life’s evolution questions brought into play here are in general (Jiménez Aleixandre, 1994; questions regarding the status of Life and Jeffery, 1994), regarding the “bushy” Man within society; where he stands and evolution in particular (Quessade et al., what his responsibilities are to the planet. 2007) or reveal the existence of presuppositions (Mathy, 1997). Corpus This corpus is a compilation of preliminary Some pedagogic proposals have also been studies. It was written-up between 1994 and presented to try to rectify this. Zuzovsky 2008 and includes various investigations: (1994), Passmore and Stewart (2002) - the status of knowledge within the highlight the students’ implication in an public at large, investigative paper and Duven and Solomon - evaluation of the acquired (1994) introduce role playing games. Jensen knowledge resulting from the and Finley (1995), Demastes et al. (1995), secondary education’s scientific Ingram and Nelson (2006) introduce the component “conceptual change” framework. Smith - secondary education courses and (1994), Cobern (1994), Rudolph and Stewart books analysis, (1998) introduce an historical or - major National Science Museums epistemological approach; so do Gagliardi presentations or websites analysis, and Giordan (1987), Scharmann (1992) in - analysis of articles found in major the training of teachers. Sandoval and scientific magazines. Morrison (2003) mix investigations and epistemological reflection. In short, most of 1. The level of knowledge about the studies deal with the roadblocks linked evolution within the public at large. to the cultural, socio-cultural or During two museologic projects, multicultural factors, in particular, when interviews of the public at large pertaining to a religious commitment; the were conducted (101, various following studies are noted as some of the European publics) using a most thorough: Lawson & Worsnop, 1992; framework of questions. The data Jackson et al., 1995; Aroua et al., 2001 and was analyzed on a qualitative grid 2002). However, we will not develop this with an itemized list. aspect here… 2. Acquired knowledge evaluation at the secondary education level. This
Biology International Vol. 47 41 Giordan
evaluation was carried out with persons questioned accept the concept of questionnaires (300) along with evolution of human beings from more semi-direct interviews (30) with primitive species². People have come to students who had successfully terms with transformism as far as living received a secondary education beings, a sort of « metamorphosis » where which contained a high scientific every thing perpetually transforms itself in component (Geneva, Paris VII, “everything”. What is most amazing is the Versailles Saint Quentin, Bangkok lack of awareness the students having University students). A similar successfully finished their secondary analytical method to the one used in education in science have about the the first point was considered. evolutionary mechanisms. 42% of them only 3. Books and websites analysis. A mention the «natural selection», 16% talk corpus of documents coming from about the genetic modifications. The other comprehensive sites, course material mechanisms mentioned are the “climatic and books used for secondary changes” (15%), the “glacial period” (12%), education and entry level university the environment « the pressures imposed by education was set-up (French, other species » or photosynthesis. Only 2% English and Hispanic documents). consider the possibility of having The study dealt with the content “mutation” and “natural selection” (texts and icons) and readability simultaneously. The links between the (questions, vocabulary, natural selection and adaptation are not very metaphors...). straightforward. 4. Major National Science Museum presentations analysis. This corpus As far as 40% of them are concerned, “Man incorporated 5 major National is a descendant of the monkey”, 35% talk Museums (New-York, Paris, about a succession “fish – reptiles – first Luxemburg, Geneva, Shanghai...) Man”. 12 % introduce the notion of 5. Analysis of articles found in major “primitive medley” or “primitive species”. scientific magazines. This corpus 88 % of them tend to over-estimate or was made-up of articles found in under-estimate the dates for the apparition or Science Magazine1, Nature, La extinction of the main species... For 21% of Recherche. them, the apparition of Life on Earth is linked to the “Big Bang”! Man’s ancestors Results are frequently mentioned; these students are On the basis of all the questions generated none the less unable to point out their when people are asked about the origin of succession or characteristics. Life or Man, one can see that Evolution is a popular domain of knowledge. 82 % of the In the course materials, on the websites or in the museums, the evolution theory is mainly
1 presented in a formal manner: its As of the 22/12/2008, more than 34 000 references in enunciation is usually based on a set of Science contain the word « evolution » in the title. In Nature, 104995 articles contain that term. observations. Most of the time, it is an ² 5% are undecided, 13% do not adhere to it. “exhibition”, it is rarely an interrogation or a ³ In the education curriculum, even at the university demonstration; more often than not it level, the information is presented differently postulates evolution rather than depending on the case, sometimes as an intangible fact, sometimes as set of yet to explain phenomena , demonstrates it². Moreover, the teacher or sometimes as structural paradigm, etc.. The links the curator gives answers to questions the between classical genetics, population genetics, students or the public don’t ponder; which genomics, paleontology or molecular biology are not really doesn’t make it easier to understand. well established. More often than not the proposed arguments remain very implicit or subjacent or are taught at the end of the curriculum as a “teaser”. Teaching and communicating Evolution 42
Lastly, in the university course material or in concepts...) are also essential in a systemic the prestigious museums it is easy to find approach. Furthermore, each level of this adhesion to the old knowledge (through the transformed knowledge must be challenged, notion of “progress”, supremacy of the reformulated, rallied around and its meaning Homo sapiens, and references to linear forever explained. classification), in particular through their use of words and illustrations. One also finds a Meta-cognitive and infra-cognitive moments lot of tacit knowledge, biased reasoning or must be introduced. As far meta-cognitive the use of more or less defined or opposing moments; two supplementary approaches concepts. may be considered: on the one hand, initiate some questioning about the factual data Discussion (how did they come about? what are their In order to remove some of the scientism, if reasons to be? within what context?): on the not dogmatism from the teaching and other hand, a debate about what is a communication of the evolution theory, to reasonable and critical argument must be make it more efficient, a set of points must initiated. As far as the infra-cognitive be considered … Two especially significant dimension; it is important – maybe through ones will be examined here: role playing games - to bring to the table the 1. The choice of pedagogic and prejudices, beliefs, evidences or to uncover communication strategies. personal convictions. All in all, 2. The relationship of the concepts to opportunities to make a person doubt his epistemology and history within the beliefs must be put forward in order to open scientific community. up a new field of knowledge within a rational perspective. 3.1. The choice of pedagogic and communication strategies. With such 3.2 The relationship to epistemology and complex course content, the head-on history of the concepts. The conflict of pedagogy needs to be re-assessed seriously. opinions and the quarrels between the As well, the constructivist strategies, various scientists’ “cliques” about the including the conceptual change appear too explanatory mechanisms have brought limited to give rise to such a change in understanding of the issue to a standstill knowledge. The students and the public at while promoting a skilful blur. Historical large can learn “against” but also “with” and epistemological approaches – for which those conceptions relating to the history of the researchers and teachers have little the living. Some allosteric environments training – must be introduced on a larger (Giordan 1996, Giordan 1998) thus need to scale. For example, the “adaptation” theory be put in place. In order to have some needs to be debated; otherwise it leads to opportunities to change the learners’ thought erroneous conclusions such as that any process, it is not sufficient to build links, it individual characteristic in a living being, if needs to be supported by a multi-facetted taken in isolation, could have been strategy. First, the education environment “tailored” through the natural selection must continually create a desire to process. Every genetic character should then understand and to search. Then it must make have an adaptive utility, including the eye the learner stop and think, shake him up; colour, the appendix and a U-shaped tongue. suggest to him that what he thinks may Many neutral characters exist; they do not differ from what really is. Multiple affect descendants. Some genes are also confrontations are necessary, either between pleiotropic; they affect several characters at students or with reality (observations, a time. An advantageous mutation actually documentation, investigations...). Thinking brings along other characteristics, useless on aids (metaphors, images, words or their own. Also, the adaptation theory drawings), reference points (organizational doesn’t mean that it is the most efficient
Biology International Vol. 47 43 Giordan
character which has been selected, but rather Aroua, S., M. Coquide, & S. Abbes. (2002). the most « optimal »one at a specific time “L'évolution biologique : conceptions within the prevailing conditions. et rapport au savoir d'élèves tunisiens.” Furthermore, one should not consider this In A. Giordan, J.L. Martinand & D. concept from the genealogical point of view, Raichvarg (Éds.), Actes des XXIVes but rather from a phylogenetic one; this Journées internationales sur la means that we should not think « succession communication, l’éducation et la of individuals » but rather « genetic pool culture scientifique et industrielle. 265- within species » because species are not 268. descendants from one another. Bishop, B. A. & C. W. Anderson. (1990). At the same time, it is important to re-visit “Student conceptions of natural the mechanisms question; the synthetic selection and its role in evolution.” theory based on «mutation-selection» Journal of Research in Science appears too restrictive. Evolution is Teaching 27 (5): 415-427. dependent on other processes which try to change the allelic genes frequency within Cobern, W.W. (1994). “Point: Belief, populations: genetic engineering, genetic understanding, and the teaching of strangulation, genetic flow, genetic drift, evolution.” Journal of Research in migrations; the environment, sexual Science Teaching 31 (5): 583-590. reproduction, embryonic developments (with the “Maestro” genes) are just as Crawford, B. A, et al. (2005). “Confronting involved in the natural selection. On the prospective teachers’ ideas of other hand, the proven symbiotic and evolution and scientific inquiry using epigenetic processes - still not well known – technology and inquiry-based tasks.” are still too under-estimated. Journal of research in science teaching 42 (6): 613-637. At last, it is necessary to ask ourselves about the epistemological status to this theory, Dagher, Z.R., & S. Boujaoude. (2005). specifically what we call: determinism. The “Students’ perceptions of the nature of history of Life is of course full of random evolutionary theory.” Science events. Each of them is predetermined, Education 89: 378-391. however the number and the interactions between this set of random events which Demastes, S., Good, R., & Peebles, P. took place within the micro and macro- (1995). “Students’conceptual evolution is so enormous that the history of ecologies and process of conceptual life could never take the same path twice. change in evolution.” Science Evolution is only a succession of Education 79 (6): 637-666. contingencies; which doesn’t make it any less scientific; the same can be said of Duveen, J., & J. Solomon. (1994). “The meteorology and quantum physics. great evolution trial : Use of role-play in the classroom.” Journal of Bibliography Research in Science Teaching 31 (6): Aroua, S., M. Coquide, & S. Abbes. (2001). 575-582. “Les rapports d'élèves tunisiens à l'évolution biologique et leurs Ferrari, M., & M-T.H. Chi. (1998). “The référentiels d'argumentations.” In Actes nature of naive explanation of natural des Deuxièmes Rencontres ARDIST - selection.” The international journal Actualité de la recherche en didactique of science education 20: 1231-1256. des sciences expérimentales et des techniques. 177-187.
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Fortin, C. (1990). “L’évolution : un mythe, une doctrine ou une science?” In A. Jackson, D.F., et al. (1995). “Heart and Giordan., JL. Martinand., D. minds in the science classroom: The Raichvarg. (Eds.), Actes des XIIes education of a confirmed evolutionist.” Journées internationales sur la Journal of Research in Science communication, l’éducation et la Teaching 32 (6), 585-611. culture scientifique et industrielle. 357-362. Jeffery, K.R. (1994). “A study of the presence of evolutionary protoconcepts Fortin, C. (1994). “Du bon usage des in pre-high school textbooks.” Journal conceptions en biologie de l'évolution” of Research in Science Teaching 31 in Giordan A. Conceptions et (5): 507-518. connaissances. Bern: Peter Lang. Jensen, M.S. & F.N. Finley. (1995). Galiardi, R. & A. Giordan. (1987). “L’idée “Teaching evolution using historical d’évolution.” In A. Giordan. (s.dir.), arguments in a conceptual change Histoire de la biologie, Tome 2, Chap. strategy.” Science Education 79 (2): 4, pp. 217-279. Paris: Technique & 147-166. documentation-Lavoisier. Jimenez Aleixandre, M.P. (1994). “Teaching Giordan, A., & Y. Girault. (éds.) (1996). The evolution and natural selection : A look new learning models; their at textbooks and teachers.” Journal of consequences for the teaching of Research in Science Teaching 31 (5): biology, health and environment. Nice: 519-535. Z'éditions. Lawson, A.E., & W.A. Worsnop. (1992). Giordan, A., (1998), Apprendre!. Paris: “Learning about Evolution and Belin. rejecting a belief in special creation : Effects of reflective reasoning skill, Geraedts, C. L. & K. T. Boersma. (2006). prior knowledge, prior belief and “Reinventing natural selection.” religious commitment.” Journal of International Journal of Science research in science teaching 29 (2): Education 28 (8): 843-870. 143-166.
Galangau-Quérat, F. (1990). “Les Mathy, P. (1996). Les choix représentations de la théorie de épistémologiques, les idéologies et les l'Évolution.” In A., Giordan, J.L., valeurs dans les manuels de biologie : Martinand, et D., Raichvarg (éds.). production d'instruments d'analyse Actes des Xlles JIES. 309-314. pour la formation des enseignants. Genève: Université de Genève, thèse Hallden, O. (1988). “The evolution of the de doctorat. 273 pp. species : Pupil perspectives and school perspectives.” International Journal of Passmore, C., & J. Stewart. (2002). “A Science Education 10 (5): 541-532. modelling approach to teaching evolutionary biology in high schools.” Ingram, E. L. & C. E. Nelson. (2006). Journal of Research in Science “Relationship between achievement Teaching 39 (3): 185-204. and student’ acceptance of evolution and creation in an upper-level Quessada, Mp., F. Munoz, P. Et Clement. evolution course.” Journal of research (2007). “Les conceptions sur in science teaching 43 (1): 7-24. l’évolution biologique d’enseignants du
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primaire et du secondaire de douze André Giordan pays (Afrique,Europe et Moyen Orient) is a biologist varient selon leur niveau d'étude. specialized in Congrès international Actualité de la the physiology Recherche en Education et en of regulation as Formation.” Actes in Actualité de la well as in Recherche en Education et en science didactics Formation, Strasbourg. and epistemology. Former primary and secondary school teacher, former youth club Rudolph, J.L., & J. Stewart. (1998). leader, he is currently Professor at the “Evolution and the nature of science: University of Geneva, where he founded the On the historical discord and its Laboratoire de didactique et épistémologie implications for education.” Journal of des sciences (LDES). He developed research Research in Science Teaching 35 (10): on the elaboration and appropriation of 1069-1089. scientific and medical knowledge and is particularly recognized for his original Sandoval, W.A., & K. Morrison. (2003). learning model, the allosteric learning model “High school students’ ideas about and for his physionical approach which theory change after a biological inquiry introduced new ideas to the field of learning unit.” Journal of Research in Science companies. Teaching 40 (4): 369-392. Immediate past president of the Commission Scharmann, L.C. (1992). “Teaching of Biological Education (IUBS), he is also evolution: Understanding and apling consultant for numerous international the nature of science.” Journal of organizations and companies, author or Research in Science Teaching 29 (4): editor of thirty books and of popular science 375-388. articles. Moreover, he participates in the conception and implementation of museums, Van Praet, M. (1989). “La non-acquisition exhibits, television programs, teaching des notions de temps et d’espèce : deux materials, and multimedia productions in the entraves à l’enseignement de la théorie areas of science, health and the environment. de l’évolution.” In A. Giordan, J.-L. Martinand & D. Raichvarg (Éds.), Actes des XIes Journées internationales sur la communication, l’éducation et la culture scientifique et industrielle. 357- 362.
Teaching and communicating Evolution 46
Threshold Concepts in Learning Biology and Evolution
Pauline M. Ross1, Charlotte E. Taylor2, Chris Hughes3, Noel Whitaker3, 3 3 2 Louise Lutze-Mann , Michelle Kofod , Vicky Tzioumis
AFFILIATIONS 1Pauline Ross , College of Health and Science, University of Western Sydney, Australia Locked Bag 1797, Penrith South DC, 1797 2Charlotte Taylor, Vicky Tzioumis, University of Sydney, Sydney 2006, Australia 3Chris Hughes, Michelle Kofod, Louise Lutze-Mann, Noel Whitaker, University of New South Wales, Sydney, 2052, Australia
Students in higher education often have misconceptions (which may have arisen prior to and/or because of formal instruction) that affect their academic progress. A theoretical framework entitled “threshold concepts” (Meyer and Land 2003, 2005) may provide academics with a powerful heuristic to help more students to pass through previously troublesome and inaccessible conceptual gateways. Meyer and Land (2005) describe “threshold concepts” as seminal ideas within a discipline that, once grasped, make the learner feel they are ‘crossing through a portal’. These are transformative, irreversible and integrative experiences typified by cognitive and ontological shifts within students’ minds, often accompanied by an extension of students’ scientific language. Although any one individual concept is not necessarily troublesome to all students, within any one
discipline, there may be some pieces of fundamental, tacit knowledge which have become “assumed understanding” and thus ritualised by students and teachers. “Threshold concepts” may also have extrinsic properties - what is a threshold for one student, may not be a threshold for another. In this Australian Learning and Teaching Council-funded study, empirical evidence from students at three major universities, with differing cultures and student characteristics, and from academics (in Australia and overseas) was used to identify a web of potential “threshold concepts” in Biology, which include the topics of ‘evolution’ and ‘equilibrium’. It may be that once students cross a threshold and have a deeper understanding of some seminal concepts, they can transfer this way of thinking to aid in crossing thresholds in other contexts when encountering difficult concepts.
How do we understand biological concepts? 2007; 2008; Ross & Tronson, 2004; 2007 ; Köse, A number of studies have surveyed undergraduate 2008) and the scientific processes of hypothesis and and postgraduate students and academic staff, to null hypothesis testing (Taylor and Meyer 2009). determine which biological concepts are most Although there is general consensus on key areas difficult to learn and to teach (Taylor 2006; Taylor and to some extent agreement on what makes them 2008; Ross et al., 2009). In response, biology difficult it has been more of a challenge to identify academics and students have identified the content the ways in which difficulties arise and, more areas of cellular metabolic processes (including challenging still, the ways in which we might photosynthesis, respiration and enzymes), osmosis approach teaching these difficult areas. (diffusion and active transport), genetics (protein synthesis, cell division, DNA) homeostasis, A recent development in the study of student evolution (e.g. Gabel, 1994; Wandersee et al., 1994; learning has proposed the notion of “threshold Brown, 1995; Canal, 1999, Griffard, 2001, Taylor, concepts” i.e. concepts which are central to the
Biology International Vol. 47 47 Ross et al mastery of a specific discipline, and which many students find difficult to learn and teachers find difficult to teach (Meyer & Land 2003, 2005). It is the failing to, and then grasping of, these threshold concepts which becomes a rite of passage from the novice to expert within their discipline. Once understood, threshold concepts open a door within the discipline which is akin to passing through a portal or conceptual gateway to a previously inaccessible and initially perhaps troublesome way of thinking about something. These conceptual gateways or thresholds are characterised as being transformative (occasioning a significant shift in the perception of a subject), irreversible (unlikely to be Table 1. A model for the development of conceptual understanding in forgotten or unlearned) and integrative (exposing Biology (from Ross et al., 2009) the previously hidden interrelatedness of something) (Meyer & Land, 2005). This transformed internal It has been suggested that to identify threshold view is typified by a cognitive and ontological shift concepts, or that which is currently left tacit in the (Meyer, personal communication), often teaching/learning nexus (Davies, 2006), we need to accompanied by an extension of the student’s use of lift our eyes above the particular (Perkins, 2006) to language (Meyer & Land, 2005). determine which concepts operate in a deep integrating way in the discipline. These tend to be By integrating this novel view of understanding simultaneously taken for granted by the discipline concepts with our knowledge of students and experts, and are rarely made explicit to the novice academic staff we have proposed that threshold (Davies, 2006). In biology enquiry into these concepts in biology are not the difficult content thresholds requires analysis of areas which are not areas identified as troublesome, but constitute more necessarily identified as traditional core curriculum abstract ideas which are fundamental to thinking as or content, but which underpin the way in which we biologists, namely; energy and energy think and practise as biologists (McCune and transformation, variation, probability and Hounsell 2005, Taylor 2006, 2007; Ross et al. randomness, proportionality such as surface area to 2006). volume ratios, linkage of the subcellular (submicroscopic) with the macroscopic, temporal The bicentenary year of Charles Darwin’s and spatial scales and equilibrium (Table 1). For contribution to biological thinking, provides an example; protein synthesis is frequently identified appropriate forum to further explore this challenge as a difficult troublesome content area in biology, in enhancing understanding of biological concepts, but that does not automatically make it a threshold using a case study on evolution, which will allow concept. To overcome the threshold needed to the development of more appropriate learning and understand protein synthesis students need to teaching experiences. We argue that the concepts of operate and integrate simultaneously several evolution is not itself a threshold concept, as hierarchical processes at sub cellular and defined above, but consists of a complex of submicroscopic scales while incorporating the interconnected threshold concepts including an dynamism and three dimensionality of cell identification that physical and genetic variation processes. exists within a population, understanding that the variation in physical characteristics is inherited by offspring as discrete units and that a time scale involving millions of years of biological life is the context of this theory.
Threshold Concepts in Learning Biology and Evolution 48
Is evolution a threshold concept? threshold-crossing step occurs when there is Taylor and Cope (2007) analysed first year integration of discipline concepts and the undergraduate responses (n=200) to the following emergence of a commonality or web of conceptual question “Much of Biology is about the way change. organisms have become adapted to their environment through the process of evolution. Level of Meaning Process Typical student Under- response What do you know about adaptation? “, and posed standing the question “What is the experience of evolution 1 Species change Change It is a process that described here?” A phenomenographical approach takes a long time and occurs through was used to identify levels of student understanding necessity for and a matrix developed (Table 2). Levels 1 and 2 survival corresponded to the least sophisticated level of 2 Species change and Change + Through natural adapt to their adapt to selection, organisms understanding, while levels 5 and 6 were the most environment over a unchanging adapt to their sophisticated in a hierarchical ordering. Levels 5 long period of time environment environment and and 6 thus incorporated the meaning and Lamarck? thrive 3 Species adapt over Change + Adaptation occurs characteristics of the preceding levels of time in response to adapt + due to a change in understanding. changes in the changes in the environment. It environment, those environment can occur gradually fittest will survive + Fittest or by punctuation. A key characteristic inherent in each of these levels and others will die of understanding was a change or time conception. out. 4 Change over time Change + I understand In the lower level responses, species changing or leading to time adaptation as change was described, while in the higher level differences at natural section, responses, the scale at which the change occurs was species level preserving and improving genes discussed. The variability, both physical and while benefit the genetic, within a population, which underpins the organism over time theory of evolution, was absent in both simple and 5 Changes in species Change + Adaptation is the response to adapt+ process of a species more complex student responses. This analysis environmental changes in of organisms thus identified the process of change and a temporal changes have environment+ changing genetic basis genetics physiologically, component as a basic concept (as defined in the structurally or progression described in Table 1), the link between physically in the process of natural selection and genetic response to their environment. It underpinning as a discipline concept (see Table 1) occurs over many and therefore questioned whether these could be generations as defined as true threshold concepts. Discipline Darwin proposed. Adaptation is the conceptual changes (Davies & Mangan 2007) are result of natural those concepts where there is an integration of the selection of a theoretical view within the discipline including a species. 6 Population Change + Natural selection transformation. In biology, for example, students responses to changes in agents act on the might have a basic concept of change of species and changes in the environments population. Those environment, over + time scale who survive do so adaptation, but can only integrate and transform this time scales by chance (the content within the theoretical perspective of an feature that helps organism being best suited or adapted, surviving to them survive is there purely by reproduce. chance) and give them an adaptive Similarly a basic conceptual change of physical advantage”. It doesn’t work the inheritance of characteristics is needed to integrate other way i.e. the and transform the processes whereby these physical animal changing physically to suit the characteristics which are best suited are selected for environment e.g reproductively. Although these are integrative and Lamarck theory. transformative experiences, the acquisition of the Yeah I understand the theory of natural discipline type of conceptual change, does not selection. require irreversibility. The irreversible and Table 2 Levels of student understanding and responses relating to the concept of evolution Biology International Vol. 47 49 Ross et al
Our studies therefore suggest that the threshold demands of biology, being particularly challenging concepts underlying an understanding of evolution at the basic and discipline stage (Table 1), often involve an identification that physical and genetic creating barriers. For many students, language variation exists within a population, that the acquisition is difficult because the language used to variation in physical characteristics inherited by describe specific biological conditions becomes offspring are discrete units, reproductive success, confused with the students’ natural language form randomness and that a time scale involving millions (Meyer & Land, 2003; 2005). For example, there is of years of biological life is the context of this an everyday meaning to “adaptation” while the theory. They are threshold concepts because they scientific construct is specific and relates to a are integrative, transformative and once acquired complex web of biological Darwinian perspective. develop an irreversible way of thinking within the Also, many students and staff tend to concentrate on student. Thus we find that many of the difficult acquiring the language of biology, rather than areas in biology, as identified in our survey, (and meaning, cognitively overloading students, listed in column 1 of Table 1) have a series of exacerbating and increasing the intensity of the threshold concepts in common (described in column language barrier, and preventing development of the 6 of Table 1). For example, the concept of holistic viewpoint needed to acquire threshold variability is key to several content areas including concepts. Paradoxically, however, language, ecology, evolution and genetics, while an complexity, dynamism and dimensionality are key understanding of energy transformations and threshold concepts in biology. dynamism are some of the threshold concepts or “big ideas” critical in cellular metabolic processes Difficulty in understanding threshold concepts may including enzyme action and ecology. The concepts leave a student in a state of liminality where they of variability and probability underlie understanding get “stuck” (Perkins 1999; Meyer & Land, 2006). in genetics, evolution and a number of cross Such liminal or “stuck” places prevent the learner disciplinary areas (e.g. quantum mechanics), as does from undergoing a transformation which may be the process of empirically combining factors in a integrative and irreversible extending their scientific investigation (hypothesis creation) or understanding of formal and symbolic language genetic recombination. while at the same time paradoxically characterising the change (Meyer & Land 2005). If Meyer and How can we characterise students’ Land are correct and it is these threshold concepts understanding of threshold concepts? that are the real drivers for the core concepts and We acknowledge that there is certain to be variation discourses within a discipline, then things that must in student understanding within any cohort so that be made explicit to students if they are to think what is a threshold concept for one student will not effectively in the ways of that discipline. be for another. There is a general expectation that students entering university have the background Implications for the teaching of evolution knowledge and understanding of basic and Using the heuristic of threshold concepts allows us discipline concepts in biology (Table 2 level 5-6 in to develop an understanding of the continuum in understanding), although university lecturing staff conceptual learning between the novice and expert are often surprised that they do not and are within our discipline. Our current study has operating below the level of threshold concepts demonstrated that a re-evaluation of the curriculum (Table 1). The reality is that if students enter tertiary and our approach to teaching biology may be in biology without senior levels of biology in their order. For example, we are examining where schooling they are likely to have only fragmented should we be spending our energies as teachers of basic biological concepts, while those with high biology? If we continue to spend our entire time levels of achievement in biology at senior levels with the basic and discipline concepts (as described may have some discipline biological concepts. in Table 1), how will our students be able to develop the tools or facility with threshold concepts In addition, the acquisition of language and and to engage with troublesome content? understanding of language, in context, is critical Alternatively if we shift our focus to the more within the discipline of biology. The linguistic abstract threshold concepts, perhaps students will Threshold Concepts in Learning Biology and Evolution 50
have a poorer progress and performance in basic Griffard, P. B. (2001). “The two-tier instrument on and discipline concepts? Initial discussions with photosynthesis: what does it diagnose?” biologists have shown that these arguments strike a International Journal of Science Education 23 chord and have stimulated individuals to reflect on (10): 1039–1052. and make changes to their teaching. At the same Köse, S. (2008). “Diagnosing student time we are analysing further student responses to misconceptions: using drawings as a research questions eliciting responses relating to specific method.” World Applied Sciences Journal 3 (2): understanding of threshold concepts. We are 283–293. confident that the surfacing of the tacit threshold game within disciplines, through analytic McCune, V. & D. Hounsell. (2005). “The discussion, deliberative practice and alignment of development of students’ ways of thinking and the threshold with instructional approaches will practising in three final-year biology courses.” make a significant difference to the teaching and Higher Education. 49: 255–289. learning within disciplines. Meyer, J.H.F. & R. Land. (2003). Threshold Acknowledgements Concepts and Troublesome Knowledge: This study is being undertaken collaboratively by Linkages to Ways of Thinking and Practising academics from three universities in Australia: the within the Disciplines. Enhancing Teaching- University of Sydney; the University of New South Learning Environments in Undergraduate Wales; and the University of Western Sydney, Courses. Occasional Report 4. funded through the Australian Learning and Teaching Council (ALTC). Meyer, J.H.F. & R. Land. (2005). “Threshold concepts and troublesome knowledge (2): References Epistemological considerations and a conceptual Brown, C. R. (1995). The Effective Teaching of framework for teaching and learning.” Higher biology. Longman: London, 99–119. Education 49: 373–388.
Canal, P. (1999). “Photosynthesis and ‘inverse Meyer, J.H.F. & R. Land. (2006). “Threshold respiration’ in plants: an inevitable concepts and troublesome knowledge: an misconception?” International Journal of introduction” in J. H. F. Meyer & R. Land (Eds), Science Education 21 (4): 363–371. Overcoming Barriers to Student Understanding: Threshold concepts and troublesome knowledge. Davies, P. (2006). “Threshold concepts: how can Routledge: Abingdon, 3-19. we recognise them?” In Overcoming Barriers to Student Understanding: Threshold concepts and Perkins, D. (1999). “The many faces of troublesome knowledge. (J. H. F. Meyer & R. constructivism.” Educational Leadership. 57 (3): Land, Eds.). Routledge: Abingdon, 70-85. 6–11.
Davies, P. & J. Mangan. (2005). Recognising Perkins, D. (2006). “Constructivism and Threshold concepts: an exploration of different troublesome knowledge.” In Overcoming approaches. Working Paper 2, ETC Project, Barriers to Student Understanding: Threshold Staffordshire University. concepts and troublesome knowledge. (J. H. F. Meyer & R. Land, Eds.). Routledge: Abingdon, Davies, P. & J. Mangan. (2007). “Threshold 33-48. concepts and the integration of understanding in economics. “ Studies in Higher Education 32 Ross, P. M. & D. Tronson. (2004). “Towards (6): 711–726. conceptual understanding: bringing research findings into the lecture theatre in tertiary Gabel, G.L. (1994). Handbook of Research on science teaching.” In Proceedings of Scholarly Science Teaching and Learning: A Project of Inquiry into Science Teaching and Learning the National Science Teachers Association. Symposium. UniServe Science: Sydney, Macmillan Publishing Company: New York. Australia, 52–57. Biology International Vol. 47 51 Ross et al
Ross, P. M., D. Tronson, R. J. Ritchie. (2006). Wandersee, J. H., J. J. Mintzes, & J. D. Novak. “Modelling photosynthesis to increase (1994). “Research on Alternative Conceptions conceptual understanding.” Journal of in Science” in Handbook of Research on Science Biological Education 40 (2): 84–88. Teaching and Learning: A Project of the National Science Teachers Association (G.L. Ross, P. M. & D. Tronson. (2007). “Intervening to Gabel, Ed.). Macmillan Publishing: New York. create conceptual change.” UniServe Science Teaching and Learning Research Proceedings. 89–94.
Ross, P. M., D. Tronson, R. J. Ritchie. (2008). “Increasing Conceptual Understanding of Glycolysis & the Krebs Cycle using Role-play.” The American Biology Teacher 70 (3): 163–168.
Ross, P. M., C. E. Taylor, C. Hughes, M. Kofod, N. Whitaker, L. Lutze-Mann. (2009). “Threshold concepts: challenging the culture of teaching and learning biology” In Threshold Concepts: from theory to practice. (J.H.F. Meyer, R. Land, and C. Baillie, Eds.). Sense Publishers.
Taylor, C. (2006). “Threshold concepts in biology: Do they fit the definition?” In Overcoming Barriers to Student Understanding: Threshold concepts and troublesome knowledge. (J.H.F. Meyer & R. Land, Eds.). Routledge: Abingdon, 87-99.
Taylor C.E. (2008). “Threshold concepts, troublesome knowledge and ways of thinking and practicing - can we tell the difference in Biology?” In Threshold Concepts in the Disciplines (R. Land, J.H.F. Meyer, and J. Smith, Eds.). Sense Publishers: Rotterdam, 185- 197.
Taylor, C.E. & C. Cope. (2007). “Are there multiple thresholds in the concept of evolution, and can they be identified using dimensions of variation?” In Proceedings of the Symposium Science Teaching and Learning Research, September 27 & 28, 2007, UniServe Science: Sydney, 101-106.
Taylor C.E. and J.H.F. Meyer. (2009). “The testable hypothesis as a threshold concept for biology students” In Threshold Concepts: from theory to practice. (J.H.F. Meyer, R. Land, and C. Baillie, Eds.). Sense Publishers.
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Pauline Ross is an outstanding Charlotte Taylor educator in science, a 2009 has degrees in recipient of an Australian botany, tropical Learning and Teaching Council ecology and higher (ALTC), Australian Award for education, and University Teaching (AAUT), a carried out field 2008 ALTC citation for an research in plant- outstanding contribution to animal interactions student learning, a 2007 in Malaysia before University of Western Sydney Excellence Award in arriving in Australia. She is currently the Associate teaching and four other university and national Dean for Learning and Teaching in the Faculty of awards for teaching excellence and a 2008 Science. Her research is focused on an integration Australian Award for Excellence in publication of of urban ecology, scientific literacy and biodiversity the textbook, New South Wales Biology (2007) education, and work with the Birds Australia Birds published by MacMillan. She is an Associate in Backyards project was recently awarded the Professor and Assistant Associate Dean (Learning national Eureka Prize for Environmental and Teaching) at UWS, and has extensive Sustainability Education. Charlotte’s current experience in science curriculum development in research projects are looking at how students, and Australia and overseas, known for innovation, schoolchildren, understand difficult biological creativity and inquiry into the teaching research concepts and cross ‘learning thresholds’. The nexus and conceptual understanding. Her research projects are now moving these investigations into and teaching practice is firmly grounded in the virtual 3D learning environments. Her research scholarly learning and teaching literature. Her students work across a wide range of topics, from current learning and teaching projects include the ecology of urban birds (parrots, mynas and “Threshold concepts: challenging the way we think noisy miners) to the ecological literacy of and learn in biology”, an ALTC project with the kindergarten children. She is currently University of Sydney and University of New South collaborating on the international Encyclopedia of Wales. Pauline is also actively engaged in projects Life project at Harvard University to develop determining the impact of climate change on marine biodiversity learning activities for schools, organisms and ecosystems with her postgraduate universities and public education programs. and postdoctoral students. Vicky Tzioumis is a Project Officer at the University of Sydney, working on an educational research project into the definition of a Threshold Concept in Biology. She has a PhD in marine ecology (University of Sydney) and a broad knowledge of the natural sciences. She has extensive experience in editing scientific papers and reports for publication in International Journals. She has managed interdisciplinary projects involving the scientific community within NSW Universities and State and Federal Government Departments.
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Chris Hughes is an Associate Louise Lutze-Mann is a Professor in the Medical Senior Lecturer in the School Education and Student Office of Biotechnology and and the School of Public Biomolecular Sciences and the Health and Community Academic Coordinator of Medicine at UNSW. He has a Learning and Teaching multidisciplinary background Enhancement for the Faculty in the sciences and the of Science at the University of humanities, and a doctorate in NSW. She has been involved adult education. He has over in curriculum development 30 years of experience in curriculum and teaching within the School, focusing on development. For the last nine years Chris has been the rationalization of courses, the introduction of working on the undergraduate Medicine Program at technology and the embedding of graduate UNSW, focusing on the program and course attributes. Louise spent 2002-03 working on the structures, assessment, and information technology development of the curriculum, policy and systems. Chris convenes the first phase of this procedures for a new university for the California program and tutors in medical ethics. His research State University System and was Chair of the focuses on medical education, particularly on Academic Senate. Apart from threshold concepts, assessment systems and the use of student generated her research interests are the development of novel resources. cancer chemotherapeutics and the engagement of students in learning.
Noel Whitaker is a senior lecturer in cell and cancer Michelle Kofod has a biology in the School of Bachelor of Science Biotechnology and (Honours) degree from Biomolecular Sciences and is the University of Associate Dean Sydney, and holds an (Undergraduate Programs) in Associate Diploma in the Faculty of Science, Information Technology UNSW. He has received (Instructional Media) and a Graduate Certificate in Education prizes (including an University Learning and Teaching at UNSW. She ALTC citation and Faculty Teaching award) and has been at the UNSW since 1993 and involved in educational fellowships. He has established a numerous projects across the university including number of intra and intra University Science the development of education technology, graduate Education Networks. He has carried out a number attributes mapping, e-portfolios, peer mentoring and of initiatives including University curriculum tutor training. In 2006 she was awarded a Carrick development and curriculum mapping for the Citation Award for Outstanding Contribution to Faculties of Science and Medicine. His research Student Learning. In 2007- 2008, Michelle held the interests are viruses causing cancer and teaching position of Australasian Countries Regional Co- students to think like scientists. Vice President for the International Society of the Scholarship of Teaching and Learning (ISSOTL). Her current role is Associate Director - Global Education Program UNSW International.
Threshold Concepts in Learning Biology and Evolution 54
Human Natures
Kim Sterelny
Philosophy & Centre for Macroe volution and Macroecology; Australian National University and Victoria University of Wellington
Two Framing Ideas about Human years (and especially over the last 200,000 Evolution. years) there has been, and continues to be, Recent work on the evolution of the a pulse of increasing technological human mind has been framed by two key innovation. Along with these ecological, ideas. One is that human evolutionary social and behavioural changes, there have change has been rapid, extensive and been changes in morphology (most driven by some form of positive feedback. obviously, in relative brain size), life Evolutionary biologists were surprised by history and family organization (Diamond the genetic distance between humans and 1992; Mithen 1996; Klein 1999; Klein and the two chimp species, and by the Edgar 2002). Tellingly, this pattern has not relatively recent divergence dates been mirrored in other lineages. We would indicated by molecular clocks. They were expect to see mammalian (or primate) surprised because humans seem so lineages changing in parallel, if the cognitively, behaviourally and even hominid trajectory was chiefly driven by morphologically unlike their closest kin. some external crisis. So while there may As Jared Diamond noted, three million have been an external trigger, the natural years ago hominids were relatively minor hypothesis is that hominid evolutionary elements of a rich East African change has been self-generated through mammalian fauna. Our closest living positive feedback. relatives are still restricted to narrow geographical ranges and specific The second idea is that routine human ecological settings. But the hominid cognitive competences have a high lineage has expanded both geographically information load. Ordinary adaptive and ecologically: our ancestors spread out decision-making depends on an agent of Africa and into many habitats very being sensitive to complex, subtle features different from the woodlands and of their environment. The information- savannahs of East Africa. Our population hungry nature of human action first size is vast. Coupled to this geographic, became apparent in thinking about demographic and ecological expansion, language (Pinker 1994). Language is at the our lineage has experienced an explosive core of the cognitive revolution in increase in tool use and co-operation. We psychology and of the most prominent are the only large mammal that routinely attempt to synthesise psychology and depends for essential resources on co- evolutionary theory, and no wonder. operation with non-relatives. Stone tools Language makes intensive demands on (simple flakes and cores) first appeared in memory. The different parties to a the hominid archaeological record about conversation must remember who said 2.5 mya. For perhaps two million years, what to whom. It also makes intensive hominids continued to use technology, but demands on attention. In a conversation, without there being much elaboration and you must do more than recall what has improvement. But over the last 500,000 been said: you need to be alert to the signs Human Natures 56 that conversation is going wrong. argued, a central element of Darwinism is Moreover, you will often have to do this to conceive of lineages as variable while also attending to your physical and populations, not as an essence whose social world, for often the point of talking phenotypic manifestation is blurred by is to co-ordinate joint action. Linguistic noise (Mayr 1976b; Hull 1986; Gould acts interface with, and are smoothly 1996c). There is no single human nature, integrated with, the rest of our lives. So manifested differently because of even without considering Chomsky’s differences of culture and environment. celebrated arguments for the unlearnability We are many, not one, and a changing of human language, we can see that our many at that. ability to use language seems almost miraculous: we must be instantly sensitive The Standard Model to a limitless array of features of our The standard model presupposes that some current circumstances. The same is true of trigger initiated increased levels of co- other competences. For instance, in much operation in early hominids. Perhaps, as social interaction we are effortlessly tuned Paul Bingham suggests, stone-throwing to the moods, intentions and beliefs of evolved as a tool for foraging and defense, others. If you have made some horrendous and was then exapted for social purposes, social blunder, it is almost impossible not because it reduced the costs of punishing to be aware of it. Yet since others obey those who take but do not give (Bingham norms of politeness in such situations, this 2000). But once co-operation became a awareness often depends on sensitivity to key feature of hominid lifeways, it induced small cues of posture, expression, tone of an arms race. Co-operation — especially voice; shifts in conversational focus and so when allied to specialisation and the forth. As with language, so with the skills division of labour — is an immensely of social navigation, bargaining and co- powerful adaptation. Agents acting ordination, acquiring and using together can secure resources, construct technology. Almost all of us acquire these technologies and defend territories that skills, but they depend on acquiring and would be utterly beyond any singleton deploying significant informational (Skyrms 2003). But often the profit of co- resources. operation is not contingent on every member of an alliance paying the full costs There is a standard model of how these of co-operation, and hence there is a framing ideas should be developed: the temptation to defect, to secure a share of feedback loop is driven by the increasing co-operation’s profits while avoiding its complexity of human social environments, costs (Axelrod 1984; Skyrms 1996). Co- and by the problems that complexity operation is thus risky as well as causes for co-operation management. profitable; and so co-operators must be Adaptive response to our complex vigilant. Vigilant co-operation selects for environment depends on innate, evolved, intelligence. But as others become more special purpose cognitive mechanisms, for intelligent, defection threatens to become it is only such mechanisms that enable us increasingly well disguised. As co- gather and deploy the information on operating groups become built from which action depends. I accept both these increasingly intelligent agents; as co- framing ideas —positive feedback loops operating groups become increasing are indeed critical in driving hominid differentiated through division of labour, evolution, and much routine human action and as they become larger, effective has a high information load. But I am vigilance becomes ever more difficult. Yet sceptical about the way these faming ideas co-operation is too essential to abandon. are developed in the standard model. The Hence selection for vigilance is selection rest of the paper defends this scepticism for still higher intelligence; this in turn and outlines an alternative; an alternative ramps up both the potential profits of co- that fits better with one core feature of operation and its potential risks Darwinian thinking. As Ernst Mayr, David (Humphrey 1976; Flinn, Geary et al. Hull and Stephen Jay Gould have all 2005).
Biology International Vol. 47 57 Sterelny
The key idea, then, is that there is a are efficient because they come pre- positive feedback loop between individual equipped with much of the information intelligence and social complexity. As a they need. We are born knowing what consequence of this loop, hominid social human languages are like, what human worlds become ever more complex. We minds are like, what human social worlds have many needs, so exchange is complex. are like. Children need to learn the specific Sexual and social alliances are crucial to moral norms of their community. But they fitness and difficult to negotiate: alliance do not need to learn what a moral norm is, formation is high-risk-high reward or that their community will have norms decision making. Hominid social worlds which they must internalise (Hauser expanded in size and organisational 2006). These devices evolved in response complexity. This expansion in size and to the distinctive, independent, and re- complexity made co-ordination more occurring problems of Pleistocene difficult, and perhaps as a consequence, foragers. We all have the same set: devices communication became more important to adapt us to use language, track others’ (reputation becomes a key social asset); mental states, to recognise violations of more elaborate, and dependent on arbitrary rules and agreements; to recognise and signals). The informational prerequisites respond to moral codes. Pathology (and of successfully negotiating an increasingly perhaps sex differences) excepted, humans complex social world increase (Dunbar have a common cognitive design. 2003). I am skeptical (Sterelny 2003; Sterelny The second key idea of the standard model 2007). The modular, nativist explanation is that these demands are discrete and of behavioural competence presupposes predictable. For example, all agents must that the information structure of human be able to read intention from gesture, selective environments is stable. If the posture, voice and similar cues. But the information a child needs about her social cues needed for intention-reading do not world is stable over evolutionarily overlap significantly with those needed significant time frames, selection can build (say) to evaluate bargains in material that information into human minds. Not exchange. So according to the standard otherwise. Some domains are stable. model, ordinary human action involves There may be a naive physics module solving problems with a high information ((Sperber, Premack et al. 1995; Pinker load. But the problems we need to solve, 2007). Humans, including young humans and the information we need to solve those and perhaps only humans (Povinelli, with problems, are relatively constant over et al. 2000), interpret interactions between evolutionary time. This idea has lead to everyday physical objects in terms of the famous “massive modularity” hidden forces. Hominids have long been hypothesis, most eloquently defended in selected for competence in making and (Pinker 1997), but first systematically wielding tools, and the causal properties of articulated in (Barkow, Cosmides et al. sticks, stones and bones do not change. So 1992). On this hypothesis, our minds are it would be no surprise if this competence ensembles of innately equipped special depended on an innate module for purpose devices; devices which adapt us to understanding causal interaction. Material the challenges posed to our foraging technology is a plausible example of a Pleistocene ancestors; challenges which discrete, stable, and fitness-critical largely, but not entirely, persist today. domain. According to the massive modularity hypothesis, the distinctive character of This example, however, is the exception human intelligence does not primarily rather than the rule. We have not evolved depend on domain general capacities to in socially, cognitively, or biologically learn and to solve problems. Rather, our constant environments. In part, this is a minds are integrated arrays of devices consequence of Intensifying climate each of which solves a particular problem change destabilising hominid with remarkable efficiency. These devices environments (Potts 1998). But most
Human Natures 58 importantly, human action causes major cognitive evolution. Each agent has an changes in human social, physical and interest in maximising his/her return from biological environments. For example, we co-operation while minimising investment often see in the foraging record a transition in co-operative activities. This sets up a from specialisation in large to medium vigilance requirement that becomes animals to taking a much larger range of steadily more challenging, as others individually less valuable items (this is become more able and social worlds known as the “broad spectrum revolution” become more complex. However, while (Stiner 2001)), This is likely to be the policing defection is a prerequisite of signature of humans exhausting their stable co-operation, this picture overstates favoured resources, forcing economic, the problem in small scale social worlds of technological, and social re-organization identifying cheats, and understates the on an expanding population. This is one informational challenge of co-ordination; example amongst many: migrating from of making co-operation work in an one habitat to another, likewise, forces environment of mutual trust (Calcott lifeway re-organization. There is no reason 2008). to suppose that inter-group relations, group size, economic organization, or the In a village, everyone knows who the extent and character of social hierarchy arseholes are. In part, this is due to were roughly constant before the invention effective gossip networks (and hence relies of farming. Yet these factors determine the on late-evolving communicative capacities social problems agents face. If the (Dunbar 2003)). But it depends as well on structure of human social worlds varies an ancient feature of human economic life: over space and time, the informational our evolution as social foragers (Sterelny resources need to lead a successful forager 2007). Over deep time, there has been a life were not a stable target onto which revolution in hominid foraging and selection could lock. But even if forager resource acquisition. Our lineage has societies were essentially all alike, we now evolved from being omnivorous marginal live in a world unimaginably different scroungers to being dominant predators; from that of the paleoforagers of ancient from being predator targets to taking the Africa. If (as the massive modularity food from other predators (Stiner 2002). hypothesis suggests) adaptive response to There is considerable controversy about high load problems depends on innate this process: about its timing; about the specialisations designed for the world pf relative importance of scavenging and Pleistocene foragers, contemporary hunting; about role of plant foods and humans should suffer massively from small game in human diets; about the adaptive lag. We should be incompetent in invention of cooking and its role in human the face of informationally demanding evolutionary history (Marlowe 2005; novel problems. But we are not; few of us Marlowe 2007). But by around 200,000 suffer catastrophic fitness failures years bp, hominids had evolved into social threading our way through (say) LAX (a foragers exploiting high value, heavily novel environment if any is). We do not defended resources. Large and medium negotiate evolutionarily novel problems size game animals had become a key perfectly, but we negotiate them resource, and these were taken directly; surprisingly well. That is a crucial fact the they were not acquired by driving other massive modularity hypothesis does not predators from their kills (for in contrast to explain. Part of the explanation is that predator kills, prime adults were often novelty is not new. Our lineage has consumed). Large herbivores (buffalos, for repeatedly experienced demanding example) are neither easy nor safe to kill, environmental change, mostly induced by especially with short-range technology. So our own activities. this foraging mode depended on (i) informational resources. Hunting peoples An Alternative Model need intimate knowledge of the habits and The standard model identifies co-operation responses of their targets — especially management as they key driver of human their hard targets — and the resources and
Biology International Vol. 47 59 Sterelny dangers of the local terrain. (ii) They need effective as technology and technique technology, and the skills to use that improve across the generations. As social technology expertly. (iii) They need to co- foraging becomes more profitable, adults operate. Lone hunters or small parties can can more effectively support the next kill large animals once lethal standoff generation while they acquire skills and technology has been invented: spear- information. As with the standard model, throwers; bows; poison darts. But 200,000 the informational challenges of co- years ago, these innovations lay in the operation drive human cognitive quite distant future. Killing a Cape Buffalo evolution. But on this alternative model, with stone-tipped spears with reasonably the challenges are very different. safely would require groups to act together in a co-ordinated yet flexible way. I suggested above that human decision Humans were social hunters before they making is often adaptive, even though were individual hunters. good decision making depends on the acquisition and judicious use of significant Social foraging has both informational informational resources. Since such preconditions and consequences. Social decision making often takes place in novel foraging generates information: agents environments, our genes cannot predict the leak information about their character, environment into which we will be born. judgement and capacities when engaged in So high load problems cannot be solved by intimate, high-stress collective activity, pre-loading crucial information. especially when the activity persists for Competence in the face of evolutionarily days. On a three-day hike, you find out a novel problems often depends on skill. lot about your companions, especially if Skills are phenomenologically akin to the you get lost or the weather turns foul. That modules of the standard model: they are is true even when you have modern fast, automatic, and task specific. Without equipment and face no real danger. The the special training of professional greater the stress, discomfort or danger, linguistics, it is impossible to hear speech the more you and they learn. Collective in a familiar language as mere noise: I foraging would frequently involve stress, cannot but hear English speech as words, discomfort and danger, and shirkers and sentences, conversations. Likewise, I cheats would unambiguously identify cannot but see written English words as themselves. But collective foraging also words; I cannot see them as mere shapes. has informational prerequisites. Co- But reading is a response to a novel ordination depends on communication problem. The kind of communication (and perhaps planning as well). But it also writing makes possible is new: depends on rich, accurate local decontextualised, often one-off knowledge; on a detailed grip of the communication with strangers, sometimes natural history of target species; on locally displaced in space and time. So too is the made technology used with great medium involved. Once the capacity is expertise. No generation acquires these acquired, reading seems as natural as informational resources from scratch: the listening. But like other crucial but cognitive capital on which successful contingent skills, reading depends on a foraging depends is acquired by cross- long learning history in organized generation information pooling (Kaplan, developmental environ-ments. Hill et al. 2000; Robson and Kaplan 2003; Gurven and Hill 2006; Gurven, Kaplan et Humans, like many other organisms, al. 2006). The informational resources one modify their own environment and that of generation inherits will be modified (as the next generation (Odling-Smee, Laland conditions change and through innovation) et al. 2003). In our case, one important and transmitted for further modification to form of that modification is informational the next. High volume, high fidelity, inter- engineering (Sterelny 2003). Humans of generational cultural learning coevolves one generation act in ways that transform with social foraging. As its fidelity the learning environment of the next improves, social foraging becomes more generation. Cultural learning is obviously
Human Natures 60 central to human social life (Shennan based on a single human nature with a pre- 2002; Mesoudi, Whiten et al. 2006). But wired set of capacities and inclinations can most cultural learning is hybrid learning; it explain either our history or our current is culturally enhanced trial and error diversity. Human minds are as variable learning (Sterelny 2006). Very few and as various as the worlds we have humans acquire significant life skills just experienced and partially made. from instruction and demonstration; very few learn skills by unassisted exploration. References Human children are far from passive; they Axelrod, R. (1984). The Evolution of explore and experiment on their physical Cooperation. New York, Basic and social environment. But they often Books. explore environments which have been shaped to make it easier or safer for them Barkow, J. H., L. Cosmides, et al., Eds. to acquire critical capacities. Apprentice (1992). The Adapted Mind: learning is a good model of the form of Evolutionary Psychology and the cultural learning that explains our capacity Generation of Culture. Oxford, in the face of novelty. Apprentice learning Oxford University Press. is hybrid learning. It is learning by doing, but in supervised and enriched learning Bingham, P. (2000). "Human Evolution environments. Apprentices are assigned and Human History: A Complete tasks that are both appropriate to their Theory." Evolutionary Anthropology current skill levels, but which stretch 9 (6): 248-257. them, and which scaffold the acquisition of new skills. In their work they are Calcott, B. (2008). "The Other surrounded by props: tools; completed and Coooperation Problem: Generating partially completed artefacts; raw Benefit." Biology and Philosophy 23 materials in various stages of preparation; (2): 179-203. errors — examples of what can go wrong. Often they have sources of advise and Diamond, J. (1992). The Third demonstration from peers and near-peers Chimpanzee: The Evolution and as well as skilled craftsmen. There were Future of the Human Animal. New no Palaeolithic craft guilds akin to those of York: Harper Collins. early modern Europe, but there are quite striking similarities between skill Dunbar, R. (2003). "The Social Brain: transmission in formal apprenticeships and Mind, Language and Society in that in traditional society (Stout 2002). Evolutionary Perspective." Annual Such socially organised and adapted Review of Anthropology 32: 163- learning environments — environments 181. which marry the power of trial and error learning to that of cultural transmission — Flinn, M., D. C. Geary, et al. (2005). make possible the transmission of high "Ecological Dominance, Social fidelity, high volume information across Competition, and Coevolutionary the generations. That in turn makes Arms Races: Why Humans Evolved possible the reliable acquisition of Extraordinary Intelligence." complex, learning-dependent Evolution and Human Behavior 26: competences. 10-46.
The standard model captures important Gould, S. J. (1996c). Full House: The truths. Human decision-making does Spread of Excellence from Plato to depend in part on pre-wiring; on being Darwin. New York: Harmony Press. biologically prepared for certain challenges. And I have no doubt that the Gurven, M. and K. Hill (2006). Hunting as challenge of policing defection was one of Subsistence and Mating Effort? A the drivers of human cognitive evolution. Re-evaluation of "Man the Hunter", But it misses important truths. No model the Sexual Division of Labor and the
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Evolution of the Nuclear Family. Cambridge, Harvard University IUSSP Seminar on Male Life Press: 26-30. History. Giessen, Germany. Mesoudi, A., A. Whiten, et al. (2006). Gurven, M., H. Kaplan, et al. (2006). "Towards a Unified Science of "How Long Does It Take To Cultural Evolution." Behavioral and Become a Proficient Hunter? Brain Sciences 29 (4): 329-383. Implications For The Evolution of Extended Development and Long Mithen, S. (1996). The Prehistory of the Life Span." Journal of Human Mind. London: Phoenix Books. Evolution 51: 454-470. Hauser, M. (2006). Moral Minds: How Odling-Smee, J., K. Laland, et al. (2003). Nature Designed Our Universal Niche Construction: The Neglected Sense of Right and Wrong. New Process in Evolution. Princeton: York: HarperCollins. Princeton University Press.
Hull, D. (1986). "On Human Nature." Pinker, S. (1994). The Language Instinct: Proceedings of the Philosophy of How the Mind Creates Language. Science Association 1: 3-13. New York: William Morrow and Co. Humphrey, N. (1976). The Social Function of Intellect. Growing Pinker, S. (1997). How The Mind Works. Points in Ethology. P. P. G. Bateson New York: W.W. Norton. and R. A. Hinde. Cambridge: Cambridge University Press: 303- Pinker, S. (2007). The Stuff of Thought: 317. Language as a Window into Human Nature. New York: Penguin. Kaplan, H., K. Hill, et al. (2000). "A Theory of Human Life History Potts, R. (1998). "Variability Selection in Evolution: Diet, Intelligence and Hominid Evolution." Evolutionary Longevity." Evolutionary Anthropology 7(3): 81-96. Anthropology 9 (4): 156-185. Povinelli, D., et al. (2000). Folk Physics Klein, R. and B. Edgar (2002). The Dawn for Apes: The Chimpanzee's Theory of Human Culture. New York: of How The World Works. Oxford: Wiley. Oxford University Press.
Klein, R. G. (1999). The Human Career: Robson, A. and H. Kaplan (2003). "The Human Biological and Cultural Evolution of Human Life Origins. Chicago, University of Expectancy and Intelligence in Chicago Press. Hunter-Gatherer Economies." American Economic Review 93(1): Marlowe, F. (2007). "Hunting and 150-169. Gathering: The Human Sexual Division of Foraging Labor." Cross- Shennan, S. (2002). Genes, Memes and Cultural Research 41: 170-194. Human History: Darwinian Archaeology and Cultural Evolution. Marlowe, F. W. (2005). "Hunter-Gatherers London: Thames and Hudson. and Human Evolu-tion." Evolutionary Anthropology 14: 54- Skyrms, B. (1996). The Evolution of the 67. Social Contract. Cambridge, Cambridge University Press. Mayr, E. (1976b). Typological versus Population Thinking. Evolution and Skyrms, B. (2003). The Stag Hunt and the The Diversity of Life. E. Mayr. Evolution of Social Structure.
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Cambridge, Cambridge University Press.
Sperber, D., D. Premack, et al., Eds. (1995). Causal Cognition: A Multidisciplinary Approach. Oxford: Oxford University Press.
Sterelny, K. (2003). Thought in a Hostile World. New York: Blackwell.
Sterelny, K. (2006). "The Evolution and Evolvability of Culture." Mind and Language 21 (2): 137-165.
Sterelny, K. (2007). "Social Intelligence, Human Intelligence and Niche Construction." Proceedings of the Royal Society, London (series B) 362 (1480): 719-730.
Stiner, M. C. (2001). "Thirty Years on: The "Broad Spectrum Revolution" and Paleolithic Demography." Proceedings of the National Academy of Sciences 98 (13): 6993- 6996. Stiner, M. C. (2002). "Carnivory, Coevolution, and the Geographic Spread of the Genus Homo." Journal of Archaeological Research 10 (1): 1-63.
Stout, D. (2002). "Skill and Cognition in Stone Tool Production: An Ethnographic Case Study from Irian Jaya." Current Anthropology 43 (5): 693-722.
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much of the data on which nativist accounts rely can be accounted for without Kim Sterelny is an attributing a large number of genetically Australian philo- hardwire modules to the mind/brain. In sopher and profess-or 2008 Sterelny was awarded the Jean- of philosophy in the Nicod Prize.[4] His lectures are to be Research School of published under the title, The Fate of the Social Sciences at Third Chimpanzee. These lectures build Australian National on the non-Nativist Darwinian approach of University and Thought in a Hostile World, while Victoria University of providing a discussion of a great deal of Wellington. He is the winner of several recent work by other philosophers, international prizes in the philosophy of biological anthropologists and ecologists, science, and editor of Biology and gene-culture co-evolution theorists, and Philosophy. He is also a member of the evolutionary game theorists. After Australian Academy of the Humanities. studying philosophy at Sydney University, Sterelny's principle area of research is in Kim Sterelny taught philosophy in the philosophy of biology. He states "the Australia at Sydney, ANU (where he was development of evolutionary biology since Research Fellow, and then Senior 1858 is one of the great intellectual Research Fellow, in Philosophy at RSSS achievements of science.[1] Sterelny has from 1983 until 1987), and La Trobe also written extensively about the Universities, before taking up a position at philosophy of psychology. He is the author Victoria University in Wellington, where of many important papers in these he currently holds a Personal Chair in areas,[2] including widely anthologized Philosophy. He now spends half of each papers on group selection, meme theory year at Victoria University and the other and cultural evolution such as "Return of half of each year with the Philosophy the Gene" (with Philip Kitcher), "Memes Program at RSSS. Sterelny has been a Revisted" and "The Evolution and Visiting Professor at Simon Fraser Evolvability of Culture." Together with University in Canada, and at Cal Tech and his former student Paul Griffiths, in 1999, the University of Maryland, College Park, Sterelny published Sex and Death, a in the USA. He is Fellow of the Australian comprehensive treatment of problems and Academy of the Humanities. In addition to alternative positions in the philosophy of philosophy, Kim spends his time eating biology. This book incorporated a number curries, drinking red wine, bushwalking of the positions developed in previous and bird watching. articles on the range of topics in the philosophy of biology. At certain points Sterelny and his coauthor differed (for example, on the Darwinian treatment of emotions and on the prospects for developmental systems theory). In 2004 Sterelny's book Thought in a Hostile World: The Evolution of Human Cognition received the Lakatos Award[3] for a distinguished contribution to the philosophy of science. This book provides a Darwinian account of the nature and evolution of human cognitive capacities, and is an important alternative to nativist accounts familiar from evolutionary psychology. By combining an account of neural plasticity, group selection, and niche construction, Sterelny shows how
Human Natures 64
Dodos don't duck: Recent views on the life and demise of the dodo (Raphus cucullatus), in the context of natural selection
Michael Atchia
Past-president, IUBS-Commission for Biological Education, Botanical Garden, Melrose, Mauritius, [email protected]
Darwin’s theory of adaptation and natural selection perfectly explains the loss of flight ability of the Dodo living on this isolated island with no mammalian predators at all, as well as its subsequent extinction when confronted by powerful enemies with no evolutionary time to adapt.
Within less than 200 years (around the 17th century), the original forests of Mauritius were largely destroyed while garrison of colonial troops with little or no respect for nature in this foreign land plundered these birds for food or at times mere ”sport”. The introduction of rats, deer from Java, monkeys and pigs quite some time before the last dodo disappeared may have contributed to its demise.
Recent research on the Dodo aims at reconstructing the world of the dodo and determine the factors of its demise, at raising public awareness on the importance and vulnerability of island biodiversity and provide unique educational material for the study of evolution and the application of that concept to modern day living.
There's no way you will escape this year Since Darwin’s time, we have broadened the without hearing the name Charles Darwin scope of this fundamental concept. From again and again. 2009 is one of the most applying it only to organic evolution (“the significant anniversaries in science: it marks accumulation of inheritable changes within the 200th anniversary of the birth of Darwin animal and plant populations over time”) (12 February 1809), and the 150th we now refer to social evolution which is anniversary of the publication of his book “change in society and in human civilisation “On the Origin of Species by Means of itself” and to psycho-social evolution, that Natural Selection”. of the human mind. If a “revolution” is sudden, often violent change, “evolution” is gradual change, often Darwin slow, at time imperceptible, generally On February 12, 1809, two great men were occurring without direct human intervention. born: Abraham Lincoln, emancipator of It is a fact that some thinkers from ancient American Slavery and Charles Darwin, civilizations (e.g. ancient Chinese, Indians, emancipator of the human mind. Egyptians, Mesopotamians, Amerindians Darwin’s first claim to scientific fame was and others, but especially ancient Greeks) the great lengths he went to collect evidence had some idea that a process of gradual to support his hypotheses. Indeed he went change is in operation in the world and round the world painstakingly, not in 80 indeed in the Universe! days but full 5 years (from Dec.1831 to Oct Dodos don’t duck 64
1836) aboard the Beagle? Where did he go? Lessons From The Dodo Amongst others he went to Cape Verde “Flying is very expensive in terms of energy Islands, Rio de Janeiro, Patagonia, The and birds do not travel by air if it is safe for Falklands, Strait of Magellan, Galapagos them to do so by land” (David Attenborough Archipelago, Tahiti, Australia, New Zealand (1998). Which is why, during the course of and Mauritius, then back to England. history, several birds living in an area Darwin’s second claim to fame was his devoid of enemies and where food was ability to put all his observations together plentiful, abandoned the capacity for flight, and explain evolution by natural selection. for example ostriches, cassowaries, kiwis, ducks, turkeys and the Mauritian Dodo. For today, Darwin’s birthday week let’s Having become flightless and large, that stick largely to organic evolution and poor Dodo was a perfect example of being, examine the case of the DODO. Since the in survival terms island of Mauritius is about 13 million years • too fat, i.e. defenseless against old, volcanic in origin, it cannot have been predators, if and when they arrived, the ancestral location of birds, these being • too slow, compared to its cousin the much older on the evolutionary scale. Hence pigeon, the ancestors of the Dodo must necessarily • too “trusting” and relaxed vis-à-vis have flown here from some mainland, the these 17th century immigrants who likely origin being Madagascar and/or suddenly arrived by ship on its mainland Africa. Darwin’s theory of paradise island namely men, rats, adaptation and natural selection is fully pigs and dogs, applicable to explain why the ancestral • too isolated and unable to meet an dodo, living on this isolated island, with no era of “too fast” change! mammalian predators at all, lost its powers of flight and vastly increased in size! Why set up a Dodo Research Project Within less than 200 years (around the 17th (DRP)? The relatively recent date of human century) a minute time on the evolutionary colonisation of the island (1638) makes the scale, the original forests of Mauritius were demise of the Dodo a recent case of largely destroyed by garrisons of colonial extinction. Furthermore, the Mauritian troops with little or no interest in and respect historical and archaeological archives, for nature in this “foreign land”. They which contain a wealth of data on human plundered these birds for food or at times activities since colonization allow for mere “sport”. The introduction of rats, deer fundamental research on human impact in a from Java, monkeys and pigs quite some pristine natural volcanic island ecosystem. time before the last dodo disappeared may Specifically, the Dodo Research Project have contributed to its final demise. aims at reconstructing the world of the dodo Compared with other cases extinction (e.g. and determine the factors of its demise, at dinosaurs, mammoths, etc) that of the raising public awareness on the importance DODO was ultra rapid. Darwin’s theory and vulnerability of island biodiversity and equally accounts for its subsequent provide unique educational material for the extinction when confronted by powerful study of evolution (in particular, it is enemies with no evolutionary time to adapt. wished, an in-depth study of flight as a However, when Darwin came to Mauritius biological function) during his voyage round the world, the dodo had already disappeared and he does not Relevance of Evolution mention the Dodo by name, neither in his What can the study of evolution teach us “Voyage of the Beagle” (1845) nor in the about present day crises and problems? We “Origin of Species” (1859). have done the wrong things regarding the Dodo: for one these relatively uneducated
Biology International Vol. 47 65 Atchia
Dutch Sailors did not recognise the place of biodiversity and the right to exist of other living species. Which meant, in practice, Michael Atchia is they destroyed its habitat, and failed to Former Chief and exploit resources such as ebony and dodos Programme Director in a rational, sustainable way? We are with the United Nations tempted to say “never again”! But it almost (UNEP), co-responsible happened to the kestrel and pink pigeon and for the world-wide today it’s happening to some species of UNESCO-UNEP whales, while nearer to us the exploitation of International under- sized crustaceans in Madagascar is a Environmental sad example of economy choking ecology Education Programme from 1986 to 1996; a instead of the desirable sustainable co-ordinator and initiator of the first training “partnership” between the two! courses in integrated environmental management at Dresden, Adelaide, Geneva, From 12-15 Feb we are all here in New- Tufts in Boston, Nairobi etc. He is also the Zealand at the invitation of IUBS for this co-author of the world's first textbook on 200th anniversary of Darwin Conference, to Integrated EM ("Issues and Solutions" in examine the relevance of Darwin’s work to Environmental Management, John Wiley, today’s educational field. Also high level publishers, 1995). Apart from that, he is a discussions are continually taking place curriculum developer, radio and TV round the world to define sustainability in presenter; and is the first scientist from the practical, real-life terms, socially and South to be elected President of the politically acceptable. As one of the movers Commission for Education of IUBS. He was of such efforts, I strive to define what has to also Director of Education (Diocese of Port- be done now and in the next 30 years to save Louis, Mauritius) from 1997 to 2003; and a the ecological sustainability of this planet, Senior Adviser to Minister of Education, both at global level and nationally, for from 2004 to July 2005. example here in Mauritius through the “sustainable island project”.
However, the laws of evolution are drastic: words and no action have no effect, and the wrong actions have the wrong effects. It’s not easy to discern what to do now to ensure a sustainable future in 20 or 50 years time, let alone for the 22nd century! Those 17th century sailors who happily hit defenseless dodos on the head with sticks had no discernment. Are we better today? “Dodos don’t duck!” says Manning O'Brine in his detective story of 1953. Therefore “don’t be a dodo” be it in politics, in industry, in publishing, in schooling, or indeed in most walks of life, including religious practice!
Dodos don’t duck 66
Assisting Darwin Digitally
Guy Lévêque
University of Burgundy, France
I will present an example of use of software Level 1 for use in college. to address the concept of evolution in the The cognitive objective of the program is to classroom in middle school (11 years old understand the parameters used to classify pupils) and high school (last form 18). We living things according to a classification in will show the layout of the software and will an evolutive way rather than simply see how it can be used according to level of naturalist. The student assimilate the concept study and curricula. of shared feature. I will then submit a few thoughts from our research showing the role of digital literacy An instrument, like our software, for of students in their involvement in the example, includes two components: an learning of science knowledge. artifact, equipment and associated patterns Our question is: "How ICT tools can help of use that results from construction of the the student to assimilate certain elements of topic. During its use the software becomes a the theory of evolution proposed by Charles learning tool that allows the emergence of Darwin in the publication of the Origin of meaning by the student. There is therefore a Species in 1859?" first step, manipulation, a tool and a second time instrumentation that makes sense. Phylogeny software content and Pierre Rabardel (1999) called this process functionality. « instrumental genesis ».
Thus the student from a choice of living characters and their anatomical, morphological, physiological, embryological, builds a matrix of features (first use of the software, from data).
Picture1-Logiciel Phylogene
Phylogène contains data: pictures of animals, plants with Picture 2- Matrix of features information about their environment, their anatomic and physiological features It also contains data processing to built matrix to compare, Treatment with the software of these data and finally to draw enclosing boxes and phylogenetic tree. leads to a synthesis which display in
Biology International Vol. 47 67 Leveque colored, nested boxes, can give meaning and bring students to the notion of shared features (second use of the software: instrumentation).
Picture 3- Colored boxes « Russian dolls » Picture 5- Darwin’s tree (1837)
2 Level of use in high school. Species that share a common ancestor are The cognitive goal of the teacher is to closer, as suggested by Charles Darwin. impress upon students the formula for Thus the student reaches the a priori Darwin "descent with modification". In paradoxical conclusion that a sardine is terms of curriculum the aim is to take the closer to a mammal (cat) than to the shark concepts of ancestral character, and because it shares with the cat the same character derived from common ancestor. common ancestor that does not share with The student instrumentalises the software the shark (which is readable with the and the builds the array of characters. The construction of the graphical phylogenetic processing software allows a new tree). represental (different boxes), rich in meaning, the construction of a phylogenetic tree, as Darwin had drawn in 1837 of one of his notebooks. Processing software, instrumentation, is an aid to construction of the concept of the common ancestor.
Picture 6-Phylogenetic tree: cat and sardine closer
Conclusion
Picture 4- Phylogenetic tree from logiciel The software allows the student to highlight certain elements: a shared common ancestor, which will lead to the understanding of the theory of evolution. Given the multiple choice of parameters of the database the teacher can adjust its level of education and thanks to processing and display of the software get the student understand the cognitive notion. In the use of the object is a tool (handling the subject, choice of data) and instrumentation (for data processing)
Assisting Darwin Digitally 68 which arouses a sense in students. The To advance the use of ICT in schools, the student has an active part in learning. The next step is to develop software for the software is an educational tool suitable for a various types of learning in science. generation of students who instrumentalise Cooperation is needed between the with ease the software and adopt this type of designers of multimedia objects (engineers) media into the culture of science. We who are specialized in multimedia forms of develop this idea in our research laboratory expression and thus the "medial", and CIMEOS at the University of Burgundy teachers who are the scientific references of (France) "médié" (science content).
Reflexions from our research. Bibliography We show in our research, and by analogy to Bruner, J. (1996). The culture of Jerome Bruner1 "education allows entry into education. Harvard Univ. Press. the culture" and "digital culture of students L’Éducation, entrée dans la culture. the gateway to knowledge of science." Les problèmes de l’école à la lumière Students have acquired a digital culture in de la psychologie culturelle, Paris: their cultural habitus. Mark Prensky in a Retz. social classification refers to "Digital natives" for our students who have practiced Giordan, A. (1998). Apprendre. Paris: Belin. the use of ICT since childhood, as opposed to "digital migrants" for adults who have Giordan, A., Girault, Y., Eds, The new come to the use of ICT learning models, their consequences after their general education (books, for the teaching of biology, health and reading). environment, Nice: Z’ editions
For our part we establish a typology rather Jungck, J., Eds. (2002). The BioQUEST than social but cultural. We say that the Library. San Diego: Academic Press. student, by its digital culture acquired (often through the game, outside of school) is Prensky, M., (2008). La pédagogie aux “hypermédial”. In fact our research shows prises avec la Toile, Le Monde de that students, by analogy to the prompt l’éducatio. Avril 2008: numéro 368. action by the click of a mouse, easily read the signs of multimedia objects (image, text, and his associates on the same support). So, Guy Leveque defended his Docteurate at we speak of “hypermédial student”. This the University of Bourgogne in France in ease of reading instruments ICT encourages June 2009 on "La Culture Numérique, une the involvement of students in the entrance entrée dans les savoirs de science: Usages et to the knowledge of classical science in pratiques dans le monde éducatif." His school. mentors included André Giordan from the University of Geneva and Daniel Raichvarg In our research we analyzed the digital from the University of Bourgogne. He is object, CDs science in their classroom use. particularly interested in using interactive Our analysis shows that ICT tools include technologies to help students learn two elements that we call the "medial" and evolutionary concepts. He has many years of "médié." The medial is the multimedia experience in teaching at an innovative aesthetics of the image, script, dynamic university lab high school as well as at the sound input. The “médié” is mediated university level. science in instrument ICT.
1 Education in the culture Biology International Vol. 47 69 Leveque
Adapting teacher training to new evolution research approaches
François Edmond Lombard and Marie-Claude Blatter
TECFA, LDES, IUFE, SIB, ldes Université de Genève, Switzerland [email protected], [email protected]
As research methods have evolved to include new genomic approaches, based on freely available data and tools, an opportunity for proving and teaching evolution has been translated into teacher training programs in Geneva. The data from countless entire genomes and tools for comparing and extracting evolution evidence in conserved patterns, (BLAST, etc.) or building phylogenetic trees (Phylodendron,…) can be easily accessed via Internet. Ever more research in evolution is based on sequence analysis, providing new and very strong evidence. This authentic data and tools can be freely used by any student or teacher, opening new educational opportunities to explore, test and validate hypotheses. Possibly the strongest evidence ever is directly available to all schools. However new knowledge and competencies need to be developed to allow teachers to integrate these approaches into their classes. Indeed, these new information processing approaches in biology might be unfamiliar to biologists trained only a few years ago. As part of a comprehensive teacher training program in Geneva, evolution teaching and inquiry modules were developed within Geneva university in a collaboration of researchers in educational science LDES (Prof Giordan), TECFA and genomics (UniProtKB - Swiss-Prot,) and was deployed in teacher training programs since 5 years, and the scenario-based modules are freely available. How to include this new approach of evolution teaching in various chapters of biology, opportunities for new inquiry tracks for students will be discussed. Conditions and reasons for uneven acceptance of acceptance by institutions or teachers, and possible solutions will be discussed.
Evolution teaching is difficult cause species to evolve in certain ways?” “Nothing in biology makes sense except in (Wooley and Lin, 2005). The main questions the light of evolution (Dobzhansky, 1973) it in molecular biology research nowadays are is, however, a tricky topic for teaching as of the type “what are the underlying most learners come to it with previous mechanisms?” knowledge and it is fraught with misconceptions (Bishop & Anderson, 1990). Biology changes However, much literature And of course evolution teaching is a (Wooley and Lin, 2005 and National contentious issue (Skoog, 2005). Evolution Research Council, 2003) and our research is the chapter by which biology –up to then shows we are now seeing another paradigm mainly ontological and descriptive became change (Kuhn, 1972) in biology : towards explanatory. The questions that were “what information processing IT-Rich Biology, as is this species, this structure?” –moved Butler put it in a nutshell (Butler, 2001). towards conceptual questions “How did this “Are you ready for the revolution?” Our species appear? Why did this species acquire research has identified 4 aspects of IT- this particularity? What are the forces that
Adapting teacher training to new evolution research approaches 70 enhanced Biology that seem relevant to these “experimental approaches” are best education: thought of as we do for experimental, hands- • Bioinformatics, the application of on laboratory work. computers in biological sciences and especially storage and analysis of biological Should evolution teaching change? sequence data (DNA and proteins), and The field of research in evolution is also other experimental data such as 3D structure evolving with IT, but let’s just make it clear or microarrays, all the range of 'omics: this article is not about new teaching tools genomics, transciptomics, proteomics, etc. using IT (e.g. Sandoval & Reiser, 2003). In • Other biological databases such as contrast we suggest integrating IT-rich botanical zoological or georeferenced data biology in most chapters of biology (e.g. Google Earth). education with some of the data, the tools • Systems biology, synthetic biology and and methods used by today's evolution simulations. researchers. Moore says "Science teaching • Knowledge building in an infodense must evolve". He argues that "Many world: the ability to locate, use, and evaluate teachers are not scientifically capable of information (National Research Council, teaching evolution using modern 2000) “For life sciences ranging from approaches." (Moore, 2008) Our own ecology, botany, zoology, and research (Lombard, 2008) suggests that developmental biology to cellular and education is slow in recognizing this new molecular biology […] IT is essential to IT-Rich biology, and that new stimulating collect key information and organize opportunities for authentic learning have biological data in methodical ways in order arisen. Indeed Thomas Kuhn (Kuhn, 1972) to draw meaningful observations. Massive predicts that when a paradigm changes, as it computing power, novel modeling changes the fundamentals on which our approaches, new algorithms and professional identity relies, most mathematical or statistical techniques, and practitioners will resist the change. Many of systematic engineering approaches will us will remember how strongly the provide biologists with vital and essential expansion of biology to include molecular tools for managing the heterogeneity and approaches was resisted in schools and volume of the data and for extracting universities some 30-40 years ago. We will meaning from those data.” (Wooley and attempt to address in this article how to Lin, 2005). This new expansion of biology integrate new approaches to evolution in offers new way of experimenting, of curricula and classroom practices. building knowledge and of publishing science (Lombard, 2007). In fact informal Evolution teaching: new opportunities surveys have shown biologists spend more As our research suggests (Lombard, 2007) than half their time practising this IT-rich that the change of biology is widespread, biology. Most research published in high and affects most if not all aspects of impact magazines relies crucially of even evolution, it follows that there is no need to only on this sort of experimenting (Pollard, add a new chapter to biology, or evolution et al., 2006; Bakewell, et al., 2007; Gibbons, but that knowledge related to these new 2007). Massive new data and new tools offer approaches (fundamentals such as sequence opportunities to explore, test and validate coding, database organisation, concepts hypotheses, which define experimental such as alignment, underlying concepts such biology. We shall therefore speak of as parsimony principle for cladograms, etc.) experimenting for searching, comparing, and and competencies to manage this other explorations of the massive amounts of knowledge (how to extract a sequence, authentic data accessible in classrooms. health and evolution information related to a Some may recoil at this, but we would like gene, and similar sequences, how to to argue that in terms of learning potential, compare them ) are needed. Moore mentions
Biology International Vol. 47 71 Lombard and Blatter that "there is a big difference between mere (all the range of 'omics, but also systematic information and a teaching unit: teachers (e.g. UniProt Taxonomy), zoological and generally have no time or guidance to botanical (GBIF), biogeographic ecological elaborate new course units from raw etc ) and freely available tools such as materials." Rather than producing teaching BLAST, alignment (e.g. ClustalW), units, we would argue for training teachers Phylogenetic trees (Phylodendron), PhyML, to use real authentic tools available etc.) Our examples have been developed to everywhere via internet for free. Much integrate modern IT-Rich biology’s research (Schwartz, et al, 2004), authentic tools into most chapters of (Educational Researcher, 1990) point to the biology. Indeed paralleling the evolution of importance of authenticity "engagement in our science, we see, in accord with Moore inquiry activities similar to those of (Moore, 2008) but for the rest of biology scientists" (Schwartz, et al, 2004) too, an opportunity for science education to Authenticity goes three levels (Educational move closer to science. Researcher, 1990): A first level involves the facts: true research data is more authentic Opportunities for new inquiry tracks and than carefully selected, educationally strong evidence for Evolution polished data. A second level involves the The push to change of education towards tools and methods: involving students in more experimenting and inquiry strategies similar tasks, with the same tools and (Rocard, et al, 2006; NRC, 2000; NRC, methods as professional. A third level would 1996) is strong worldwide. And has involve students in "doing real research"; translated into lab and field opportunities for creating new knowledge. Quite a lot of learners to observe and experiment. One of research or standards (AAAS, 1993) the problems of evolution teaching is that encourages empowering learners to face typical courses offer limited opportunities real, complex problems rather than for experimenting. It is ironical that the oversimplify in an attempt to make learning field of evolution that brought biology out of easier (Jonassen, 2003): "The greatest a purely descriptive science into explanation intellectual sin that we educators commit is of causes (Wooley & Lin, 2005) has been so to oversimplify most ideas that we teach in resistant to experimental approaches in order to make them more easily education. Indeed, evolution changes often transmissible to learners. In addition to happen in a time frame incompatible with removing ideas from their natural contexts schools: over the course of millions of years for teaching, we also strip ideas of their - or within tiny invisible species such as contextual cues and information and distill bacteria. In both cases they remain rather the idea to their "simplest" form so that abstract to most students. Availability of students will more readily learn them. But authentic data and tools that can be freely what are they learning? That knowledge is used by any student or teacher, opens new divorced from reality, and that the world is a educational opportunities to explore, test and reliable and simple place. But the world is validate hypotheses. There are indeed not a reliable and simple place, and ideas simulations (e.g. MacEvolut one of us rely on the contexts they occur in for developed for simulating giraffe height meaning "(Jonassen, 2003) Consequently evolution) and semi-authentic data such as rather than developing new educational plastic models of skulls, bones and a few resources about this new IT-Rich biology, fossils are typically available in class. we set off to develop around existing Possibly the strongest evidence and authentic tools and data new teaching experimental exploration ever for evolution designs that might allow engaging student in - based on authentic research data - is now authentic activities at level 1 and 2. This is directly available to all schools. Evolution, possible because of the wide availability of or as Darwin put it "Descent with authentic biological data, through the web Modification" (Darwin & Carroll, 2003),
Adapting teacher training to new evolution research approaches 72 refers to common origin and evidence of implicit differences between meanings of gradual change, that can be related to same terms, data representation, knowledge environment. Vast amounts of sequences structure and priorities that are embodied in easily available offer strong opportunities to the databases etc. Indeed tools such as test common origin by exploring and BLAST, alignments, phylogenetic tree showing the universality of DNA, and building are not “just tools”: they are neither ‘quasi-universality’ of the genetic code transparent nor free of assumptions which Numerous proteins with similar function in influence the manner in which they can be different species (orthologs) are easy to find used (Rabardel, 1995) and induce change in and constitute strong evidence of common the strategies and their affordances need to origin. Aligning their sequences reveals be learned. This constant need for similarities and graduated differences, which mediation, translation structured the design: constitute evidence of progressive change. Two trainers embodied two poles of didactic Differences in function of transposition (Brousseau, 1998): a similar/homologous genes within a given bioinformatics specialist (M.-C. Blatter) in species (paralogs) reveals common origin the role of the expert bringing her scientific (gene duplication) and how random changes knowledge and a didactics specialist (F. can produce slightly different proteins can Lombard) playing the role of a naive be explored. Convergence of gene-function journalist asking questions to highlight can be discovered. crucial differences or possible misunderstandings. Similarly, for the A comprehensive teacher training participants, a lot of the training time was program in Geneva organized around dialoguing between All too often interactions between specialists of content (researchers) and universities and in-service teachers amount specialist of teaching (teachers). With time to a conference given by a specialist to very this interaction of researchers and teachers impressed teachers, who then go back to meeting halfway from the lab to classrooms school and teach as ever before. Although was pushed one step further: an expert these courses involved high profile presented how his field of biology is researchers of the Geneva university, the expanded by IT, how he imagined this course was designed so as to spend most of could/ should be imply changes in the time in interactions around how to education, and discussed with teachers how integrate this new knowledge into classroom and curriculum realities could classrooms, as this is known to be a key accommodate this. difficulty. Indeed the obstacles to information transfer (Huberman, 1986) Focused on scenarios effectively to teachers are known: such as Since teacher’s activity is mainly organized differing values, immediate usability, close around what happens in class, the design availability, etc. was built around scenarios embodying the knowledge into class-usable scenarios. The Synergy of scientific specialist and scenarios were designed to empower the education specialist participants to use authentic research data In a collaborative scheme involving the and tools. As it has often been observed that Geneva University (Swiss Institute of teachers need to modify, adapt and Bioinformatics (Swiss-Prot group), LDES personalize whatever teaching material they and TECFA) and Geneva High School use, the scenarios are open to customization. teacher training, we developed many In fact it has been shown that reusability is scenarios and trained teachers to integrate in great for the technical part of scenarios, but their teaching many of the new approaches minor for the pedagogical part (Pernin & that IT-rich Biology offers. We took time to Lejeune, 2004). Each step of the scenarios build a common language, and identified the is guided with detailed instruction and
Biology International Vol. 47 73 Lombard and Blatter comments. Links allow picking up the allowing to find genes and proteins from scenario at any point. All these scenarios their sequence (such as read from a gel), or are online and freely available on our web to find similar sequences o ClustalW (e.g) page for aligning them to show conserved regions http://tecfa.unige.ch/perso/lombardf/bist/. or prepare for trees o PhyML, Phylodendron Explicit place of insertion in the curriculum (e.g) for producing phylogenetic trees • was discussed. Most of the time one key use Develop a basic knowledge of the concepts of data and tools could be implemented in and terms. • Understand the logic of different chapters. E.g. finding the sequence organizing of theses databases which is of Insulin could be used while discussing the research–oriented and often differs from the physiology of glucose regulation or as an way teachers might expect the information example for biosynthesis of proteins or in to be structured: e.g. that RNAs are recorded evolution to establish the existence and as their cDNA sequences showing no similarities of such proteins in various Uracil, or that there are as many sequences species, and align them to form a for a protein as there have been researchers phylogenetic tree. Cross-opportunities to publishing about that sequence. • More establish the evolutionary evidence within generic information high-level literacy physiology, molecular biology or ecology competencies appeared as critical: being were highlighted. E.g. when searching for capable of teaching and learning efficiently human cytochrome in the context of cellular without understanding all the information respiration the fact that other similar offered: exhaustivity-resistance. Capacity to cytochromes from other species than ours synthesize from very different, fluctuating turned up could be incidentally highlighted. information sources, etc. Each scenario was explored by teachers during a course lasting 1-2 days offered to An example of scenario in-service secondary biology teachers. The One group of scenarios searches differences training involved a guided exploration of the in equivalent proteins (orthologs) and builds experimentation scenarios and the phylogenetic trees, which can be compared participants had time to explore and get with those built with other types of data: familiar with using the scenario and trying morphological and physiological characters to customize them, e.g. by using their for example. As an example we will favourite protein, or adapting them to their develop in some detail a representative specific teaching context with the help of the scenario: building a phylogenetic tree from trainers. The scenarios being available on- sequences of a given protein (insulin for line remain available for use in any school. example) in different species Like most The scenarios aimed at: • Develop a global other scenarios, we proposed 3 different view of the main databases and basic levels in terms of authenticity: 1) Basic understanding of their specificities, so as to level : Relies on a piece of on-line software be able to find nucleotide (Genbank, (PhyloPhylo) developed by the Swiss-Prot EntrezGene, etc) and protein group specifically for educational purposes: (UniProtKB/SwissProt, etc) sequences from It guides the learner along the key steps of a the names of genes and proteins, to be able phylogenetic sequence analysis: choice of to get research up-to-date information about the sequences from proteins for which genetic illnesses (Genes&Diseases), genes, sequences are available from many species, proteins. To find and visualize 3D structure comparison of these sequences (multiple of the proteins, or PubMed for articles. • alignment), building and visualization of the Have a basic familiarity with the crosslinks tree. Results are then discussed. By limiting and context indices so as to keep track and the steps and offering a minimum of options know enough to understand what is being this scenario reduces the risk of getting lost, viewed. • Develop a minimal familiarity and could helps focus on the main concepts. with the basic tools, such as o BLAST Doing so trades authenticity for simplicity of
Adapting teacher training to new evolution research approaches 74 use and offers teachers a reassuring linear adequate frequent updating media such as route by which students are guided. blogs or newsletters bridging research However, this might give the idea that the literature and educational practitioners. biological concepts explored are simple and We propose the following design rules: straightforward. 2) Medium level : This approach IT-rich biology as experimental scenario uses authentic databases lab work, empower students to use authentic (UniProKB) for selecting proteins from their data and tools whenever possible, design name, the on-line tools for aligning very precisely the technical part and loosely sequences and formatting (ClustalW), then suggest the pedagogical part of scenarios. uses a simplified research tool (Phylodendron) for producing and References visualizing the tree. As such this scenario is more complex but more authentic, giving Dobzhansky, T. (1973). “Nothing in biology students a glimpse into the richness of data makes sense except in the light of available but guiding them enough to evolution.” American Biology Teacher produce meaningful results. As for any 35 (3): 125-129. hands-on lab activity, the guidance and perspective the teacher gives is crucial to Bishop, B.A. and C.W. Anderson. (1990). help students build real knowledge and not “Student conceptions of natural only go through the motions, in what selection and its role in evolution.” Bereiter calls “reduction to activity” Journal of Research in Science (Bereiter, 2002). (Scenario 5) 3) Advanced Teaching 27 (5): 415-427. level: this scenario uses the tools available on the web as researchers in their lab Skoog, G. (2005). “The Coverage of Human (Scenario 5pro). This scenario differs mainly Evolution in High School Biology in that it explores into more depth the Textbooks in the 20th Century and in options of how the same alignment can often Current State Science Standards.” lead to slightly different trees depending on Science & Education 14 (3 - 5): 395- the assumptions made. And allows students 422. to develop perspective on the assumptions implicit in building trees. These scenarios Wooley, J.C. and H.S. Lin, (2005). have been integrated to some degree or other “Catalyzing Inquiry at the Interface of in many secondary and high schools in Computing and Biology.” Committee Geneva. on Frontiers at the Interface of Computing and Biology, National Conclusion Research Council, in Committee on We believe the time is ripe for integrating Frontiers at the Interface of IT-rich evolution into classrooms, and that Computing and Biology, National this needs proper teacher training. We Research Council. (J.C. Wooley and suggest explicitly addressing the fact H.S. Lin, Eds.). National Academies biology is changing, in particular by having Press. recognized biology researches describe how IT plays into their work. We suggest that a (2003). NRC Committee on Undergraduate design based on the confrontation of biology Biology Education to Prepare experts (researchers) and experts in Research Scientists for the 21st education around scenarios can be very Century, BIO2010: Transforming fruitful. We suggest this includes helping Undergraduate Education for Future teachers develop information literacy Research Biologists. National strategies to avoid information overload, Research Council. which should be thought of as a long-term training effort, which could be supported by
Biology International Vol. 47 75 Lombard and Blatter Kuhn, T. (1972). La structure des bridging the gap between nature of révolutions scientifiques. Paris: science and scientific inquiry.” Flammarion. Science Education 88 (4): 610-645.
Butler, D. (2001). “Are you ready for the (1990). The Cognition and Technology revolution?” Nature 409: 758-760. Group at Vanderbilt, Anchored Instruction and Its Relationship to Lombard, F. (2007). “L’actualité de la Situated Cognition. Educational biologie : vulgariser ou autonomiser?” Researcher. 19 (6): 2-10. in JIES : XVIIIes Journées internationales sur la communication, (1993). AAAS, Project 2061, Benchmarks l'éducation , la culture scientifiques for Science. American Association for techniques, et industrielles. the Advancement of Science: Chamonix. Washington.
Pollard, K.S., et al., (2006). “An RNA gene Jonassen, D.H. (2003). Learning to Solve expressed during cortical development Problems with Technology: A evolved rapidly in humans.” Nature Constructivist Perspective. Upper 443 (7108): 167-172. Saddle River NJ. Merrill Prentice Hall: USA. Bakewell, M.A., P. Shi, and J. Zhang. (2007). “More genes underwent Rocard, M., et al. (2006). “Science positive selection in chimpanzee education Now : a renewed pedagoy evolution than in human evolution.” for the future of Europe” in PNAS 104 (18): 7489-7494. Directorate-General for Research (M. Rocard, Ed.) OECD EUROPEAN Gibbons, A., (2007). “Human Evolution Is COMMISSION Bruxelles. Speeding Up.” Science ScienceNOW Daily News (10December 2007). (2000). NRC National Research Council, Inquiry and the National Science Sandoval, W.A. and B.J. Reiser, (2003). Education Standards. A Guide for “Explanation-Driven Inquiry: Teaching and Learning. Centre for Integrating Conceptual and Epistemic Science, Mathematics, and Scaffolds for Scientific Inquiry.” Engineering Education, ed. Science Education 88 (3): 345-372. C.o.D.o.a.A.t.t.N.S.E.S.o.S. Inquiry. National Academies Press. Moore, A., “Science teaching must evolve.” Nature 453 (7191): 31-32. (1996). NRC, National science education standards. Washington, DC: National Lombard, F. (2008). “Information Academy Press. Technology (IT) to change biology teaching, or teaching IT-changed Darwin, C. and J. Carroll. (2003). On the biology?” in BioEd 2008, Biological Origin of Species. Broadview Press. Sciences Ethics and Education The Challenges of Sustainable Huberman, M. (1986). “Répertoires, recettes Development. Dijon. et vie de classe : comment les enseignants utilisent les Schwartz, R.S., N.G. Lederman, and B.A. informations.” in L’art et la science de Crawford. (2004). “Developing views l’enseignement. (M. Crahay and L. D., of nature of science in an authentic Eds.) De Boeck: Bruxelles. 151- 185. context: An explicit approach to
Adapting teacher training to new evolution research approaches 76
Rabardel, P. (1995). Les hommes et les François Lombard has technologies, approche cognitive des been Involved since 1980 instruments contemporains. Paris: in biology education as a Armand Colin. teacher, an educational software developer, a Brousseau, G. (1998). Théorie des situations teacher trainer and since didactiques. Grenoble: La pensée 1999 he is a lecturer and sauvage. a researcher at Geneva University. There he has been in charge of a pre-service Pernin, J. P. and A. Lejeune. (2004). teacher training course in integration of Dispositifs d'apprentissage Information Technology to support instrumentés par les technologies : education. He now teaches biology vers une ingénierie centrée sur les diodactics for pre-service biology teachers scénarios. Technologies de at IUFE in Geneva university. l'Information et de la Connaissance dans l'Enseignement Supérieur et de His research has been focused on the use l'Industrie. Compiègne: Université de of technology in education, in particular Technologie de Compiègne. 407-414. computer supported science knowledge building. Bereiter, C., (2002). Education and Mind in He now explores designs to integrate the the Knowledge Age. Second ed.: deep changes biology is undergoing Lawrence Erlbaum Associates. (information technology-rich biology such as bioinformatics, genomics, systems biology, etc. ) in school practice. After a PHD in Biochemistry at the Geneva University, Marie-Claude Blatter has worked as post- doc at the Geneva Hospital where she studied the genetic and environmental risk factors for cardiovascular diseases. She joined the Swiss-Prot team of the SIB Swiss Institute of Bioinformatics in 1997. She specializes in mammalian protein annotation for the UniProt protein knowledgebase. As head of the Swiss-Prot communication team, she is also involved in education and training activities (University of Geneva, hands-on bioinformatics training in Switzerland and Europe) and communication with the public at large.
Biology International Vol. 47 77 Lombard and Blatter
Project MUSE: Involving High School Students in Evolutionary Biology through Realistic Pr oblems and Causal Models
Jim Stewart1, Cindy Passmore2, Jennifer Cartier3
1Professor of Science Education, Department of Curriculum & Instruction, University of Wisconsin-Madison, Madison, Wisconsin 53706, [email protected] 2Associate Professor, School of Education, University of California – Davis, One Shields Avenue, Davis, California 95616, [email protected] 3 School of Education, University of Pittsburgh, 5523 Wesley W. Posvar Hall, Pittsburgh, PA 15260, [email protected]
The Modeling for Understanding in Science Education (MUSE) project is one in which high school science teachers and their students at Wisconsin's Monona Grove High School, and science educators from the University of Wisconsin-Madison, have collaborated for over a decade to improve teaching, student learning, and student reasoning in a variety of scientific disciplines. Currently, the project involves an extended unit in earth-moon-sun dynamics taught as part of the ninth grade science course, extended units in genetics and evolutionary biology that are taught in the tenth grade course (these two courses are taken by all students in the school), as well as two elective nine-week courses in genetics and evolutionary biology that are a part of the school's innovative, elective science offerings for students during their senior year. The heart of the MUSE project includes research on learning and reasoning, development of instructional materials, and professional development. Teachers who make a commitment to having classrooms function as scientific communities work to realize that it is a long- term commitment, one that requires careful planning and orchestration. Five such significant activities include: Using models to pose research questions; Developing explanations that link causal models and data; Revising causal models in light of anomalous data; Assessing the adequacy of explanations, and revising them as necessary; and, Considering what reasoning patterns they have used when conducting inquiries. Through observation, we identified three different types of evolutionary problem solving: Model-less problem solving; Model-using problem solving; and, Model-revising problem solving. Students in this course were able to reason and argue from data, develop their own explanations for natural phenomena, and evaluate the hypotheses of their peers—in sharp contrast to students in traditional courses who often leave with a memorized list of facts and an “understanding” of evolution as a belief system rather than as a reasonable scientific explanation of phenomena and species change.
Introduction (http://ncisla.wceruw.org/muse/; Cartier & For more than two decades members of Stewart, 2000; Stewart, Cartier & Passmore, Project MUSE (Modeling for Understanding 2005; Stewart, Cartier, Passmore, Rudolph, in Science Education) have developed & Donovan, 2005; Cartier, Stewart, curricula to engage students in realistic Passmore, & Willauer, 2005). In addition, inquiries in genetics, evolutionary biology, MUSE classrooms have served as the site of astronomy and kinetic molecular theory research on student understanding, problem
Project MUSE 78 solving and reasoning (Cartier & Stewart characters were shown participating in 2000; Cartier & Stewart; Johnson & unanticipated actions and events. Stewart, 2002). Although the primary goal of the cartoon The MUSE High School Evolution Course activity was to provide a context in which It is important for students to understand key students could engage in historical reasoning knowledge claims in evolution and the and construct narrative explanations, it also means by which evolutionary biologists allowed them to analyze the structure of generate and justify those claims. To help scientific arguments. Discussions about the students develop such knowledge, we story differences provided opportunities to created opportunities for them to participate consider how individuals’ prior knowledge in activities that parallel two types of and beliefs, as well as their observations and evolution inquiry—establishing the interpretation of the cards, led to a range of chronology of the history of life on Earth inferences related to story sequences. and using causal models, primarily natural Following this activity, students turned their selection, to explain patterns found in the attentions to three distinct explanations for historical record. The course was organized species diversity and adaptation to local into four sections: circumstances. • Introduction to the relationship between prior knowledge, data, and Comparison of Three Models inferences in the context of learning In this section, students read excerpts from about the nature of historical the writing of Paley, Lamarck and Darwin reasoning. that spoke directly to the authors’ views on • Comparison of three models that the reasons why organisms seem so well purport to explain the diversity of adapted to their circumstances. Students also species. experienced phenomena that inspired each • Development of Darwin’s natural author’s model—they examined fossils selection model. discussed by Lamarck, dissected an eye to • Investigative cases that allow observe the structure and function students to use and revise the natural relationships that so intrigued Paley, and selection model. were visited by a pigeon breeder who brought with her several of the pigeon Prior Knowledge, Data, Inferences, and breeds described by Darwin in Origin of the Historical Reasoning Species. The students returned repeatedly to This section of the course provided students the argument analysis structure developed with a common language and the analytical during the cartoon activity. tools with which to examine and critique evolutionary explanations and arguments. Once students understood each author’s The section began with an activity that proposed mechanism for species diversity served to introduce historical reasoning. In it and the observations on which each was students were given 13 images from a based, they worked to identify the cartoon story (depicting characters from assumptions underlying each argument. The Little Red Riding Hood and The Three Little first set of assumptions concerned the Pigs) and asked to sequence the images as authors’ view of species—was it fixed or the first step in constructing a narrative to malleable, and what role was attributed to share with their classmates. The cartoon variation within species? The second set activity was created using familiar concerned the author’s view of the “force” characters so that students could rely on responsible for the development of new background information to form their species. Next, students compared the three inferences about the story. However, the models. They evaluated the explanatory power of each by attempting to use each one
Biology International Vol. 47 79 Stewart, Passmore, and Cartier to explain phenomena other than those (e) An acknowledgement that the described in each author’s original paper. occurrence of the trait has changed in the population. Finally, students compared and critiqued the authors’ underlying assumptions. This Students first explored variability in allowed them to recognize that it is good sunflower seeds and then in Wisconsin Fast practice to question the central assumptions Plants™. The sunflower activity introduced of a model—even if the model seems to students to the powerful ideas that (a) all explain phenomena. Comparing assumptions individuals of a species vary and that (b) for of the three models enabled students to most traits there is a wide range of variation distinguish those beliefs that underlie the rather than the two-character state model of natural selection (a natural encountered in typical genetics instruction. mechanism acting on variation within The students then considered variability in populations) from those that underlie populations of Wisconsin Fast Plants™ that Paley’s model (supernatural influence) and they had grown. Lamarck’s (individual need). By parsing the arguments into the data, prior The final activity of this unit extended knowledge and beliefs, and inferences previous work with Fast Plants™ in order to drawn, students were able to make examine the results of artificial selection and comparisons across all three models. This to consider ways to represent distributions both supported a deeper understanding of before and after selection events. Once the models themselves and provided clear students had developed an understanding of dimensions along which to compare them. the natural selection model, they then used it Students came away with an understanding to reason about realistic data in the form of of why biologists accept Darwin’s natural investigative cases. selection model. Using and Extending Darwin’s Model Developing the Natural Selection Model Once familiar with the natural selection Even though students had been introduced to model, students developed a Darwinian Darwin’s model of natural selection, its explanation for a simple adaptation scenario details needed elaboration. The details that prior to experiencing more complex were provided to students about the model’s situations in the form of the following structure paralleled the content in most high investigative cases. school biology textbooks. The major differences were the systematic way it was Seed case. This case was based on developed and the emphasis on its role in hypothetical organisms for which a large creating Darwinian explanations to account amount of data was supplied. The for changes in populations in terms of: phenomenon to be explained was the change (a) A description of variability in a trait in seed-coat characteristics in populations of within the population at some past a hypothetical plant. Students were given time, descriptions of the ancestral population, (b) A reference to the variability in the natural history information on contemporary population, populations, predation information, and data (c) A discussion of the heritability of that allowed them to establish the trait’s the trait, heritability. (d) A description of the selective advantage of the trait and an The students worked in groups, using the explanation for how that advantage natural selection model to explain the led to improved chances for survival change in either seed-coat thickness or and reproduction, and number of seed-coat spines over time. Students were expected to develop an
Project MUSE 80 explanation using the natural selection and population densities of monarchs and model as well as to connect data from the viceroys in a meadow. A range map showed case materials to each component of the that the distributions of the monarchs and model. The case ended with a poster session viceroys overlapped and that there were during which students presented their larger numbers of monarchs than viceroys in posters and critiqued each other’s this area. explanations. The focus on population density data was Viceroy–monarch and pheasant cases. useful to some students in imagining how Unlike the seed case, these two cases were predators would begin to associate bad taste based on actual organisms and included less with bright coloration. They were concerned information (e.g., no description of an with the apparent disadvantage of bright ancestral population). Working with the coloration in terms of individual monarch cases allowed students to extend their predation by birds that had not yet learned to understanding of the applicability of natural avoid monarchs, yet they could imagine how selection by constructing explanations for genes for bright coloration could be situations in which the selective advantage advantageous in the population as a whole was not immediately clear—the similarity in if, on average, the predators started to color between viceroy and monarch associate brightness with distastefulness. butterflies and sexual dimorphism in ring- necked pheasants. Applying natural Students also incorporated issues of species selection to these cases required a rich interaction when they recognized the understanding of the model and the potential problem for the monarchs if there assumptions upon which it is based. This were more harmless viceroy mimics: portion of the course provided students with “They’d just keep eating them” (the brightly opportunities to work in groups, compare colored butterflies) if it were “the other way explanations among the groups, and present around” (if there were more harmless than preliminary ideas. The culminating activities harmful butterflies). This appreciation for were a roundtable discussion for the the complexity of species interaction in monarch-viceroy case and a research- evolutionary terms indicated a high degree funding competition for the pheasant case. of understanding of explanations for evolutionary phenomena using the Monarch–viceroy case. The students were Darwinian model. provided with diverse data with which to develop a Darwinian explanation to account Pheasant case. Organized as a research for the similarity in appearance between the funding competition, students developed a two species. After creating their Darwinian explanation for the bright explanations, students read and critiqued coloration of male ring-necked pheasants that of another group before meeting as a and supported it with evidence available in class to discuss their arguments and provide case materials. Once they devised an data to support their claims. explanation students prepared a research proposal to follow up on some aspect of Students differed in the data they used to their explanation. Research teams then support how this advantage might have presented their explanations and research originated. As the discussion progressed and questions to compete for funding while other students addressed the types of data that groups acted as proposal reviewers. Students different groups brought to bear, the demonstrated understanding through interactions became more sophisticated as reviewers’ questions and critiques and not everyone assigned equal importance to presenters’ responses to this feedback. certain pieces of data. For example, the case contained information on the habitat, range,
Biology International Vol. 47 81 Stewart, Passmore, and Cartier With one exception, all of the student coloration, and sexual selection to students Darwinian explanations for the bright as concepts to be memorized, here students coloration of male pheasants were consistent had to grapple with phenomena and create with sexual selection, even though there had plausible and well supported explanations. not been any instruction on sexual selection. Doing so allowed them to increase their With each of the research questions understanding of the explanatory power of proposed, the students attempted to establish evolution generally and natural selection the selective advantage of the trait and to specifically. devise ways to test their hypotheses. Three groups proposed exploring the role of Our High School Evolution Class in the female choice in conferring a reproductive Overall Context of Project MUSE advantage to brightly colored male Our goal has been to help students develop pheasants. Another group proposed understanding by introducing them to investigating the possible link between aspects of what is involved in thinking bright coloration and other advantageous scientifically while simultaneously traits, such as increased fertility or immunity providing them with experiences that have to disease. A fifth group wanted to establish some fidelity to the work of scientists. We the timing for acquiring bright plumage, chose to emphasize the concepts of inquiry, reasoning that their hypothesis that bright scientific practice, causal model, coloration aided in courtship would be explanation, and argumentation. Following supported if they could establish a an overview of inquiry we will develop the correlation between timing of sexual ideas of scientific practice, causal model, maturity and development of bright explanation and argumentation. plumage. They believed that the disadvantage of bright coloration in terms of Scientific Inquiry predation could only be outweighed if the School science should introduce all students development of bright plumage coincided to the frameworks and "habits of mind" by with the mating season, thereby providing a which scientific knowledge is created. reproductive advantage. As in the discussion However, students often identify surrounding the monarch–viceroy case, experimentation as the hallmark of scientific students interacted in sophisticated ways inquiry; the yardstick by which an activity is while defending their research proposals. gauged as being truly scientific or merely an imposter. By equating scientific inquiry with In the pheasant case, students used an experimentation students' attention is drawn established phylogeny to support their to its procedures (e.g., controlling variables, claims about the ways pheasants might have making observations etc.) with the result changed over time. They used this that they fail to appreciate the rich information on closely related species in conceptual contexts within which order to determine a likely scenario for the experimentation occurs. way the ancestral population might have had slight differences between the sexes. The In addition, by focusing on the mechanics of use of this phylogenetic information experimental design students fail to illustrated one way in which students used appreciate that experimentation is but one of historical reasoning to create explanations a diversity of approaches used by scientists for natural phenomena. to conduct empirical inquiries. An understanding of the diversity of ways by Students’ explanations for the case which scientists generate justified claims phenomena required that they extend their can begin to emerge when students become knowledge of the Darwinian model. In conversant with the major conceptual and contrast to traditional evolution instruction, methodological structures of the science which often presents mimicry, warning being studied. We have found that it is
Project MUSE 82 possible for students to understand that the • What standards are used to assess provinces of various sciences as unique and the claims made by the members of yet, at the same time, recognize that there a practice? are important commonalities that underlie all sciences. Causal Models Scientific understanding results as students Scientific Practice create explanations that join the empirical If scientists conduct inquiries of diverse and theoretical worlds. Central to this view types to develop understanding of the world of understanding and explanation is the then there is value in looking to how they concept of causal model (a set of ideas that organize themselves to conduct such describes a natural process, and, given inquiries. We have found Kitcher’s (1984; certain constraints, can be used, by scientists 1993) concept of scientific practice useful or students, to explain or predict when developing curricula that invite phenomena). In evolution, natural selection students to go beyond an oversimplified is such a model as, like any scientific model, view of science. Kitcher acknowledges the it influences and constrains the questions educational utility of considering a scientists ask, the evidence they seek, and discipline in terms of its practice when he the claims that they are willing to make. asserted that for students to understand a The significance of causal models to science they must: scientific practices is that they serve as the …know what questions are to be asked primary mediating conceptual elements about hitherto unstudied examples, between the scientific community and the …know how to apply the technical natural world. It is not possible to consider a language to the organisms [Kitcher was scientific problem independent of some writing about genetics] involved in these model. However, models do more than serve examples, and …can apply the patterns as templates for the conduct of empirical of reasoning which are to be instantiated research because a model may become the in constructing answers. More simply, focus of inquiry when it is thought to be successful students grasp general inconsistent with empirical data, have patterns of reasoning which they can use internal inconsistencies, or be inconsistent to resolve new cases (p. 354). with other established models. When concern with a model arises the inquiry of We have found that the following questions, the scientific community, or some of its derived from an understanding of scientific members, turns from the application of practice to be useful when framing models to solve empirical problems to the discussions about student learning and exploration of conceptual inconsistencies curriculum development: and their implications (Laudan, 1977). • What causal models underlie the Curricula that involve students in scientific science discipline to be taught? practices should provide them with • What language is central to opportunities to explore a diverse range of understanding and using those scientific problems. models? • What statements about the world do Scientific Explanation members of the practice accept? Salmon (1998) wrote “… explanation is a • What reasoning patterns do central, if not the central, goal of scientific scientists use when conducting endeavor” (p. 80, emphasis in original). We inquiries? feel that it is through the act of constructing • What problems does the discipline explanations that students, like scientists, agree are in need of solution? develop understanding. It is this intimate connection between explanation and understanding (it might be said that
Biology International Vol. 47 83 Stewart, Passmore, and Cartier understanding is contingent in large part on it provided a means of unifying what, to pre- one’s ability to explain) that is of interest to Darwinian biologists, appeared to be very us. different, but biological intriguing, problems in biogeography, embryology, classification, Our concern with explanation is, in part, morphology, and paleontology. Following related to the posing and answering of WHY Darwin, each of these areas was seen to be questions for singular events or for patterns addressable using a descent with in events. Such questions seek answers in modification framework and the explanatory the form of explanations that propose a structure of a Darwinian history (Kitcher, causal mechanism (a model) to account for 1994). Given its central position in science, the data in question. This common explanation should also be prevalent in explanatory form involves the intersection science instruction. of some causal model, or models, with data (Pickett, Kolasa, & Jones, 1994). Scientific Argumentation For us classroom argumentation is the public However, there is a second conception of face of the activities of inquiry, modeling, explanation—one that emphasizes the and explaining. These intellectual activities unification of seemingly unrelated conducted within a scientific practice, and phenomena (Kitcher, 1993; Salmon, around which one might expect high school 1998)—that also deserves inclusion in students to engage in argumentation include science instruction. This sense of • Using models to pose research explanation, demonstrating that apparently questions, disparate phenomena or even explanatory • developing explanations that link models can be seen as fundamentally causal models and data, similar, is central to science. • revising causal models in light of anomalous data, One such type of unifying explanation can • assessing the adequacy of be illustrated with an example from explanations, and revising them as evolution that illustrates unification of necessary, seemingly unrelated phenomena. • considering what reasoning patterns Phylogentic trees from diverse groups of they have used when conducting organisms may appear quite similar to inquiries students and yet, it may not be obvious to them to consider accounting for the The focus of the following discussion is similarities with common underlying causal limited to the connections between models. But this is just what is allowed by argumentation and explanation. coupling Darwin’s natural selection model with a model of speciation involving Argumentation is not only a culminating geographic isolation. One result of this activity, one that occurs at the end of an unification is that students perceive inquiry, nor does its public nature require evolution as something other than a grab bag large groups. Argumentation can occur of unrelated models to be memorized (e.g. between two individuals (as a continuation selection, mutation, migration, drift, descent of dialogues that an investigator has with with modification). herself) and it occurs continually throughout an inquiry. When focusing on an A second sense of explanation as unification explanation as a part of argumentation there can also be illustrated with an example from is a concern that the explanation does not evolutionary biology. It is widely violate the assumptions of the model that is acknowledged that the power of Darwin’s used in its construction and that it actually On the Origin of Species by Means of Natural Selection was the manner in which
Project MUSE 84 does account for the phenomena/data at provide students with a mode of inheritance hand. (a cause) and ask them to provide phenotype and genotype ratios (the effect) that would Teachers who make a commitment to having result from a cross between two parents with classrooms function as scientific known genotypes whereas those solved by communities need to realize that it is a long- geneticists involve reasoning from effects term commitment, one that requires careful (phenotype data) to causes (inheritance planning and orchestration. A classroom patterns) that might account for the observed where argumentation is taken seriously effects. When discussing cause-to-effect and involves more than students making effect-to-cause reasoning / problem solving presentations where there is but perfunctory within the context of our instruction and discussion. Those making presentations, and research it is easy to do so in genetics as the it may be to one or two other students students were, as the course progressed, working in a ‘research group’, involves a working with multiple models. The students deft coordination of data and models in a were not given a single model to use (such way that others can follow the flow of the as simple dominance); rather they had a explanatory argument. Similarly, those diversity of models at their disposal and students who are being persuaded have a generated data (using BioQUEST’s Genetics significant role to play. They have to attend Construction Kit). Their challenge was to to the explanation, have to be aware of the map the data to a model that best explained standards for assessing explanations and it. Because students had the ability to have to be inclined to use those standards as generate realistic data the reasoning that was they interact with others. expected of them was quite different from that expected of students in standard high Classroom Experiences school instruction. The development of MUSE instructional materials was also shaped by our research While the distinction between the two types on student learning, reasoning and problem of reasoning also applies in evolution it was solving. Initially, our research was focused less a central part of our course as our on genetics and was conducted in primary concern was with providing classrooms where we were not involved in students opportunities to develop and use the the instruction. We then began to develop natural selection model to interact with what we felt were more intellectually realistic data as they constructed Darwinian engaging instructional materials for explanations. By the time students began students, ones in which their activities were working on the investigative cases they were more consistent with those of scientists— using but a single model, natural selection, particularly the nature of the problems to construct explanations. While they had to solved. deal with diverse types of realistic data they were in a different situation then when As we made this transition we realized that solving genetics problems that required the problems students were being asked to effect-to-cause reasoning. solve required very different reasoning patterns than those scientists confronted. It is easy to imagine situations in evolution This led us to distinguish between problems instruction that would require students to that required reasoning from known causes engage in effect-to-cause reasoning—for (generally models) to effects (data) and example when analyzing data using both more realistic problems that required allopatric and sympatric models of students to reason from effects to causes. In speciation. However, this is not something the context of MUSE it is easiest to illustrate that we expected of students do in our the above with an example from genetics. course. Textbook genetics ‘problems’ typically
Biology International Vol. 47 85 Stewart, Passmore, and Cartier Because of our experience with the genetics the model. In our evolution course this course it became evident that students could occurred when students had developed such engage with sophisticated problem contexts, an understanding of Darwin’s model of ones that allowed them to develop natural selection, its components and its significant conceptual understanding, value in making sense out of changes in reasoning abilities and insights into the populations. The students used this model as natures of scientific practice. We then they interacted with the data in each of the further differentiated problem-solving three investigative cases in order to develop reasoning into four categories: model-less, Darwinian explanations. The use of a model model-using, model-elaborating, and model- gives students great power as it can be revising. These categories were instrumental applied outside of the examples that were as we developed our genetics and then our used in its development—it functions as a evolution instruction. conceptual goggles for looking at and making sense of the world. Natural selection Model-less problem solving is a powerful intellectual tool for the student Model-less problem solving occurs when the of evolution. primary method of solving problems involves the use of algorithms (rules that if Model-elaborating problem solving applied properly and in the right sequence, Model-elaborating problem solving occurs will guarantee a correct answer). By using when the primary motivation for solving algorithms it is often possible to obtain the problems is to come to new understandings. expected answer to a problem without Although still bound by the concept of an actually understanding the biological existing model, there is interesting reasoning concepts involved. In genetics it is possible occurs, and new insights may emerge, from to be adept at solving many textbook solving problems in which the data does not problems using a Punnett Square algorithm conflict with existing models. These may without realizing its use implies independent lead students to: assortment, segregation or fertilization. In • Learn more efficient procedures for evolution we have seen many students who generating data. are perfectly capable of carrying out all of • Develop within-model conceptual the calculations associated with Hardy- insights. In genetics, one elaboration Weinberg problems—they are algebraically of the model, multiple alleles, is the adept. However, they do not recognize that recognition that the number of Hardy-Weinberg is, like Newton’s variations for a trait is a function of frictionless universe, an ideal state; a the number of alleles in the baseline against which to measure changes population and the types of in populations. They treat the Hardy- interactions (simple dominant or Weinberg formula as a tool for solving codominant) among pairs of alleles. problems and not as a powerful model to In evolution, students begin to gauge the extent of changes in gene realize that the natural selection frequency and then as a basis for model is not limited to accounting considering what factors might have caused for the rise of novel structural those shifts in gene frequency. characteristics but that it is equally useful for making sense out of Model-using problem solving behaviors as well. Model-using problems solving occurs when • Link models because they share a causal model is used to solve problems for object, processes or states. For which the model is appropriate. Engaging in example, linking mutation and model-using problems solving requires the selection with descent with use of heuristics that are embedded in a deep modification. understanding of the conceptual nature of
Project MUSE 86
• Linking models to produce a larger traditional courses who often leave with a framework (e.g. natural selection, memorized list of facts and an models of speciation and genetic “understanding” of evolution as a belief models). system rather than as a reasonable scientific explanation of phenomena and species Model-revising problem solving change. It may be that the real problem is to revise an existing model to fit anomalous data. In References this latter case they may both learn new conceptual and procedural knowledge, and Cartier, J. & J. Stewart. (2000). “Teaching develop understanding of how science is the nature of inquiry: Further conducted. The need to revise a model developments in a high school comes about when a lover recognizes that genetics curriculum.” Science & the empirical world fails to fit completely Education. 9: 247-267. any models that formerly have facilitated description, explanation, and prediction. Cartier, J., Stewart, J., Passmore, C. & Because people use models to focus their Willauer, J. (2005). “Involving expectations about how the world works and Students in Realistic Scientific thus what observations to expect, it permits Practice: Strategies for Laying them to recognize anomalies. Students in Epistemological Groundwork.” In our evolution course did just this when, in Everyday Matters in Science and the Pheasant Case they invented what Mathematics: Studies of Complex amounted to sexual selection as a special Classroom Events. (Nemirovsky, R. case of natural selection. That they did not & Roseberry, A., Eds.). Lawrence have a name for this process shouldn’t take Erlbaum Publishers: New Jersey. away from the conceptual innovations involved in recognizing the ‘novelty’ and Darwin, C. (1859/1964). On the Origin of significance of sexual selection. Species by Means of Natural Selection or the Preservation of Summary Favored Races in the Struggle for When students are given opportunities to use Life. (facsimile of first edition, ed. their knowledge to explain interesting and Ernst Mar.) Harvard University appropriate evolutionary phenomena, their Press: Cambridge. potential for understanding evolutionary concepts increases. Here, we have described Donovan, S. (2001). “Using the nature of a course designed to engage students in evolutionary inquiry as a guide for using the natural selection model, which curriculum development”. Paper provides a rich context for students not only presented at the International to reason about evolutionary concepts such History, Philosophy, and Science as variation and differential survival but also Teaching Organization, 6th to use those concepts to explain changes in International Conference, Denver, populations over time. In developing this Colorado, 2002. course, we attempted to redefine the expectations for students in evolutionary Hafner, R. and Stewart, J., (1995). “Revising biology and to provide a picture of what explanatory models to accommodate curriculum designed with these goals in genetic phenomena: Problem mind might entail. Students in this course solving in the context of discovery.” were able to reason and argue from data, Science Education. 79 (2): 111-146. develop their own explanations for natural phenomena, and evaluate the hypotheses of Johnson, S. & Stewart, J. (2002). “Revising their peers—in sharp contrast to students in and Assessing Explanatory Models
Biology International Vol. 47 87 Stewart, Passmore, and Cartier in a High School Genetics Class: A Stewart, J. (1982). “Two aspects of Comparison of Unsuccessful and meaningful problem solving in Successful Performance.” Science science”. Science Education. 66: Education. 86: 463-480. 731-749.
Kitcher, P. (1984). “1953 and all that: A tale Stewart, J. & R. Hafner. (1991). “Extending of two sciences”. The Philosophical the conception of problem in Review. 43: 335–373. problem-solving research”. Science Education, 75 (1): 105-120. Kitcher, P. (1993). The advancement of science: Science without legend, Stewart, J., J. Cartier, & C. Passmore. objectivity without illusions. Oxford (2005). “Developing Understanding University Press: New York. Through Model-Based Inquiry”. In How Students Learn Science in the Laudan, L. (1977). Progress and Its Classroom. (Donovan, S. & J. problems: Towards a theory of Bransford, Eds.) The National scientific growth. University of Academies Press, Washington, D.C. California Press: Berkeley, CA. Stewart, J., J. Cartier, C. Passmore, J. Passmore, C. & Stewart, J. (2002). “A Rudolph, & S. Donovan. (2005). Modeling Approach to Teaching “Modeling for Understanding in Evolutionary Biology in High Science Education”. In Schools”. Journal of Research in Understanding Mathematics and Science Teaching. 39: 185-204. Science Matters (Romberg, T., T. Carpenter, and F. Dremock, Eds.). Pickett, S, J. Kolasa & C. Jones. (1994). Lawrence Erlbaum Associates: Ecological Understanding. Mahwah, New Jersey. Academic Press: New York.
Rudolph, J. (2000). “Reconsidering the ‘nature of science’ as a curriculum component”. Journal of Curriculum Studies. 32: 403-419.
Rudolph, J. & Stewart, J., (1998) “Evolution and the nature of science: On the historical discord and its implications for education”. Journal of Research in Science Teaching. 35 (10): 1069-1089.
Salmon, W. (1998). Causality and Explanation. Oxford University Press: New York.
Stewart, J. (1988). “Potential learning outcomes from problem solving in genetics: A typology of problems”. Science Education. 72 (2): 237-254.
Project MUSE 88
Cindy Passmore James Stewart is the received her Ph.D. in Associate Director of Curriculum and the National Center for Instruction at the Improving Student University of Wisconsin, Learning and Madison. She is a Achievement in Member of the Mathematics and Science/Math Initiative Science (NCISLA) and task force, University of is Professor of Science Education in the California System. 2005- Department of Curriculum & Instruction as present; California Math Science Teaching well as in the Institute for Environmental Steering Committeer, Fall 2004-present; Studies at the University of Wisconsin- American Educational Research Madison. His areas of expertise include: Association; National Association for student learning, problem solving, and Research in Science Teaching; National reasoning in science (particularly Science Teachers Association; Association evolutionary biology and genetics). He is the for the Education of Teachers of Science. founder of the "Modeling for Understanding Three of her recent grants from the National in Science Education" project. The project is Science Foundation are entitled: Inquiry Into based on the premise that students' learning Practice; Collaborative Learning at the of science should include gaining a facility Interface of Mathematics and Biology with conceptual knowledge, or "subject (CLIMB); and Collaborative Classroom- matter," and understanding the ways that Based Inquiry (CCBI). Her awards include scientific knowledge is generated and being an Early Career Research Affiliate of justified. The NCISLA researchers have the Center for Curriculum Materials in found that high school students can learn Science. Her motto is: “Students should science with understanding through have the opportunity to reason like scientists experiences in scientific inquiry, modeling, if we hope to ensure long-term and reasoned argumentation (justification). understanding and inspire greater numbers Extensive materials developed for of youth to pursue careers in science. instruction in evolutionary biology and Model-based instruction, in which students astronomy - using the model-based approach observe a phenomenon and then reason - are posted on the MUSE website through experimentation how that (www.wcer.wisc.edu/ncisla/muse) as a phenomenon occurred, provides a different resource for middle and high school science strategy for teaching science that has teachers nationwide. Stewart has been the demonstrated its value in achieving these recipient of the highest award given by the goals. If we can help teachers adopt National Association for Research in instruction that focuses on reasoning and Science Teaching. experimentation, our hope is that their students will be able to make better connections among the content they study..."
Biology International Vol. 47 89 Stewart, Passmore, and Cartier Jennifer Cartier is an Assistant Professor of Science Education at the University of Pittsburgh. She grew up in southern Maine and attended Williams College in the Berkshires of Massachusetts. Throughout high school and college, Dr. Cartier participated in a number of intensive research projects in the fields of molecular genetics and biochemistry, including summer internships at the Jackson Laboratory in Bar Harbor, Maine and the University of North Carolina at Chapel Hill. Her college thesis involved active-site mapping of the HIV-1 Reverse Transcriptase protein. Following college, Dr. Cartier earned a Masters degree in Biochemistry related to her work in virology at the University of Wisconsin: identifying functional domains of the anti-apoptotic baculovirus P35 protein. She received her Ph.D in Curriculum and Instruction at the University of Wisconsin-Madison. As the child, wife, and sister of teachers it was almost inevitable that her love of science would eventually be channeled into a career in education, and in 1994, she entered graduate studies in Science Education. Since then, she has been working primarily in the areas of curriculum development and teacher professional development in science education.
Project MUSE 90
How to become Pebb les and Bam Bam (or a practical approach to human evolution)
Joanna Fissenden
Kaikoura High School, Kaikoura, New Zealand, [email protected]
Human Evolution can be a daunting subject to teach and to learn, particularly as it is a dynamic topic! Year 13 students often complain of its relevance to them and struggle to understand the significance of events such as controlling fire or refining tools. At our particular school we found the topic was one that students were least successful in, had the highest dislike for and least amount of interest in. We felt we needed to try and change both the attitudes and level of achievement in the Human Evolution papers. The program we have used in our school has a practical base rather than theoretical. The students are basically encouraged to be hands on ‘cave men’ for the duration of the topic, culminating in a week of stone tool making, fire making, and preparing food. This presentation is to show what we do and maybe encourage others to consider some of our basic practical’s for use in their own programs. For us as a school the level of Y13 achievement has significantly improved and it has become a focal topic for many of our students.
Introduction Kaikoura is a small town on the East Coast % passing Human Evolution Paper compared with National Average of the south Island approximately 21/2 hours Kaikoura Y13's north of Christchurch. The main 80 National average 70 60
employment in the town is tourism, farming g 50 and fishing. It is a district of 4000 people 40 30 % passin with 1500 living in the township. Kaikoura 20 10 High School is a coeducational Year 7 -13 0 school at decile four (on a scale of 1-10, 2003 2004 2005 2006 2007 2008 Year poor to good). At present we have a role of 250 students. Y13 is normally a small year Figure 1: Percentage of Year 13 students passing National Human Evolution exam paper compared to the national group often not targeting further education average. or looking more to trades based courses. Although the biology course remains a Brief Lesson Outline reasonably popular option, the Human We start with the opposable thumb practical evolution section was suffering badly. – an oldie but a goodie, Students perform a When surveyed students were not interested range of tasks (doing up a button, tying a in the topic, found it too theory orientated, shoelace, texting while holding the phone, hard to see any relevance in it. Our national using chopsticks, picking up a coin off a exam results were embarrassing. We have desk, blowing up a balloon) and record how changed the course to a strongly practical easy the tasks are and how much they use base and although only a couple of years their thumbs while doing it. They then into it the results are improving (Figure 1).
Biology International Vol. 47 91 Fissenden repeat the tasks with their thumbs taped to from Larry Flammer and the ENSI website the side of their hands. (see end for website).
‘CSI’ skull awaiting muscle. Danielle making Oldowan potato tools.
Skulls Potato tools In most years we hire a set of hominid skulls To start tool making, after some theory we (although if they are unavailable there is an do the potato practical. This is an excellent excellent paper/web exercise at way of making Oldowan tools using www.biosciences.bham.ac.uk/links/teachers) teaspoons. Any potato will do but if for a set of exercises. Students initially put possible we use a red skinned one to show them into their idea of evolutionary order, the chips better. Holding the potato in one investigate cranial capacity with a series of hand students use a teaspoon held in the measurements and investigate male/female other fist to strike chips off one side of the differences in modern humans tool. It gives the students a good idea of the (themselves!). effort involved in making precise tools, illustrates basic shaping and end up looking CSI skulls – we a have three ‘CSI’ skulls, remarkably like the real thing. It also plastic skulls with facial markers and the shows what a mess can be made by doing clay to build muscle out of. We get students something essential! If you leave the potato to build the modern skull up looking at size tools on a windowsill for three – five days of muscle and attachment points, shape and then they darken and harden and end up bone size and compare to earlier skulls to looking exactly like the real thing, as well as see the difference in musculature to get being as hard as rock! them talking about functionality and diet etc.
Footsteps in time After various activities with whole skeletons and measurements of limbs we do a large scale activity called Footsteps in Time. We have a laminated diagram copy of the Laetoli track way blown up to actually size. We lay it down the side of the laboratory (or use a hallway) and next to it lay down a sand Adam making real rock tools. Zara selecting rocks for tools. track. Get your own students to walk down the sand track. See if they can work out Real tools height from footprints and stride length. Moving onto real tools and the slightly more Then do the same for the Laetoli prints and sophisticated Achulian style. We give compare. There is also another version students a selection of rocks to choose from using contour maps of the Laetoli prints – limestone, flint, river-rocks (greywacke) which we have formed into a laminated and they select what they think will make a puzzle. Both these excellent resources came good tool. They are given the guidelines of
How to become Pebbles and Bam Bam 92 having to make three precision tools – a skinner, a cutter and a third of their choice
Using stone tools to improve fire making. Rabbit skinned using stone tools, waiting for cooking fire.
(boys often try to make spear points, girls make food crushers!). Wearing safety glasses they go through the process of making these tools and refining the points/flakes. At this point we group them into ‘caves’ or tribes for the rest of their work as ‘cavemen’. Attempt to start fire to cook butchered rabbit.
Shelters Taking our groups we go out to a nearby riverbed and get the students to make a shelter from what is around them. We have been fortunate in the last couple of years to have had some cowhides given to us that can be used by a group if they are having no luck with the environment. Bow method of creating fire. Brute force method of creating fire.
Fire making The next step is to make fire. We provide the wood – mahoe, totara, kaikomako – all native which the Maori used but any soft and hard wood will work well (just make sure one is soft and one hard, or if you have exceptionally annoying students give them Thumb taped to side of hand for opposable thumb practical. treated timber!!). Some just use brute strength and rub one wood onto the other We then provide the groups with a freshly while others make bows to turn the wood. killed rabbit that they have to skin, gut and We used to use flax to make the bows but cook. Fish also work really well as long as string has slowly crept in. It is also it is something firm for them to try to cut important to have something that can be with their tools. Most succeed in some way used as tinder. It is a slow process but to get their animal to cooking stage but works well with patience and makes again it gives them a greater appreciation of students realise just how long it took to how small (to us) advances had a major restart fire , how much time was caught up impact on how these people lived, what they in preparing food and how little time there did and the time they had to develop would have been for things other than communication and social structures. surviving!
Biology International Vol. 47 93 Fissenden Domestication Being in a rural environment means that in some years we have the time for students to attempt to ‘domesticate’ (not that they are really wild) new chicks. Again just to give them an idea of the time and effort involved
Successful butchery of rabbits using stone tools. in livestock and how it would have started to change people ways of life in terms of where Cave painting they lived and how they lived. We have a very convenient concrete block wall that is easy to hose down to allow Conclusion groups to make their own cave paint stories This program has a very practical base of their group and their ‘life’ as cave men. which works well in a rural area like ours To make paint we use a variety of in season but many of these activities can be easily berries (blueberries and raspberries work adapted to work in more urban environments well!), watered down clay, charcoal – as well. The benefits to us as a school anything natural really! Then using twigs or teaching the unit are not only seen in the fingers they create their artistic masterpiece. improving exam results but the students interest level in increased, they are more focused, appear to have a greater understanding and feel for the ‘big picture’ side of the topic and as we normally run it towards the end of the year, they are often more relaxed going into exam time. For the full lesson sequence and any further information, please feel free to contact me
Oldewan potato tools. [email protected].
Spirituality Acknowledgements Using standard school modelling clay the University of Birmingham small groups that have worked together www.biosciences.bham.ac.uk/links/teachers throughout the previous ‘cave men’ Larry Flammer/ENSI activities come up with their own idea of www.indiana.edu/~ensiweb/lessons spirituality based on what would probably (Footsteps in Time worksheets) have been important to people at this time. Sonja Thomson, Riccarton High School. The make a clay figurine to either represent Peter Smith (2004) Y13 Biology Practical an ‘idol’ or something that would have been workbook. Educational Solutions, of significance to their group had they really Canterbury, New Zealand. existed in this time period.
Speech Our groups then develop their own speech/communication process and have to do a short skit to the rest of the groups to explain who they are as a people, where they are from, how they live and see if the other groups can understand or make out what they are trying to communicate.
How to become Pebbles and Bam Bam 94
Joanna Fissenden was born and raised in the South Island, New Zealand Jo went on to do an MSc in Ecology at Canterbury University then to work at NIWA while studying for a PhD in zooplankton ecology. After meeting her husband she changed tacks and retrained as a teacher of Biology and science. Currently she is teaching in a small rural school, Kaikoura High which she absolutely loves and juggling 4 small children at the same time.
Biology International Vol. 47 95 Fissenden Teaching “tree thinking”
Robert H. Cruickshank
Department of Ecology, Faculty of Agriculture and Life Sciences, Lincoln University, New Zealand, phone +64 (0)3 321 8355, fax +64 (0)3 325 3844, [email protected]
“Just as beginning students in geography need to be taught how to read maps, so beginning students in biology should be taught how to read trees and to understand what trees communicate” Robert O’Hara 1997
Introduction become increasingly apparent that the way Charles Darwin himself recognised the fact they are presented can lead us to interpret that an important consequence of his theory them in ways that may mislead us about the of descent with modification is that the evolutionary processes that created them. As evolutionary history of organisms can be phylogenies become more widely used it represented by a branching diagram similar will be increasingly important for biological to a tree; indeed, the only illustration in educators understand these issues and Origin of Species is just such a tree. communicate them effectively. Evolutionary biologists call these “phylogenetic trees” or “phylogenies” and Darwin’s trees they are ubiquitous in the technical literature In July 1837 Charles Darwin wrote at the of the field. As methods for reconstructing top of a page in his journal the words “I evolutionary history have improved there think” and then drew what has become one has been increasing interest in phylogenies of the iconic images of evolutionary in other areas of biology. This has lead to biology; a phylogenetic tree. Steve Jones, in the rise of “tree thinking”, a way of looking a recent radio documentary on the life and at biology that emphasises evolutionary work of Charles Darwin (BBC Radio 4 relationships (O’Hara 1997). While tree 2009) described this tree as “the most thinking has become commonplace among important diagram in biology”. People had professional biologists, it has not yet filtered used branching tree-like diagrams before to through to the popular media, or into the depict the similarities between things, but consciousness of the general public. As we this was different; Darwin’s tree represented have learned more about phylogenies it has shared evolutionary history rather than mere
Teaching “tree thinking” 96 similarity. Things that appear close together Common misconceptions in a phylogenetic tree are not necessarily A number of excellent resources are similar. In many ways crocodiles are more available explaining how phylogenetic trees similar to lizards than they are to birds, should be correctly interpreted (e.g. Tree nevertheless in a phylogenetic tree they Thinking Group 2004, Baum et al 2005, appear closer to birds than lizards. This is Crisp & Cook 2005, Baum & Offner 2008, because they share more of their Gregory 2008, Omland et al 2008, Sandvik evolutionary history with birds than they do 2008) however, phylogenies continue to be with lizards. It so happens that since the last misinterpreted, even by professional common ancestor of birds and crocodiles, biologists, and examples of such errors are the birds became highly modified, with the common not only in the popular media but evolution of flight, wings and feathers even in peer-reviewed journal articles. The among other things making them look problem is that we are more used to superficially very different to crocodiles, interpreting tree-like diagrams in terms of while crocodiles have retained many of their similarity rather than shared history. primitive features making them more closely Psychological and perceptual biases tend to resemble lizards than birds. A tree that mislead us, and this is often not helped by groups animals together on the basis of the ways in which phylogenies are similarity alone (often called a “phenetic” presented. This is not just a problem for the tree) would put lizards and crocodiles untutored, even professional taxonomists are together; however, a phylogenetic tree, apt to make such errors. In 2004, the editors which groups animals according to their of the journal Systematic Entomology got so shared evolutionary history will put tired of receiving manuscripts that contain crocodiles together with birds. one particular misconception about how phylogenetic trees should be interpreted that Notwithstanding recent media claims that they wrote an editorial about it (Krell & Darwin was wrong about the tree of life (e.g. Cranston 2004). Their particular problem Lawton 2009), a claim that has been was that they were continually receiving denounced as misleading hyperbole by manuscripts that used language such as many in the less mainstream, but arguably “primitive” or “basal” to refer to extant taxa. more scientifically literate, blogosphere (see They argued that living taxa always Coturnix (2009) for a list), phylogenetic represent a mixture of ancestral and derived trees remain a vital part of modern character states and therefore it makes no evolutionary biology and still have a great sense to describe a living organism as deal of explanatory power. We now primitive. Character states may be primitive, understand that hybridisation and horizontal but organisms themselves (unless they are gene transfer mean that there are fossils) cannot be. Since all living things connections linking different branches of the share a single common ancestor it makes no tree of life, both between closely related sense to describe any particular one of them species at the tips of the tree in the case of as primitive, basal, derived or any other hybridisation, and deeper in the tree in the form of words that implies they are more or case of horizontal gene transfer (Bapteste et less evolved than any other living organism. al 2005). Nevertheless, there is much that is As Darwin himself famously recognised, “it tree-like about the history of life on Earth, is absurd to talk of one animal being higher and for most purposes relationships between than another” (Darwin 1837). species are more accurately described by a tree than a network; trees remain uniquely The problem seems to have arisen in part appropriate visual metaphors for depicting from the way phylogenies are presented. It is evolutionary history. common to present trees in a “ladderised” form in which when a branch splits into two descendant lineages the lineage with the
Biology International Vol. 47 97 Cruickshank fewest taxa represented in the tree is always Another reason why extant lineages are put on the same side (usually the left, or the sometimes misrepresented as primitive is top). The problem with this is that we are that they have a particular character state used to reading in one particular direction that is considered primitive. An often quoted (left to right in English) and this example is the monotremes (the platypus arrangement of the tips of a tree leads us to and echidnas). These are mammals that lay see them in a particular way that has been eggs. As egg-laying is a feature shared with referred to as “reading across the tips” other tetrapods this feature is considered to (Gregory 2008). This means that for a be ancestral, i.e. it was found in the last ladderised tree we are always looking at the common ancestor of all mammals. This species-poor branches first and we seem to particularly conspicuous primitive feature have an inherent bias to interpret these has been retained in the monotremes and for species-poor lineages as primitive. As we this reason the monotremes themselves are scan from left to right we tend to interpret often described as primitive. However, there the tips as steps in a ladder of progression. are many other features of monotremes that But the number of species in a group has are not ancestral, i.e. they were not found in nothing to do with how primitive it is; it is the last common ancestor of all mammals merely a function of the species-richness of but have evolved in the monotreme lineage the taxon in question and the completeness since the monotremes split from the other of our sampling. It is also a consequence of mammals (e.g. venom, electroreception, a the particular point in evolutionary history at unique sex determination system). This is which we find ourselves, as lineages that are nicely illustrated in a figure from a paper in currently species-poor may have been much the journal Nature reporting the sequencing more diverse at earlier times in life’s history of the platypus genome (Warren et al. when lineages that are currently species-rich 2008). This figure shows a phylogenetic tree may have been represented by far fewer for the mammals, clearly indicating which species. If we interpret lineages as primitive features of monotremes are ancestral, and on the basis of their relatively poor number which have evolved since their split from of species then we would make different other mammals. Unfortunately, the news conclusions about which lineage is primitive article that accompanied this paper (Brown at different times in their evolutionary 2008) contains a different picture that is history, which is clearly absurd. Krell and much more misleading. Apart from the fact Cranston (2004) expertly demolished this that the relationships depicted are not those nonsense by showing that by collapsing reported in the paper being described either of the two basal clades in a tree we (Ducey 2008), the tree is skewed into a can derive a tree that could be peculiar ladder of progress that even has misinterpreted as suggesting that either of arrows on it leading from insects, via these clades is “primitive”. The truth of vertebrates, tetrapods and mammals, to course is that neither of these clades is humans, which are clearly meant to be primitive; in answer to their own rhetorical interpreted as the pinnacle of evolution. The question in the title of their editorial, neither blogosphere also had much to say about this side of the tree is more basal, even if one particular infringement of scientific common side is only represented by a single species. sense (e.g. RPM 2008). They go on to recommend that trees should be described in terms of sister-group Another problem with labelling a particular relationships rather than by using language taxon as primitive because it has a particular that could mislead us about the underlying feature that is considered to be primitive (an evolutionary processes that have created argument reminiscent of single-character them. taxonomy, which is now almost universally recognised as inappropriate and likely to mislead (e.g. Smith 2005)) is that it leads to
Teaching “tree thinking” 98 a circular argument. Once a taxon has been must be taken not to stretch the analogy labeled as primitive, then other features of beyond its limits. A particularly useful tool that taxon are interpreted as primitive, in this context is the “great clade race” merely because they are present in a (Goldsmith 2003). This makes the analogy “primitive” taxon. The fact that this taxon between organisms evolving through time has these features then adds weight to the and acquiring particular features argument that it is indeed primitive. It can (synapomorphies) which they pass on to be very difficult to break the circle of this their living descendants, and runners in a kind of reasoning. Arguments of these kinds race through a set of diverging paths in a can be found in the literature arising from forest that carry cards with them that are the search for the “most primitive living stamped with symbols as they pass through angiosperm”, an enterprise that has been checkpoints along the way. The symbols on very fashionable in recent years despite the cards carried by runners that take being founded on a misunderstanding, with different routes can be used to reconstruct a barely a year passing without a new map of the pathways, just as the features candidate being proposed (see Crisp & Cook shared between different organisms can be (2005) for examples). It would indeed be used to reconstruct their evolutionary very interesting to know which angiosperms history. This is a powerful analogy that can are on either side of the most basal split be extended a long way with the among them (i.e. which are sister taxa to all incorporation of such concepts such as the others), but if it turns out that one of convergent evolution (different checkpoints these clades consists of a single species then in the race using the same symbol), tree great care should be taken not to fall into the length (the total number of checkpoints), error of assuming that this monotypic clade and even punctuated equilibrium (the is ancestral to all the others; an extant taxon positions of the checkpoints along the cannot be the ancestor of another extant pathways). By using the great clade race at taxon. the beginning of a course it is possible to refer back to it when new, increasingly Tools for teaching “tree thinking” complex, concepts are introduced. This Although these issues are not conceptually helps students make sense of these ideas in complex, they can appear so to students. ways that are meaningful to them by This presents an opportunity to show them reference to a familiar analogy. how easily they can learn to understand ideas that may at first seem highly In accordance with the principle that the best theoretical and intellectually demanding. way to educate science students is to let The conceptual nature of these issues means them do science (DeHaan 2005), another that they tend to be more suited to active effective way of teaching tree thinking is to learning approaches in labs and tutorials, get students to construct their own rather than more traditional lectures, phylogenies. Research software for although a combination of different phylogenetic reconstruction is often quite approaches will mean that students with cumbersome and difficult to use, particularly different preferred learning styles have for novice students unfamiliar with tree opportunities to experience these ideas in building methods. One notable exception is ways that are meaningful to them. the program Mesquite (Maddison & Maddison 2009). This powerful program is One teaching method that is often cited as surprisingly user-friendly and students are effective is the use of analogies. Analogies able to get to grips with it very quickly. A can help students make meaning out of nice feature of the latest version (2.6) is the conceptually demanding material by simplification option which gives teachers drawing comparisons with situations with the ability to switch off parts of the program which they are more familiar, although care that the students will not be using to
Biology International Vol. 47 99 Cruickshank simplify the user interface and prevent doi:10.1662/0002- students becoming confused by unnecessary 7685(2008)70[222:PT]2.0.CO;2. options. Mesquite allows students to make their own character matrix, construct trees Baum, D.A., S.D. Smith, S.S. Donovan. for these characters, examine the way that (2005). “The tree-thinking challenge.” the tree length changes as they move Science 310: 979-80. branches around on the tree, and trace the doi:10.1126/science.1117727. evolution of each character separately so that they can see how it contributes to the BBC Radio 4. Darwin: In Our Time, overall tree length and how different program 3. 2009 (January 7th). characters conflict with each other. These http://www.bbc.co.uk/radio4/darwin/i features of the program can be used to nourtime.shtml. develop prescribed learning activities designed to teach particular principles, or Brown, S. (2008). “Top billing for platypus more open-ended projects that allow at the end of evolution tree.” Nature students to conduct their own investigations 453: 138-9. doi:10.1038/453138a. on groups of taxa of interest to them. Coturnix. Graham Lawton was wrong. A Conclusions Blog Around the Clock 2009 (January There are lots of useful resources that can be 25th). used to incorporate tree thinking into http://scienceblogs.com/clock/2009/01 teaching as an antidote to the more /graham_lawton_was_wrong.php. traditional approach of working thorough taxa in order from “lower” to “higher” Crisp, M.D., L.G. Cook. (2005). “Do early organisms. The understanding that students branching lineages signify ancestral gain from exposure to these ideas will traits?” Trends Ecol Evol 20: 122-8. empower them to use and interpret doi:10.1016/j.tree.2004.11.010. phylogenies in ways that are appropriate and Darwin, C. (1837). Notebook B. meaningful, and should encourage teachers to contemplate using the explanatory power DeHaan, R. (2005). “The impending of phylogenies and tree thinking more often revolution in undergraduate science in their own biology classes. education.” J Sci Edu Tech 14: 253- 69. doi:10.1007/s10956-005-4425-3. Acknowledgements I would like to thank Jim Shinkle (Trinity Ducey, P.K. (2008). “Picture not quite worth University, Texas) and Adrian Paterson 1,000 words in this case.” Nature 454: (Lincoln University, New Zealand) for many 27. doi:10.1038/454027d. enlightening discussions about the topics discussed in this paper. RPM. The great chain of phylogenetic wrongness. evolgen 2008 (July 18th). References http://scienceblogs.com/evolgen/2008/ Bapteste, E., E. Susko, J. Leigh, et al. 07/the_great_chain_of_phylogeneti.ph (2005). “Do orthologous gene p. phylogenies really support tree- thinking?” BMC Evol Biol 5: 33. Goldsmith, D.W. (2003). “The great clade doi:10.1186/1471-2148-5-33. race.” Am Biol Teach 65: 679-82. doi:10.1662/0002- Baum, D.A., S. Offner. (2008). 7685(2003)065[0679:TGCR]2.0.CO;2 “Phylogenies and tree-thinking.” Am . Biol Teach 70: 222-9. Gregory, R.T. (2008). “Understanding evolutionary trees.” Evo Edu
Teaching “tree thinking” 100
Outreach 1: 121-37. signatures of evolution.” Nature 453: doi:10.1007/s12052-008-0035-x. 175-83. doi:10.1038/nature06936
Krell, F.T., P.S. Cranston. (2004). “Which side of the tree is more basal?” Syst Robert Cruickshank is Entomol 29: 279-81. a lecturer in doi:10.1111/j.0307- entomology in the 6970.2004.00262.x. faculty of Agriculture and Life Sciences at Lawton, G. (2009). “Why Darwin was Lincoln University in wrong about the tree of life.” New Sci: New Zealand. He 34-9 (24th January). teaches courses in http://www.newscientist.com/article/ biology, population mg20126921.600-why-darwin-was- biology, insect diversity and ecology, wrong-about-the-tree-of-life.html. advanced entomology, conservation genetics, insect taxonomy, acarology, Maddison, W.P., D.R. Maddison. (2009). biological diversity, applied ecology, Mesquite: a modular system for entomology, and integrated pest evolutionary analysis, version 2.6. management. He is a member of the http://mesquiteproject.org. Entomological Society of New Zealand, the Systematics Association of New Zealand, O’Hara, R. (1997). “Population and tree and the Society of Systematic Biologists. He thinking in systematics.” Zool Scr 26: serves on the Editorial Boards of Zootaxa 323-29. doi:10.1111/j.1463- Molecular (systematics editor) and 6409.1997.tb00422.x. Systematic Biology. His current research is focused on acarology and entomology, Omland, K.E., L.G. Cook, M.D. Crisp. biodiversity assessment and monitoring, (2008). “Tree thinking for all biology: Evolutionary ecology of parasites, the problem with reading phylogenies Molecular ecology and conservation as ladders of progress.” BioEssays 30: genetics, phylogenetic structure of 854-67. doi:10.1002/bies.20794. ecological communities, phylogeography and spatial ecology, population genetics and Sandvik, H. (2008). “Tree thinking cannot evolutionary biology, systematics, be taken for granted: challenges for phylogenetics and comparative biology. teaching phylogenetics.” Theor Biosci 127: 45-51. doi:10.1007/s12064-008- 0022-3.
Smith, V.S. (2005). ‘DNA barcoding: perspectives from a “Partnerships for Enhancing Expertise in Taxonomy” (PEET) debate.’ Syst Biol 54: 841-44. doi:10.1080/10635150500354894.
Tree Thinking Group. Tree-thinking 2004. http://www.tree-thinking.org/.
Warren, W.C., L.W. Hillier, J.A. Marshall Greaves, et al. (2008). “Genome analysis of the platypus reveals unique
Biology International Vol. 47 101 Cruickshank
The teaching of Evolution in Sout h African schools: challenges and opportunities
Lorna Holtman
University of the Western Cape, Private Bag X17, Bellville, 7535 South Africa [email protected]
The South African Ministry of Education’s revised National Curriculum Statements (NCS) includes new learning areas and new topics especially in the Life Sciences Curriculum taught in grades 10 to 12. The topics include: fossils, natural selection, theories of mass extinctions and human evolution. Learning outcomes and assessment standards have been made clear in the policy document, however teachers find the content challenging to teach. They also find it challenging to design and implement appropriate teaching programmes. Evolution has never been explicitly taught in South African schools prior to the first democratic elections in South Africa which took place in 1994. The National Curriculum Statement indicates the specifically selected scientific content that should be taught and favours a teaching approach that illustrates the “nature of science” and promotes “science as a human activity”. This paper will discuss the challenges teachers face in regard to the teaching of Evolution in the South African context and will describe findings from research conducted in South Africa with Biology teachers.
Introduction The above is well known to South African Evolution has been identified as the unifying teachers, but offers a tremendous challenge principle for understanding the relationships when one considers that during their pre- among living things, the history of life on service teacher education programmes, earth, and the dependence of life on the teachers were not necessarily taught about physical world (AAAS, 1990; BSCS, 1993; Evolution before the abolishment of NRC, 1996). It has been identified as the Apartheid (pre-1994). This was prohibited unifying framework within which many because of the philosophy of Christian diverse biological facts are integrated and National Education policy of the National explained. Scientific literacy, which has government before the new democratic been identified as a central goal of South Africa came into being after the 1994 contemporary science education reform elections. This means that teachers might within the realm of biology, cannot be have very little background to teach about achieved without an understanding of the Evolution, unless they pursued a degree in nature of science and biological evolution the Biological Sciences at Baccalaureate (AAAS, 1993; NRC, 1996; BSCS, 1993). level. It is therefore most likely that at school level, the evolution-creationism debate was not an issue. It is of interest that
The teaching of Evolution in South African schools 102 the Nationalist Government’s belief in teacher professional development or in- Apartheid was based on Francis Galton’s service training as it relates to the teaching Eugenics Movement which grew out of the of evolution in South African schools. mistaken belief that Darwin’s “fitness” Challenges faced by teachers are presented. referred to as social fitness – the strongest, the wealthiest, the most intelligent were the The new curriculum fittest. The Afrikaaner Nationalists accepted The school system in South Africa consists this and applied it to race while rejecting the of 2 major bands: The General Education Darwin’s theory of evolution (Lever, 2002). and Training phase –GET- (Grades R-9) and the Further Education and Training band - In addition to this the policy of exclusion of FET- (Grades 10-12). The GET band black learners from science education (to a follows the Natural science learning area is large degree) enormously impacts and is an integrated curriculum and the curriculum impacting on science education reform in is composed of 4 strands (Matter and South African schools. South African Material, Planet Earth and Beyond, Energy school children have low levels of scientific and Change, and Life and Living) literacy as shown by the TIMSS studies (Department of Education, 2002). In the (international studies of mathematics and FET band students may select the Life scientific literacy) in which they participated Sciences as one of seven subjects toward the (Reddy, Kanjee, Diedericks and Winnaar, National Senior Certificate (Department of 2006). For various reasons outlined so far, Education, 2005). the South African school system has failed to prepare school children to benefit from A major challenge faced by teachers is that the insights of contemporary science, more they had to familiarize themselves with the specifically, the origin and evolution of life. new content in the curriculum which they were probably not exposed to before during The new curriculum contained in the their training. Teachers had to implement a National Curriculum Statements is a brand new curriculum, where their roles political and planned strategy of the South changed from implementers of a pre- African government to address inequalities packaged curriculum to one where they play of the past and to prepare a citizenry that is 7 different roles, among them, facilitator of informed and empowered. It is therefore an knowledge, assessor, and curriculum attempt to free the nation from its political developer. They were not specifically and disenfranchised past under an Apartheid trained for these roles. Training for the government and educational system. There implementation of the new curriculum were many innovations in the curriculum consisted of once off workshops, holiday aimed at achieving these goals; among these workshops, and very little support from include a focus on a learner–centered overstretched Curriculum Advisors approach to delivering the curriculum; employed by the education district offices to integration across the curriculum at the support teachers. Where the Natural lower grades; the removal of racially Science and Life Science was concerned, discriminating information from the learning teachers faced enormous challenges. materials and textbooks; the inclusion of Indigenous Knowledge systems as a theme Having to learn new educational principles in the Natural and Life Sciences Curriculum of integration and progression, they had to Statement; and the use of the word focus on these and above all on designing ‘Evolution’ in the Life Sciences Curriculum. learning programmes to attain the learning outcomes. The whole curriculum is In this paper I cover aspects of the training structured around the 3 Learning Outcomes needs of teachers in terms of pre-service (LO) and ultimately toward the teacher education. I will also touch on developmental and critical outcomes.
Biology International Vol. 47 103 Holtman Learning outcomes for GET (FET as well) never address ultimate causation – that is are: ignoring the central concept of modern 1. LO1: Scientific investigations – the biology – Darwinian evolution. In the end, learner will be able to act evolution by natural selection remains the confidently on curiosity about most controversial topic in schools natural phenomena, and to (Dempster and Hugo, 2006). investigate relationships and solve problems in scientific, technological The curriculum does contain the concepts and environmental contexts. necessary to lay a foundation for the 2. LO2: Constructing scientific understanding of Darwinian evolution but knowledge – the learners will know does not provide teachers with a plan or a and be able to interpret and apply sequence of steps to get there (Dempster and scientific, technological and Hugo, 2006). Teacher training is not at the environmental knowledge. level where we can call them specialized to 3. LO3: Science, society and the teach evolutionary biology – this requires environment- the learner will be that teachers have a deep understanding of able to demonstrate an evolution so that they can put together the understanding of the concepts covered in the curriculum at the interrelationships between science, different grade levels in a coherent structure- technology and society and the in this way evolution can emerge as a the environment. overarching principle of biology and not “just a theory” – the common misconception The time spent on science in the GET is our teachers buy into. Even in the Life 13% of curriculum time, 140 hours per year Science curriculum where the word per grade. Seventy percent is prescribed “evolution” is used Dempster and Hugo core knowledge and 30% is teacher selected (2006) point out that the full impact is content chosen by the teacher to enhance reduced by the separation of genetics from progress toward achieving the learning evolution in the examination. Genetics is in outcomes (Dempster and Hugo, 2006). Paper 1 and Evolution is in Paper 2.
The time spent on Life Science in the FET is Teachers report a general lack of support 170 hours per year per grade, 80% core and lack of training. I am not aware that knowledge is specified in curriculum and curriculum advisors themselves have 20% is at the teacher’s discretion. The received any training to ‘teach’ teachers curriculum provides ample opportunity to about the developments in Evolutionary develop biological concepts outside of what Biology. Teachers report about once-off is prescribed content and there exists enough workshops which do not make a major opportunity to include more information and difference in terms of preparing them to ideas on evolution (Dempster and Hugo, teach the new topics – such as Evolution and 2006). Indigenous Systems. What we are therefore facing is implementation without adequate Teacher choices and challenges with training of teachers to teach the regard to teaching evolution fundamentals of Evolutionary Biology. Teachers can avoid the word evolution in Furthermore, the curriculum statements their teaching up to grade 12 (changed to emphasize the need to consider alternative grade 10 in 2009). Even though the theories or ways of knowing – in our case, curriculum contains concepts which are able faith-based and indigenous knowledge to provide a solid base for learning about systems. This places added pressure on the evolution later on, the danger is that teachers teacher (e.g. multicultural class, different can focus teaching biology at the level of faiths, indigenous knowledge systems). descriptive and functional biology, and
The teaching of Evolution in South African schools 104
In some cases, there is control by officials as life on Earth and the most complete record to what kinds of exposure teachers get. In of the ancestry of mammals as well as some case there can seen an agenda to put having over one third of the entire fossil forth intelligent design as an equal theory record of human evolution in Africa and the question is: should religion be taught (Rubidge, 2005). in a science class? In a multicultural and multi-religious society this is not Lack of material resources (and unequal unproblematic. Denying teachers the ability resources) and problems of access to the rich to discuss religious issues in the science natural resources we find in South Africa classroom could be seen as undermining (e.g. Cradle of mankind) hinder students religious rights. There are parents and from learning first hand about the students who do not want to learn about importance of Africa in terms of evolution due to their religious convictions evolutionary biology and furthermore we or students are non-receptive students miss the opportunity to concretise and because they are not open to evolution demystify the topic for our students. Based because of their faith. Then there are those on the fact that evolution is an abstract and who are not able to make the conceptual and generally non-observable phenomenon, the inferential leaps to understand evolution. NABT advises that students be engaged in learning about evolution in the most Why teaching evolution is so important – effective level available; the concrete, what is actually taught and what should hands-on laboratory experiences (McComas, be taught? 1994). For South Africa – knowledge of evolution especially if taught in a way that builds on Data from surveys of teachers in the Darwin’s argument as it developed, can lead Western Cape and Northern Cape regions of to critically thinking students – this can South Africa appear to indicate that in terms stand them in good stead in their daily lives of teacher content knowledge for Biology as we try to combat the scourge of and specifically evolution, research HIV/AIDs, multi-drug resistant TB and generally has revealed that the majority of other problems facing African children with teachers of science lacked the most regard to human life on earth (Gevers, fundamental knowledge in the new learning 2002). areas. Therefore in terms of teacher training needs (pre-and in-service), teachers need As Lever (2002) points out South Africa’s access to refresher courses which focus on contribution to palaeontology is of central the content of modern biology. Teachers importance since we have rich remains of need to be challenged to adapt their teaching the first Homo sapiens sapiens. Darwinian styles and to approach their teaching evolution is part of scientific literacy in a differently; they should be shown how to variety of fields beyond the life sciences. include innovative practices which include While we have these rich resources our teaching to develop critical thinking skills, learners view science as boring and and adopting a Pedagogical Content incomprehensible. Tourists are interested in Knowledge (PCK) approach in addition to our heritage yet our own learners know understanding subject matter knowledge. nothing of it. Rubidge (not dated) comments They generally lack curriculum and policy on how exciting it is to collect fossils but knowledge and hence cannot implement how easy it is to damage them and lose what they are not familiar with. valuable evidence. He believes that South Africa should formulate a policy aimed to The understanding of the nature of science protect the fossils while still promoting seems to be a prerequisite for the tourism. South Africa’s fossil record is understanding and accepting of the theory of unique in that it has the oldest evidence of evolution and its proper presentation in the
Biology International Vol. 47 105 Holtman life science classroom thereof. McComas things. The bible is the justification for (1998) said “by incorporating the nature of origins as it goes step by step. I understand science while teaching science content, their (evolutionists) argument, but I do not humanizes the science and conveys a great believe it. (WC T15). adventure rather than memorizing trivial No one checks whether they do or do not outcomes of the process”. Good (2001) teach what is prescribed in the curriculum. further said that, “nature of science idea is likely to be effective if it is blended in with Teachers are supposed to be involved in content instead of being taught separately or learning support materials development, at the beginning of the unit”. McComas however, they are not necessarily trained to (1991) claim that the “misconceptions about do this in the pre-service curriculum and do science are most likely due to the lack of not have the time to focus on this task philosophy of science content in teacher (Fullard and Holtman, 2004). They prefer education programs…”. pre-packaged curriculum. This is one area of training that should be encouraged as new The Curriculum Advisors’ daily jobs appear ideas emerge at a rapid pace in Biology and to be focused on showing teachers learning support materials will become moderation processes rather than playing a dated at some or other stage. Therefore the more holistic role in curriculum advisory focus in teacher training should be to support. This is largely due to the fact that encourage teachers to keep up to date with there are so few Curriculum Advisors developments and to show them how to available to visit and advise the large access information. Digital and information number of schools; or because they are literacy aspects of the pre-service teacher probably out of touch themselves with the training should be improved in this regard. demands and content of the new curriculum; and in some cases they might find it difficult to work with the E-word because of their Conclusion own religious convictions. More than 300,000 school teachers are affected by the Curricula changes and it We do not know what teachers actually appears that the current teacher pre-and in- teach in the privacy of their classrooms. A service teacher training is not reaching a teacher we interviewed gave us a glimpse large number of teachers. Teachers report into this. It appears that since evolution is that they are willing to attend workshops the last section in the syllabus for each grade and courses that “don’t not waste my time level (Grades 10-12), and the weighting for and will be meaningful to my learners” it is very low, therefore teachers apparently (personal communication with Teacher, avoid teaching that section. Teachers report January 2009). There is therefore a role for that they would like to teach creationism the institutions who prepare teachers for the alongside evolution so that students get the workforce in more ways than they are full picture and not the one-sided view of currently engaged with the needs of life on earth. Furthermore, some teachers do teachers. Universities should form a support regard the teaching of evolution in schools structure for teachers and Curriculum as a personal attack on their religious Advisors and work together to support beliefs. One teacher sums up her rejection of teachers. The pre-service teacher evolution as follows: framework needs to be redesigned ensuring that the teacher as life-long learner is I understand their argument but I do not equipped to keep abreast of research in believe it. Large-scale evolution is fictitious biology and education. In this regard, the for me; there really is no proof, there are literature confirms the important relationship gaps in the fossil record. There is no solid between the understanding of the nature of evidence for me that things come from other science and domain-specific knowledge, in
The teaching of Evolution in South African schools 106 this case, evolution (Holtman, 2000). The Guidelines: Life Sciences. Department latter is also a central principle of biology, of Education, Pretoria and therefore this relationship has far reaching implications for student Dempster, E.R., & W. Hugo. (2006). understanding of biology. Teacher pr- “Introducing the concept of evolution service training should include these aspects into South African schools.” South as well. African Journal of Science 102: 106- The new curriculum obviously had as a 112. major intention to transform the lives of all South Africans and to promote equal Fullard, D., Holtman, L. and Wagiet, F. opportunities to quality learning for all. In (2004). “Biodiversity Education: addition to this, the curriculum for science Challenges facing teacher professional and mathematics is geared toward preparing development processes.” Royal Soc.- a new cadre of scientifically literate NRF - Science in the New South Africa citizenry capable of high level critical Scientific Meeting Held at the Sheraton thinking to enable our citizens to participate Hotel, Pretoria, 23-24 August 2004. and contribute on the international stage. Teachers as agents of change can help us Gevers, W. (2002). Comment and response achieve these goals- with the right training to ‘Science, Evolution and Schooling and the knowledge to teach the principles of in South Africa’. The Architect and Darwinian evolution explicitly and directly the Scaffold: Evolution and Education so that students are exposed to one of the in South Africa. Human Sciences key underlying theories explaining life on Research Council Press: Cape Town. earth. Good, R. (2001). “Habits of mind associated References with science and religion: Implications American Association for the Advancement for Science Education.” Paper of Science. (1990). Science for All presented at the Sixth International Americans. Oxford University Press: History, Philosophy & Science Washington DC. Teaching Conference, Denver.
American Association for the Advancement Lever, J. (2002). Science, Evolution and of Science. (1993). Benchmarks for Schooling in South Africa. In Wilmot Scientific Literacy. Oxford University James and Lynne Wilson (editors). Press: Washington DC. The Architect and the Scaffold: Biological Science Curriculum Study Evolution and Education in South (1993). Developing Biological Africa. Human Sciences Research Literacy. Kendell/Hunt Publishing Council Press: Cape Town. Company: Colorado Springs, CO. Holtman, L.B. (2000). The Effects of the Department of Education. (2002). Revised Laboratory on College Students’ National Curriculum Statement for Understanding of Evolution: Grades R–9 (Schools): Natural Implications for Conceptual Change. Sciences. Government Gazette 26. No. Available via Bell-Howell Publishers. 23406. Department of Education, ISBN: 9998685 Pretoria. National Research Council (1996). National Department of Education. (2005).National Science Education Standards. Curriculum Statement Grades10– National Academy Press: Washington, 12(General). Subject Assessment D.C.
Biology International Vol. 47 107 Holtman Reddy,V., A. Kanjee, G. Diedericks, and L. Winnaar. (2006). Mathematics and Science Achievement at South African Schools in TMSS 2003. . Human Sciences Research Council Press: Cape Town.
Rubidge, B. (not dated). The Karoo, a Geological and Palaeontological Superlative: Economic Potential of Deep History. http://www.aridareas.co.za/pdf Downloaded 9 June 2009.
Rubidge, B. (2005). “The Karoo – a fossil Mecca.” Quest 2 (1): 16-19.
Lorna Holtman is a South African who lives in Cape Town, South Africa. She completed her PhD at Louisiana State University, Baton Rouge, LA in 2000. Her PhD thesis examined the importance of the biology laboratory in facilitating conceptual change. She is currently the Director of Postgraduate Studies at the University of the Western Cape South Africa. Lorna is the current chairperson of the South African National Committee chairperson of the International Union of Biological Sciences (IUBS) and is an Executive Member of IUBS, Vice President of the Commission on Biology Education (CBE) and Africa representative.
The teaching of Evolution in South African schools 108
The Case of the Protective Prot ein: Using a population genetics simulation in an undergraduate lab course to test hypotheses for the evolution of an HIV resistance allele.
Anton E. Weisstein
Affiliation Department of Biology, Truman State University, Kirksville, MO 63501-4221 U.S.A., [email protected]
Student concepts of evolution often rely exclusively on a simplified and deterministic understanding of natural selection, with little thought for stochastic forces such as genetic drift. This paper describes a lab module in which students in an undergraduate genetics course use an Excel-based simulation to test hypotheses concerning the evolutionary history of an allele conferring protection against infection by HIV. In the process, students develop a clearer sense of how both selection and drift contribute to a population’s evolution, and learn how population genetics principles can be applied to concrete biological questions.
Introduction Unfortunately, most college students’ When Darwin introduced the theory of conception of evolution relies on evolution by natural selection in 1859, his teleological ideas of “progress” and a vague otherwise thorough discussion lacked one sense that organisms “try” to adapt (Sinatra key component: a specific mechanism of et al. 2008). According to this view, inheritance. Even after Mendel’s work was beneficial mutations rapidly and inevitably rediscovered in 1901, it was not until the spread throughout a population, while 1920s and 1930s that the principles of harmful ones are eliminated just as rapidly, Mendelian genetics were fully integrated leading to a genetically uniform and well- into Darwin’s theory. This work, led by adapted population. Students holding this R.A. Fisher, J.B.S. Haldane, and Sewall view may resist the idea that an allele’s Wright, yielded mathematical models of effect may depend on context (i.e., the same changes in allele frequency under a variety allele can be beneficial under some of ecological, genetic, and population-level environmental conditions and harmful under factors. In particular, they expanded the others), and can seldom adequately reconcile treatment of evolution to encompass not their mental model with the existence of only natural selection, but also other neutral genetic variation. Moreover, evolutionary forces such as migration students’ simplistic concept of evolution between populations, de novo mutation, and limits their ability to understand stochastic random genetic drift. processes such as genetic drift (Garvin- Doxas and Klymkowsky 2008). Students typically equate stochasticity with complete
Biology International Vol. 47 109 Weisstein randomness, and hence cannot see how been used to estimate that the Δ32 allele population geneticists can predict, for originated between 11 and 75 human example, the statistical likelihood that a new generations ago (Stephens et al. 1998). If allele will become fixed within a population, these estimates are correct, intense selective or the time required to do so. pressures would have been needed to raise the allele’s frequency to its present levels in In this paper, I present a classroom module such a short time period, raising speculation in which students directly confront the that Δ32 might also have conferred interplay between natural selection and resistance to widespread historical European genetic drift through analyzing a putative epidemics such as the bubonic plague instance of recent human evolution. We (Stephens et al. 1998) or smallpox (Galvani begin by reading a primary article on the and Slatkin 2003). evolutionary history of an allele (CCR5Δ32) that confers resistance to HIV-1 infection. Before lab, students are assigned to read the Students then use a population genetics Stephens et al. article, focusing on the simulation to test the article’s hypothesis details of the CCR5 system and on the that this allele has experienced intense methods and main assumptions used to selective pressure to drive it to its current estimate the age of the Δ32 allele. In class, frequency, and use their results to propose we first review this material, then begin the historical hypotheses (e.g. bubonic plague, computational portion of the lab module. smallpox) for that selective pressure. Starting the Simulation Background To model the evolution at the CCR5 locus, CCR5 is a chemokine receptor expressed on we use the population genetics simulation the surface of T cells, macrophages, and Deme 2.2 (Weisstein and Barnes 2007). several other cell lineages (Samson et al. Deme is a Microsoft Excel-based workbook 1996). Its exact role in immune function that combines the effects of natural remains unknown, and indeed few ill effects selection, genetic drift, mutation, and have been reported in the many individuals migration for a one-locus, two-allele system. who lack a functional copy of the receptor For this module, we use a modified version (but see Glass et al. 2006). However, many that simulates only drift and selection, then strains of HIV-1 use CCR5 as a co-receptor reports the number of generations required to fuse with and infect host cells. In for the Δ32 allele to reach a frequency of particular, this is true for the macrophage- 10% (its prevalence in a representative tropic virus strains that are currently population of Northern European ancestry). believed to initiate most new infections Both to encourage discussion and due to (Deng et al. 1996, Dragic et al. 1996). limited numbers of computers, students In 1996, Huang et al. reported that a 32-bp work in groups of 2–4 per computer. deletion in the CCR5 gene appeared to confer protection against HIV-1. Our first goal is to determine whether there Specifically, heterozygotes for this Δ32 is significant evidence that the Δ32 allele allele appeared to progress more slowly to has historically experienced any natural full-blown AIDS, while Δ32/Δ32 selection. To do so, we calculate how long homozygotes had almost complete immunity it would take for a newly arisen Δ32 allele to to HIV-1 infection. Interestingly, while the reach its current frequency under a null Δ32 allele is fairly common in Northern hypothesis of neutrality. Students therefore European populations (~8–14%), it is rare or begin by determining the appropriate entirely absent in African and Asian parameter values to enter into the simulation populations. Coalescent methods and (Fig. 1) and defending their decisions. For analyses of linkage disequilibrium between example, students may consult the Stephens CCR5 and nearby genetic markers have
The Case of the Protective Protein 110 et al. article for the effective size of the figure. Extending the simulation to more historical Caucasian population (Ne=5,000); trials and 10,000 generations, students find however, they must reconcile this that the Δ32 allele reaches its target 10% assumption with the larger census size frequency in only about one out of every (N=10,000–100,000) and recent population 1,000 trials under a neutral model. growth also described in the article. To help students calculate the Δ32 allele’s initial Next, students analyze models of positive frequency p0, we first assume that all copies selection for the Δ32 allele. For the sake of of the allele trace back to a single, original simplicity, we assume complete dominance mutant. Students are then asked to calculate (W++ = 0.70–0.99, W+Δ = WΔΔ = 1). Students the frequency of that mutant; in a diploid usually predict that the Δ32 allele will population of 5000 individuals, this rapidly sweep through the population, and corresponds to p0 = 1/(2N) = 0.0001. are surprised to see that genetic drift still Finally, since they are currently testing the eliminates the allele in more than half the neutral hypothesis, they set all genotype trials (depending on the intensity of fitnesses to one. selection). I ask students to repeat their analysis many more times until they are confident in the surprising result: new alleles are usually eliminated by genetic drift within a few generations, even if those alleles are beneficial. We take a few minutes as a class to explain this conclusion in light of specific mechanisms of genetic drift, such as random deviations from expected Mendelian proportions when only one copy of an allele is present in a population (Fig. 2).
Fig. 1 A screenshot of the simulation. Shaded boxes in column H mark parameters whose values can be adjusted by students; here, parameters are set to model the neutral hypothesis. Cell G9 reports that, in this particular trial, the Δ32 allele was lost to genetic drift before reaching a frequency of 10%. The error messages in cells B17–D17 indicate that the allele was also lost in each of the 199 other trials run so far; as a result, the program cannot compute means or confidence intervals for the time required to reach 10% frequency.
Having determined and entered appropriate parameter values, students are now ready to run the simulation. A built-in macro in the modified version of Deme allows them to perform multiple runs and tabulate the Fig. 2 An illustration of genetic drift as a deviation from expected Mendelian ratios. Each oval denotes one diploid results with a single mouse click. Figure 1 individual. Even if every individual produces two offspring, shows a typical result from a set of 40 trials: only 50% of parents on average pass both of their alleles to the next generation; thus, new alleles are often lost within a in every case, the Δ32 allele’s frequency few generations. fluctuated between zero and 1% for fewer than 200 generations before being lost to At this point, I remind students that our genetic drift. As a result, the simulation primary goal is to not to estimate the cannot estimate the time required for the probability that a newly arisen Δ32 allele Δ32 allele to reach a frequency of 10%, as will eventually reach a frequency of 10%, indicated by the error messages shown in the
Biology International Vol. 47 111 Weisstein but rather to estimate the amount of time required to do so. Trials in which new alleles are eliminated by genetic drift thus do not represent useful data points. Since we need several hundred successful trials for our statistical analysis (see below), one option would simply involve continuing to run trials until enough of them have been successful. For example, we previously found that the Δ32 allele reaches 10% frequency in approximately 1 in 1,000 trials under the neutral model, so we could attempt to generate 200 successes simply by running about 200,000 trials. Faced with this prospect, students usually leap at the proffered alternative: taking a few minutes Fig. 3 A coalescent model. In this model, the simulation begins at the current frequency of the Δ32 allele, p = 0.10 to devise a more efficient simulation 0 strategy. (point A). Time is then run backward (note direction of the x-axis) until the Δ32 allele reaches a frequency of zero (point B). The Coalescent Model As we have seen, a conventional simulation To implement a coalescent model, we use approach to simulation is inefficient for the another modified version of Deme 2.2 in Δ32 allele: the majority of trials lead to which the standard recursion equations of unusable results. I frame the problem using population genetics have been inverted, the following verbal summary and prompt: allowing us to use the current allele frequencies to calculate those in the previous “As we’ve seen, starting with the new generation. Once again, students must mutation and then going forward in time determine appropriate parameter values for to the present level doesn’t work well the neutral hypothesis. The effective because we usually lose the allele to population size and genotype fitnesses genetic drift. But we want to measure remain unchanged from the prospective the length of time between when the model (Ne = 5,000, W++ = W+Δ = WΔΔ = 1). allele originates and when it reaches its However, for the coalescent model, students current level of 10%. Can anyone think set the Δ32 allele’s frequency to its current of an alternative to our basic approach— level (p0 = 0.10) and measure how long it instead of starting with the original takes the Δ32 allele to reach a frequency of mutation and going forward in time until zero. As before, each group of students runs we reach 10%, what else could we do?” the simulation 40 times to obtain a distribution of coalescence times.1 In response, several students usually propose reversing the time axis to track the Δ32 allele backward from its current level down 1 to a single copy (Fig. 3). As this In 10% of trials, the Δ32 allele becomes fixed rather than being lost. This outcome would imply that the retrospective approach is the central insight Δ32 allele predates the wild type, which seems behind the field of coalescent theory, I unlikely given the former allele’s restriction to briefly discuss coalescent models to help Caucasian populations (Stephens et al. 1998). students clearly distinguish them from the Students therefore re-run any such trials. By contrast, prospective models they have already individual trials in which the Δ32 allele does not coalesce within the first 10,000 generations are studied. extended until coalescence occurs, to avoid biasing our estimate of average coalescence time.
The Case of the Protective Protein 112
Next, students are asked to find a words, unless there is a flaw in Stephens’ nonparametric 95% confidence interval for analysis (see Discussion), it is very unlikely the Δ32 allele’s coalescence time. We begin that the Δ32 allele could have reached its by determining the total number of trials we current levels so quickly under genetic drift conducted as a class and calculating how alone. Instead, we conclude that the allele many of those trials will be present in each must have been favored by natural selection. 2.5% tail of the distribution. For example, a class containing six student groups will Our next question, naturally, asks how much generate a total of 240 trials; after pooling selection is required to take an allele’s these, we discard the top 2.5% (6 trials) and frequency from nearly zero to 10% in only the bottom 2.5% (6 trials) to arrive at a 95% 28 generations. Students therefore repeat confidence interval (Fig. 4). the above analysis for a range of selection intensities. Even weak selection substantially lowers the coalescence times, so each individual student group can now conduct their own set of 240 trials (or more, if desired). Any value of the selection coefficient s whose 95% confidence interval does not include a coalescent time of 28 generations is rejected, and this process continues until students have identified the range of selection coefficients consistent with Stephens et al.’s estimate of the allele’s age. Again, exact results will vary from one Fig. 4 Coalescence times for 240 simulation trials under the lab group to the next, but ranges of s ~ 0.25– neutral hypothesis (mean 5100 generations; range 340 – 48,278). The upper 2.5% and lower 2.5% of trials are 0.45 are typical. excluded to compute a nonparametric 95% confidence interval for coalescence time (474 – 23,178 generations). Finally, we relate these results back to a
larger question: what specific factors might Testing Hypotheses: Selective Pressure on be responsible for the intense selective Δ32 pressure we have just inferred? First, we Due to the stochastic nature of the step back from the mathematics for a simulation, individual classes’ exact results moment to contemplate the biological will vary, but typical results indicate that a meaning of a given selection coefficient. neutral allele would take well over 100 Because selection coefficient is defined as generations to reach a frequency of 10%. the complement of fitness (s = 1 – W), a For example, one lab section estimated a coefficient of 0.25, for example, would time to coalescence between 469 and 16,844 2 mean that CCR5+ homozygotes would have generations ago. By contrast, based on only 75% as many offspring on average as analysis of linkage disequilibrium with two individuals with at least one Δ32 allele. nearby genetic markers, Stephens et al. Thus, our previous estimate of s ~ 0.25–0.45 (1998) estimate that the CCR5Δ32 allele suggests a history of exceptionally strong arose approximately 27.5 generations ago, selection, roughly on a par with that with a 95% confidence interval of 11–75 experienced by a mosquito population generations. Students are asked to interpret exposed to DDT (Curtis et al. 1978). Next, the disparity between these two estimates, we convert the estimate of 28 generations to leading them to the conclusion that at least an absolute time scale. Human generation one estimate must be wrong. In other time in coalescent studies is usually estimated as approximately 20–25 years, 2 This wide range of variation is typical of random- implying that the Δ32 allele arose walk processes. approximately 1298–1438 C.E. Finally,
Biology International Vol. 47 113 Weisstein students are asked to propose specific modify the simulation to reflect changes in hypotheses about what factors acting on the selection intensity. Another extension of the Caucasian population during this time module is made possible by a follow-up to period might have imposed the necessary the Stephens et al. article published by some amount of natural selection. Students are of the same authors (Sabeti et al. 2005). usually quick to suggest the bubonic plague, Using more detailed genetic maps, these a hypothesis also advanced in the Stephens authors conclude that the original paper et al. article (2008). underestimated the age of the Δ32 allele, and gives a revised estimate of 3150–7800 years Discussion (~126–312 generations). Reading this By design, this module introduces only a second article can motivate a discussion of few concepts (linkage disequilibrium, the provisional nature of scientific coalescent theory) that students have not knowledge, while also allowing already encountered during course lectures. straightforward reanalysis using the newer Instead, the emphasis is on having students estimate. synthesize and apply abstract principles of population genetics to a specific biological One of this module’s most rewarding question. For example, while students have aspects has been the extent to which it previously learned that mutation generates engages students in population genetics. In the genetic variation upon which natural previous years, I have struggled to convey selection acts, most do not fully appreciate the intellectual excitement of this field to the corollary—that new mutations originate students: some are put off by the as a single copy within a large population— mathematics involved, while others tend to until they begin to determine appropriate view it as an abstract exercise of little parameter values for the simulation. practical importance. The idea of an HIV- Similarly, describing the stochastic nature of protective allele, however, effectively grabs genetic drift and showing sample results the attention of all but the most jaded proved much less effective than having student and brings them into the students perform their own trials and investigation. Moreover, because the analyze the amount of variation that simulation handles many repetitive tasks resulted. In interviews after completing the (e.g., running and tabulating multiple trials), lab, several students independently stated students can devote their full attention to that it had helped them to appreciate that more intellectually rewarding tasks: microevolution encompasses more than just translating the assumptions of a neutral natural selection, and to understand how the model into specific parameter values, individual evolutionary forces we had attempting to explain why favorable alleles discussed in class interact within a real are often eliminated, and interpreting the population. biological meaning behind specific evolutionary scenarios. The module thus Additionally, the combination of a research enables students to learn population genetics article with a simulation facilitates further in a research-like environment, applying exploration of related questions. For core principles to address a substantive real- example, the activity described above world question. assumes that the CCR5 allele experiences a constant intensity of natural selection, but Acknowledgments the mortality caused by proposed agents I would like to thank my colleague Tim such as bubonic plague and smallpox has Walston for valuable comments on this clearly not been uniform over historical manuscript, as well as former students Tad time. Similarly, human population size has Dallas and Mitchell Nuhn for sharing their not remained constant over the past 700 perspectives on the module. years. With some assistance, students can
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Open Access allele in HIV-1 transmission and disease The modified versions of Deme 2.2 and progression.” Nat Med. 2: 1240-1243. detailed instructor guide for this module are available at the Deme website (see Sabeti, P.C., E. Walsh, S.F. Schaffner, et al. references, Weisstein and Barnes). These (2005). “The case for selection at CCR5- materials are distributed under a version of Δ32.” PLoS Biol. 3 (11): 1963–1969. the GNU Free License, which permits any noncommercial use, distribution, Samson, M., O. Labbe, C. Mollereau, et al. modification, and reproduction, provided the (1996). “Molecular cloning and original author(s) are credited and any functional expression of a new human modifications clearly attributed. CC-chemokine receptor gene.” Biochemistry. 35: 3362-3367. References Curtis, C.F., L.M. Cook, R.J. Wood. (1978). Sinatra, G.M., S.K. Brem, E.M. Evans. “Selection for and against insecticide (2008). “Changing minds? Implications resistance and possible methods of of conceptual change for teaching and inhibiting the evolution of resistance in learning about biological evolution.” mosquitoes.” Ecol Entomol. 3 (4): 273– Evo Edu Outreach. 1 (2): 189–195. 287. Stephens, J.C., D.E. Reich, D.B. Goldstein, Deng, H.K., R. Liu, W. Ellmeier, S. Choe, et al. (1998). “Dating the origin of the D. Unutmaz, M. Burkhart, et al. (1996). CCR5-Δ32 AIDS-resistance allele by the “Identification of a major co-receptor for coalescence of haplotypes.” Am J Hum primary isolates of HIV-1.” Nature. 381: Genet. 62: 1507-1515. 661-666. Weisstein, A.E., W. Barnes. (2007). Deme Dragic T., V. Litwin, G.P. Allaway, et al. 2.2. (1996). “HIV-1 entry into CD4+ cells is http://www.bioquest.org/esteem/esteem_ mediated by the chemokine receptor CC- details.php?product_id=193. CKR-5.” Nature. 381: 667-673.
Galvani, A.P. and M. Slatkin. (2003). “Evaluating plague and smallpox as historical selective pressures for the CCR5-Δ32 HIV-resistance allele.” Proc Nat Acad Sci USA. 100: 15276-15279.
Garvin-Doxas, K., M.W. Klymkowsky. (2008). “Understanding randomness and its impact on student learning: lessons learned from building the Biology Concept Inventory (BCI).” CBE Life Sci Educ. 7 (2): 227–233.
Glass, W.G., D.H. McDermott, J.K. Lim, et al. (2006). “CCR5 deficiency increases risk of symptomatic West Nile virus infection.” J Exp Med. 203: 35-40.
Huang, Y., W.A. Paxton, S.M. Wolinsky, et al. (1996). “The role of a mutant CCR5
Biology International Vol. 47 115 Weisstein Tony Weisstein is an Associate Professor of Biology at Truman State University. He earned undergraduate degrees in mathematics at chemistry from Washington University in St. Louis in 1993 and his Ph.D. in Evolutionary and Population Biology from the same institution in 2000. Prior to his current position, he worked as a postdoctoral fellow at the University of Otago (2000-2003) and as a research associate with the BioQUEST Curriculum Consortium (2003-2004). He serves as editor for the Biological ESTEEM Project http://bioquest.org/esteem. Tony teaches courses ranging from introductory biology to an interdisciplinary bioinformatics seminar. His research interests include mathematical biology education, theoretical population genetics, and models of molecular evolution.
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Evolutionary education: an example from Russia
Andrei V. Zinoviev
Doctor Habilitated, Professor, Zoology Dept., Tver State University, Chaikovskogo pr., 70а, Tver, 170002, Russia, [email protected]
The history of evolutionary theory development is a fascinating topic. Besides providing students with an array of historical information and personalities, it teaches them a scientific perception of the world. However, it is not always clear for them how to cope with a vast amount of information on the history of evolutionary thoughts provided in numerous textbooks. There should be a stamina, which would help them to arrange the information in a logical way as well to be ready for the perception of the new one. My practice of teaching the evolution at the university shows that the effective way to achieve good results is to go through the succeeding row of personalities and their theories by addressing three important questions. 1. What is the beginning of the Universe, and Life in particular? 2. Why is the Development going on? 3. How is the Development going on? Answers to these questions in Table format help students not only keep on following the thread of evolutionary theory development through the time. They also show the completeness and peculiarities of each particular theory, coupled with philosophical world perception of their authors. They also show, that a number of critique addresses to Darwin’s theory do not have a substantial background. It is interesting to contemplate an entangled bank, clothed with many plants of many kinds, with birds singing on the bushes, with various insects flitting about, and with worms crawling through the damp earth, and to reflect that these elaborately constructed forms, so different from each other, and dependent on each other in so complex a manner, have all been produced by laws acting around us. These laws, taken in the largest sense, being Growth with Reproduction; inheritance which is almost implied by reproduction; Variability from the indirect and direct action of the external conditions of life, and from use and disuse; a Ratio of Increase so high as to lead to a Struggle for Life, and as a consequence to Natural Selection, entailing Divergence of Character and the Extinction of less-improved forms. Thus, from the war of nature, from famine and death, the most exalted object which we are capable of conceiving, namely, the production of the higher animals, directly follows. There is grandeur in this view of life, with its several powers, having been originally breathed into a few forms or into one; and that, whilst this planet has gone cycling on according to the fixed law of gravity, from so simple a beginning endless forms most beautiful and most wonderful have been, and are being, evolved. Ch. Darwin. 1859. “On the Origin of Species…” London: John Murray. Chapter XIV. P. 489- 490.
Biology International Vol. 47 117 Zinoviev Teaching the Evolutionary theory at the background. For example, certain authors university is one of the necessary criticize Darwin for not answering the components in high education of Russian second question, which was, for example, students. Earlier taught as rather dogmatic answered by Lamarck in his “Philosophie “Darwinism”, this class now provides a zoologique” (1809). The presence of so more creative and diverse material. Positive called “le pouvoir de la vie” (the from one side, the pluralism gives an complexifying force), which pushes opportunity for some students to doubt the organisms to become more complex, Darwinian Theory. Seeming freedom in moving 'up' a ladder of progress, can not be expression of personal opinion often scientifically proved, thus it was correctly substitutes a real knowledge of the topic. abandoned by Darwin. The answer to the Although the Evolutionary theory is usually first question by Darwin is even more taught among senior students, who already surprising. Often treated as atheist, he was received a considerable amount of not in reality such. The epigraph to this information in philosophy and natural article shows his agnostic background, ideal sciences, it is essential to give them a right for the scientist. idea of structure and aim of the mentioned theory. This can be done using our original Going through evolutionary theories of the approach. past, it is necessary to draw the students’ attention to the personalities of the authors. First of all, we travel through the history of Their biographies can suitably be divided Evolutionary theory. This is a fascinating into three parts, according to the topic. Besides providing students with an classification of Goethe: Schuljahre (years array of historical information and of study), Wanderjahre (years of traveling) personalities, it teaches them a scientific and Meisterjahre (years of teaching). Only perception of the world. However, it is not reaching the third stage in the life someone always clear to them how to cope with a vast becomes able to formulate substantial amount of information on the history of philosophical theory, to which the evolutionary thoughts provided in numerous Evolutionary theory belongs as a Philosophy textbooks. There should be a stamina, which of Life. Thus, someone, formulating would help them to arrange the information something of the level of the Evolutionary in a logical way as well to be ready for the theory must have a large amount of data perception of the new one. Our practice of coupled with the rich life experience. teaching the evolution at the university Students or even young scientists do not shows that the effective way to achieve good have both, in order to be good opponents in results is to go through the succeeding row criticizing theories, produced by giants of of personalities and their theories by the past. Even talented scientists, who made addressing three important questions. 1. important contributions to the Evolutionary What is the beginning of the Universe, and theory but did not have luck to live long Life in particular? 2. Why is the enough to reach the third stage (f.i. famous Development going on? 3. How is the Russian scientists C.F. Roulier and V.O. Development going on? Answers to these Kovalevsky), did not leave anything of the questions in table format help students keep level of Buffon, Lamarck, Cuvier, Darwin or on following the thread of evolutionary Vernadsky. Therefore students must be first theory development through the time. They provided with as many facts as possible, also show the completeness and peculiarities which lie in the fundament of debated of each particular theory, coupled with theory. Step-by-step study of Darwinian “On philosophical world perception of their the Origin of Species…” helps to do that in authors. The approach shows in particular, relation to the Theory of Natural Selection, that a number of critique addresses to which reveals admirable logic and factual Darwin’s theory do not have a substantial strength.
Evolutionary education: an example from Russia 118
Surfing through the chapters of the book Individual C, possessing certain useful under the guidance of University teacher, characters, has been selected by men for students soon discover, that the secret of the further breeding. The higher number and astonishing success of the Theory resides on variability of selected individuals along with the literally gigantic amount of facts, isolation speed up the process of Artificial surveyed by Darwin. He did not use dubious Selection. forces, such as the complexifying force of Lamarck, to explain the existing order of Nature. The strength of his theory is that it explains the diversity of life as the result of action of natural forces, which can be tested scientifically. The size of the book due to numerous incorporated facts often makes it hard for students to understand an amazing Fig. 2. Darwin’s theory in relation to wild species (as shown logic of the monograph. To show it is a main in Chapter 2). goal of the teacher (Zinoviev, 2005, 2009). Following the same logic as in Chapter 1,
Darwin then finds components of the similar scheme in nature. In Chapter 2 he proves the presence of variation in nature; the higher number and variability of individuals along with isolation is often linked with higher subspecific and specific diversity. The scheme is almost complete (fig. 2); only Fig. 1. Darwin’s theory in relation to domestic animals and cultivated plants. oval and arrow must be filled. What stands for the Human Will in nature? Struggle of Trying to get an idea on patterns of changing Life or Struggle for Existence, shows and coadaptations of organisms, Darwin Darwin in Chapter 3. Here he “…have starts his analysis from domestic animals called [the] principle, by which each slight and cultivated plants. This is a very variation, if useful, is preserved, by the term productive approach. First of all, humankind of Natural Selection, in order to mark its had already possessed a considerable relation to man's power of selection”. And amount of facts on this subject, which finally, he finds the cause of Struggle for extended over many centuries. Many facts Existence – Geometrical Ratio of Increase. of selective work have been documented, Thus, already in Chapter 3 Darwin fills all thus having scientific value. Most of the the positions of his logic scheme. audience, to which the Darwinian book has been addressed, has definitely had a better knowledge of domestic animals and cultivated plants. Therefore, something proved with facts from well-known field can be later transferred to the less-known subject according to the laws of logic and analogy. Fig. 3. The complete scheme of Darwin’s theory in relation In Chapter 1, entitled “Variation under to wild species (as shown in Chapter 3): SE – struggle for Domestication”, Darwin, in fact, provides us existence, GRI – geometrical ratio of increase. with a full scheme of his theory, although applicable so far to domestic organisms. If This logic in figural representation helps drawn, it appears like that shown on the students to understand the rest of the book, figure 1: descendants of individual A differ which is quite voluminous. Explaining to the from each other due to the variation, causes readers the term Natural Selection in of which were not known to Darwin. Chapter 4, discussing laws of variation in
Biology International Vol. 47 119 Zinoviev Chapter 5 and difficulties of theory in the Zinoviev, A.V. (2005). To the "Origin of following chapter (in later editions in two Species...". Tver: Tver State Univ. chapters, 6 and 7), Darwin convincingly Press. 104 p. (in Russian). shows, that most of the criticism against his theory arises due to either unprofessional Zinoviev, A.V. (2009). "On the Origin of readers (seeming difficulties) or absence of Species..." by Charles Darwin as a contemporaneous scientific data (actual, but key book for seminars on the not fatal difficulties). The rest of the book is evolutionary theory / Proceedings of simply a test of theory by different International Scientific Conference categories of facts (behavioral – Chapter 7; “Modern Aspects of Evolutionary hybridizational – Chapter 8; paleontological Theory” (On the Occasion of 200th – Chapters 9 and 10; geographical – Anniversary of Darwin’s Birthday). Chapters 11 and 12; morphological and Bryansk: Bryansk State Univ. Press. embryological – Chapter 13). 1: 38-43 (in Russian).
Andrei V. Zinoviev - The history of evolutionary theory development is a fascinating topic. Besides providing Fig. 4. Darwin’s theory in relation to sexual dimorphism: SP students with an array of – sexual partner, W – will. historical information The visualized logical scheme of Darwinian and personalities, it teaches them a scientific theory helps students to explain various perception of the world. However, it is not categories of facts by action of natural always clear for them how to cope with a forces. For example, the easily drawn vast amount of information on the history of scheme of Sexual Selection (fig. 4) explains evolutionary thoughts provided in numerous the appearance and evolution of sexual textbooks. There should be a stamina, which dimorphism. would help them to arrange the information in a logical way as well to be ready for the An amazing logic of Darwin’s book makes perception of the new one. My practice of the study of natural history more attractive. teaching the evolution at the university Knowing it, students do not see any more a shows that the effective way to achieve good number of unrelated facts, connected by results is to go through the succeeding row dubious rules. They start reading them, like of personalities and their theories by chapters of the book, in which in addition to addressing three important questions. 1. heading the content appeared. No other What is the beginning of the Universe, and theory gives such a simple instrument for Life in particular? 2. Why is the understanding the organization and structure Development going on? 3. How is the of life on the Earth. Development going on? Answers to these questions in Table format help students not References only keep on following the thread of Darwin, Ch.R., (1859). On the origin of evolutionary theory development through species by means of natural the time. They also show the completeness selection or the preservation of and peculiarities of each particular theory, favoured races in the struggle for coupled with philosophical world perception life. John Murray: London. of their authors. They also show, that a number of critique addresses to Darwin’s theory do not have a substantial background.
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Evolution in Action: Quantitative Evolutionary Biology Education
John R. Jungck
BioQUEST Curriculum Consortium, Department of Biology, 700 College Street, Beloit, WI 53511; [email protected]; http://bioquest.org
College and university courses entitled “Evolution” often send implicit, inappropriate messages about evolution. First, many courses are taught without laboratory or field components as integral to their syllabus and evaluation (Jungck, Kiser, and Stanley, 2005; Jungck, 1984). Second, many of these same courses do not engage students in the collection, analysis, and interpretation of evolutionary data. Third, many students pass such evolution courses without having acquired widely used quantitative skills such as phylogenetics, population genetics, multivariate statistics, bioinformatics, morphometrics, biomechanics, etc. Fourth, students gain little sense of the pragmatic utility of applied evolutionary research and development in the context of their everyday concerns about food, fuel, and health nor its relationship to contemporary issues in public policy on conservation, biodiversity, stem cells, genetically modified organisms, environmental remediation, bioprospecting, gene banks, privacy, genetic piracy, forensics, and drug development (Jungck and Dyke, 1985; Jungck, 1991). Evolution textbooks are data poor: despite rich descriptions of famous experimental and observational studies in evolution, most texts primarily provide litanies of conclusions rather than primary data that students can use to evaluate whether inferences claimed by authors are warranted. In order to address these problems, the Synergistic Evolutionary LEarning Consortium: Evolution in AcTION (SELECTION) was founded as a “Working Group” of the National Evolutionary Synthesis Center (NESCent); it focused on implementing applied evolutionary research in undergraduate biology education. Members of the working group included the BioQUEST Curriculum Consortium, scientific specialists, and science education researchers. Evolutionary research is engaged with many contemporary human problems in ways that are seldom included in current undergraduate biology education. Consonant with the aims of NESCent, SELECTION stressed the use of rich, complex data in such a fashion that students could: (1) explore these data with sophisticated, contemporary, and appropriate analytical tools; (2) use evolutionary analysis as a problem solving tool with practical consequences; and, (3) apply their inferences to contemporary issues of global importance.
Keywords: Evolution research-based labs; databases of primary data; open science education
Introduction same courses do not engage students in the College and university courses entitled collection, analysis, and interpretation of “Evolution” often send implicit, evolutionary data. Third, many students pass inappropriate messages about evolution. such evolution courses without having First, many courses across the nation are acquired widely used quantitative skills such taught without laboratory or field as in phylogenetics, population genetics, components as integral to their syllabus and multivariate statistics, bioinformatics, evaluation (Jungck, Kiser, and Stanley, morphometrics, biomechanics, etc. Fourth, 2005; Jungck, 1998). Second, many of these students gain little sense of the pragmatic
Biology International Vol. 47 121 Jungck utility of applied evolutionary research and each of these problems by the development development in the context of their everyday and dissemination of investigative cases concerns about food, fuel, and health nor its (Waterman and Stanley, 2008), problem relationship to contemporary issues in public spaces (Donovan, 2001; Jungck et al., policy on conservation, biodiversity, stem 2010), and strategic simulatons (Jungck and cells, genetically modified organisms, Calley, 1985; Soderberg and Price, 2003) environmental remediation, bioprospecting, that engage students in developing skills in privacy, forensics, and drug development evolutionary analysis. Our approach is to (Jungck and Dyke, 1985; Jungck, 1991). help students develop skills in the collection, Fifth, except for exposure to phylogenetic analysis, and interpretation of evolutionary trees constructed from molecular sequences, data and to discuss issues in the context of students are often screened off from empirical research by exploring the contemporary evolutionary research and, consequences of various policy decisions. thus, many of the classic experiments and/or Also, by using a more learner-centered field studies seem like “period pieces.” approach and focusing on data, skills, and problem solving, the students develop much Evolution textbooks are data poor: despite more depth to base their positions in rich descriptions of famous experimental debates. and observational studies in evolution, most texts primarily provide litanies of conclusions rather than primary data that students can use to evaluate whether inferences claimed by authors are warranted. Figure 1. Logo for the Synergistic Evolutionary LEarning Furthermore, textbooks have been shown to Consortium: Evolution in AcTION (SELECTION), a “Working Group” of the National Evolutionary Synthesis silence student questions rather than elicit Center (
Evolution in Action: quantitative evolutionary biology education 122 chemotherapeutics); prevention of Scotchmoor, Judy Leader of the Paleontology Museum “Understanding Evolution” destruction to our environment by invasive University of California website and convener of species; use of index fossils to identify - Berkeley many national symposia on energy reserves; simulation of locomotion of evolution education diverse species (living and extinct) to understand human biomechanics and Katja Schulz, University Managing editor, The Tree construct better protheses; improvement in of Arizona, of Life Web Project (ToL Now with the
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trypanosomiasis, Chagas disease, D. Energy schistosomiasis, amoebic dysentery); i. use of index fossils to identify iii. development of drug resistance energy reserves; in cancer chemotherapy as well ii. selection of microorganisms evolutionary analysis to determine capable of cleaning up oil spills; whether clinical chemotherapy iii. development of renewable, treatment will be efficacious or sustainable biofuels. nontoxic for a specific patient; E. Industry/Engineering iv. simulation of locomotion of i. Genetic Algorithms/Evolutionary diverse species (living and extinct) to or Darwinian Programming; Optimi- understand human biomechanics by zation drawing on evolutionary ii. Artificial Life morphometrics and build better iii. Robotics prostheses; iv. Biomimesis B. Agriculture and Food Production/ v. Prosthetic limbs and organs Processing: i. development of resistance to The members of the SELECTION Working extensively used biocides (antibiotics, Group had expertise in many of the areas herbicides, pesticides) and associated that we feel particularly need addressing: economic costs; health, agriculture, environment, energy, ii. improvement in the yield and historically important case studies, and quality of crops and livestock; science education. Members of the iii. identification of Vavilov centers SELECTION Working Group population of origin for crops to pinpoint sources represented three major constituencies: (1) a of genetic diversity in drought variety of institutional types: research resistance, protein yield, etc.; universities, primarily undergraduate state iv. use of highly selected strains in universities, liberal arts colleges, and soy sauce, kimchee, yoghurt, wine, community colleges; (2) diverse disciplinary beer fermentation industries to speed backgrounds: population and quantitative up production; genetics, evolutionary ecology, v. Ames testing for mutagens/ bioinformatics, metagenomics, and carcinogens in food products (e.g., phylogenetic systematics; and, (3) aflatoxin) participation in a variety of evolutionary vi. use of evolutionary ecology in education initiatives: software, books, food preservation (e.g., use competing museum exhibits, outreach programs, species to prevent potentially toxic faculty development workshops, and microbes from forming biofilms); science education research. We had C. Environmental Protection interacted with one another previously in a i. prevention of destruction to our variety of shared venues over the past ten environment by invasive species; years so we came prepared with a common ii. sustainable management of understanding of challenges in evolution national parks, preserves, and education. While much of our collaboration international heritage sites (island was through electronic communication, we biogeography and fragmentation); held three meetings at NESCent iii. use of phylogenetic profiling and headquarters, one at an annual BioQUEST metagenomics to measure biodiversity Curriculum Consortium annual Curriculum of threatened and recovering Development Workshop: “Exploratory ecosystems and remediation sites; Evolution Education” iv. preservation of endangered (
Evolution in Action: quantitative evolutionary biology education 124
Despite the obvious reference to Michael needed, but more and more the Majerus’s (1998). Melanism: Evolution in capacity to analyze highly Action, I have decided to not use controversial situations for which Kettlewell’s (1973) famous case of there is no previous modeling, is industrial melanism and the change in required (technology risks, scientific frequency of light and dark morphs of uncertainties, a multiplicity of peppered moths (even though we (Price et possible scenarios, and conflicts of al., 2003a) used peppered moths as the icons moral value). for our population genetics simulation (Source: Vincent-Antonin Lepinay EVOLVE) because of extensive recent and Verena Paravel, Demoscience, criticism of his experimental protocols and MIT, Mapping Controversies website: further research (Hopper, 2002). While we
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Figure 3: Student (Aaron Nesser, David Meltzer, and Jared Wynne, 2010) representation of the morphological variation in thirteen Galapagos finch species based upon the use of three parameters from the BIRDD database entered into the Figure 2. Composite screen shot from BIRDD statistical software package JMP. Each colored cloud of (
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chapters and countered anticipated objections in the next four chapters; the last four chapters used evolution by natural selection to explain the data naturalists had accumulated. "No one who presented an evolutionary account worked that way until Darwin," Lennox said. "His mastery of data and ability to display all of it as a consequence of evolution by natural selection let him make a compelling case where no one could before. As a result, Darwin convinced Figure 4. Student (Emma Pauly-Hubbard and Alexia a generation of scientists that there Borland, 2010) analysis of BIRDD data to examine character was an evolutionary explanation for displacement. Here they showed significant variation on different islands (above) and then they examined variation the fossil record and biogeographical when two species occurred on the same island or only on evidence." (Pitt Chronicle: different islands.
James Lennox, professor of the Thus, the ability to navigate, mine, organize history and philosophy of science in complex data sets is a basic skill of Pitt's School of Arts and Sciences, evolutionary biology which values says that Darwin triggered a lasting synthesis, hypothesis testing, multiple shift in the way naturalists present working hypotheses, testing null hypotheses, their ideas by showing how massive and visualization of heterogeneous data in amounts of data in paleontology, multidimensional space (consider, for biogeography, and morphology could example, rugged dynamic adaptive fitness all be explained by his theory. Many landscapes). There are many difficulties of Darwin's contemporaries grappled that students encounter when learning with the same questions he sought to evolutionary biology, many of them answer, but Darwin was the first to common in our culture. Ernst Mayr (1972) make a convincing case for the identified a few such as Platonistic explanatory power of evolution, universals, essentialism, and synchronic Lennox said. By the 1800s, a wealth focus on proximate causes rather than of fossil evidence challenged the long- population thinking, diachronic processes, standing idea that all species were and ultimate causes. Undoubtedly, some of created simultaneously, showing these barriers stem from the ways that instead a continuous sequence of evolution is taught in the classroom. All too origination and extinction. Plus, frequently, evolution is treated as a topic, European expeditions since the late considered in its turn and then dropped, as 16th century brought back plants and the course moves on to the next topic area. animals suggesting that species in But there is more to understanding each region were related by descent. evolutionary biology than using it to Most naturalist theories had been highlight the connections between subject presented as narratives that were not areas. Effective instruction in evolutionary convincing, Lennox said. In On the biology requires that students recognize the Origin, Darwin presented his theory of impact of evolutionary thinking on the ways natural selection in the first four
Biology International Vol. 47 127 Jungck all biologists ask and answer questions about the natural world.
Students should have the chance to consider the nature of evolutionary biology as a science. Without opportunities to use evolutionary reasoning to define and solve problems, it is difficult for students to appreciate the discipline in a meaningful way. There are, however, relatively few tools or practices that allow students to Figure 5. Over hundreds of years, Native Americans bred explore evolutionary hypotheses as corn from cobs as small as the Teosinte diploperrenis to the biologists do. Usually evolutionary models enormous cobs of contemporary Zea mays. These were and patterns are presented to students personal gifts from Hugh Iltis to the author. To read about the discovery of corn’s ancestry, consult: (Iltis,1979). without reference to the data and to the arguments on which those conclusions are Genes from the wild relative conferred based. The compilation of data and resistance to many diseases of modern corn resources for this project have focused on and were bred into seed stocks. Economic providing materials that are both broad and estimates were that billions of dollars were deep enough to support a wide range of saved by American agriculture by this student investigations. Our hope (Price et finding. al., 2003b) is that this module will simulate the design of laboratories and other Gregory (2009) lays out ten important things curricular materials that will promote a that can be learned from artificial selection deeper understanding of evolutionary and domestication; among his first his biology by emphasizing student examples for point # 1 that: “Selection Can participation in realistic evolutionary Result in Profound Changes” is corn. inquiry. Similarly, Stephen Matheson of Calvin
College uses the research literature on the (2) Illinois Corn Selection Experiment transition from teosinte to corn as
demonstrating that: “The change from Artificial selection through selective teosinte to corn happened in about a breeding is one of the most important thousand years. That's fast evolution. Apply applications of evolution to improvement in selection to a varying population, and you the human diet. Based upon archaeological get new functions, new proteins, new genes, data, estimates are that corn has been completely new organisms. Fast.” (25 selected upon for about 2,800 years October 2007 They selected teosinte...and (although a 2009 NSF report posited a date got corn. Excellent!
to twentieth century corn research.
Evolution in Action: quantitative evolutionary biology education 128
However, two other corn stories are amongst (RHP, RLP, RLP2, RHO, RLO, and some of the best examples of long term SHO. selection; namely, an experiment that ran for more than a century and the incredible Values obtained for protein in the transformation of yields in about sixty years. strains selected for oil and the values for oil obtained for the strains selected for protein each generation (1896- 2004): This file contains values obtained for protein in the strains selected for oil (IHO, ILO, etc.) and the values for oil obtained for the strains selected for protein (IHP, ILP, etc.) each generation.
All five data sets are available through the IDEALS project website (Illinois Digitalized Environment for Access to Figure 6. The data from the Illinois long-term selection Learning and Scholarship at experiments are publically available. I have made them available as an attachment to this issue as an Excel
Biology International Vol. 47 129 Jungck domestication.” In their earlier work, Wang Cytogenetics, (2) Gene Products, (3) Loci et al. (1999) posted all of their sequences (including genes), (4) Maps, (5) Metabolic Pathways, (6) Phenotypes & Mutants, (7) Probes & Molecular Markers, (8) Quantitative Trait Loci (QTLs), (9) Sequences, (10) Stocks, and (11) Variations (Polymorphisms, Alleles, etc.). The Maize Genome Browser ( Figure 7. US corn farmers increased their average yied from panzea.org>) has a similar extensive suite of about 20 bushes per acre to about six to sevens times as much tools and databases as well as a set of in a seventy year period. Image from the University of Nebraska-Lincoln (2004) ( Evolution in Action: quantitative evolutionary biology education 130 (4) Phylogeographer 1.0 is a tool for trait evolution during artificial selection. evaluating genetic and geographic With the Illinois experiments, my students interactions. (Java) The author warns became quite interested in the human side of that it is out of date, but the Java code artificial selection. Since there is such a long still worked on our machines. Buckler, period that expands way beyond any single Edward S., IV. 1999. Phylogeo- investigator’s involvement, would you feel grapher: Software for the analysis of that you were destroying the whole project if phylogeographic hypotheses. say during your involvement for a few years ( Biology International Vol. 47 131 Jungck disperse seed, and 3) cultivation of a for the seed industry and the cash crop, such as short stature application of agricultural sorghum, instead of maize, making the technology.” presence of teosinte as a weed obvious. By the best estimates, the Similarly some students are very motivated current distribution of teosinte is about by Michael Pollan’s In Defense Of Food: An half of what it was in 1900, as Eater's Manifesto (2008) critique of “Big evidenced by herbarium specimens Corn” and the dangers of high fructose corn and written accounts (Harshberger syrup, improper feeding of cattle, and 1893; Collins 1921). The factory farming that is deeply dependent disappearance of the remaining upon massive utilization of fossil fuels. populations will accelerate as more Similarly, the PBS Independent Lens’ roads are built and land use is special: King Corn (http://www.pbs.org/ intensified. … Clearly, we must independentlens/kingcorn/) by filmmakers realize that in any policy discussion Aaron Woolf, Curt Ellis and Ian Cheney, we are influencing local habitats and recent graduates of the University of Iowa as the world is being remade in human and Yale College, has also had a compelling terms to be more productive, we are appeal to many students interested in eating not thinking about the wild plants. better, knowing where their food comes (page 16) from, and avoiding the risks of developing diabetes. Yet the National Corn Growers and suggests a variety of strategies and Association’s site (http://www.ncga.com/) policies from an ecological and evolutionary cites goals that seem as though none of their perspective of which few have been actively issues are relevant: pursued. It is helpful for students to contrast that approach with that of van Dusen (2000) • Increased efficiency of public and who presents a more industrial and private corn breeding programs economic perspective for addressing these • Quicker delivery of new, beneficial same issues under the rubrick of biosafety traits and biotechnology. • Enhancement of drought tolerance and pest resistance traits in corn “Facing the issues of path dependency • New efficiencies to be gained in that regulation creates, the goal of utilization inputs such as nitrogen biosafety is to protect the safety of the • Attraction of quality students and population and the environment while researchers to plant genomic and fomenting the development of new genetic fields technologies. The corresponding • Creation of a model to complete dangers for misguided policy are both other major crop genome sequences the stifling of technological development through the Nonetheless many of our Midwestern discouragement of investment and students from farming backgrounds also research, and the possible have sympathy for farmers who react with environmental and human frustration as the one below (Blake Hurst) consequences, which have a strong did: dynamic component (one popular metaphor is “letting the genie out of He was a businessman, and I’m sure the bottle”). Equally important is to spends his days with spreadsheets, recognize that the lack of a regulatory projections, and marketing studies. He framework can endanger human hasn’t used a slide rule in his career health and natural resources, as well and wouldn’t make projections with as the present and future possibilities Evolution in Action: quantitative evolutionary biology education 132 tea leaves or soothsayers. He does not (3) Other modules blame witchcraft for a bad quarter, or expect the factory that makes his Members of the SELECTION Working product to use steam power instead of Group developed a variety of other data rich electricity, or horses and wagons to evolutionary education materials. Kristin deliver his products instead of trucks Jenkins and Kirsten Fisher, both of and trains. But he expects me to farm NESCent, developed a “problem space” that like my grandfather, and not employs bioinformatics tools to analyze “the incidentally, I suppose, to live like evolutionary relationships of genes involved him as well. He thinks farmers are too in desiccation tolerance, gene expression stupid to farm sustainably, too cruel to data for desiccation sensitive and tolerant treat their animals well, and too plants, data and tools for exploring of careless to worry about their geographical distribution of a dessication communities, their health, and their tolerant and related dessication sensitive families. I would not presume to species, and tools for understanding criticize his car, or the size of his information entropy and the principle of house, or the way he runs his business. maximum entropy used in an ecological But he is an expert about me, on the niche modeling application (Oliver,Tuba, strength of one book, and is sharing and Mischler, 2000; Rascia, and La Rocca, that expertise with captive audiences 2005). The materials in the problem space every time he gets the chance. are ideal for exploring agricultural Enough, enough, enough. (Source: applications. Blake Hurst, The Omnivore’s Delusion: Against the Agri- • To use phylogentic analysis of genes intellectuals, American Enter-prise to identify families of genes common Institute for Public Policy Research between evolutionarily basal ( Biology International Vol. 47 133 Jungck agricultural plants in drylands or areas at situation and fail to engage students in risk of increased desertification.” evolutionary problem solving. The rhetorical devices of data anthropomorphum: results Claudia Neuhauser, Vice Chancellor of the show, research suggests, data indicate, etc., University of Minnesota-Rochester, used a are imperialistic power moves that silence database of single nucleotide poly- students and definitely do not invite them to morphisms (SNPs) in different pathogeneic interpret data on their own and test the isolates of Salmonella enterica warrants of such inferences. The raw data ( Evolution in Action: quantitative evolutionary biology education 134 Buckler, E. S., IV, M. M. 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Jungck, John R., and John N. Calley. (1985). “Meta-representation: An Introduction.” “Strategic Simulations and Post-Socratic J. Mathematical Behavior 19 (3): 385- Pedagogy: Constructing Computer 398. Software to Develop Long-term Inference through Experimental Donovan, S., and Greene, K. (2005). Inquiry.” American Biology Teacher 47 “Ramping up to Biology Student (1): 11-15. Workbench: A multi-stage approach to bioinformatics education.” Bioscene— Jungck, John R., and Charles Dyke. (1985). Journal of College Science Teaching “Evolution, Economics and Education: 31(1): 3-11. Understanding the Consequences of Natural Selection in Health and Donovan, Samuel. (2005). “Tree Thinking Disease.” American Biology Teacher 47 and Reasoning about Change Over Deep (3): 138-141. Time.” In Joel Cracraft and Rodger W. Bybee, editors, Evolutionary Science Jungck, John R., Sam Donovan, and John and Society: Educating a New Greenler, (2003). “One Cell, Three Generation. 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Price, Frank, Sam Donovan, Jim Stewart, Lia, Verónica V., Viviana A. Confalonieri, and John R. Jungck. (2003b). “BIRDD Norma Ratto, Julián A. Cámara (Beagle Investigation Returns with Hernández, Ana M. Miante Alzogaray, Darwinian Data): Darwin Finch Data Lidia Poggio, and Terence A Brown. Resource.” In John R. Jungck, editor, (2007). “Microsatellite typing of ancient The BioQUEST Library VI. Academic maize: insights into the history of Press: San Diego, California. agriculture in southern South America.” Proc. R. Soc. B 274 (1609): 545-554. Rascia, N, La Rocca, N. (2005). “Resurrection Plants: The Puzzle of Majerus, Michael E. N. (1998). Melanism: Surviving Extreme Vegetative Evolution in Action. Oxford University Desiccation.” Critical Reviews in Plant Press: London, U.K. Sciences 24: 209-225. Mayr, Ernst. (1972). “The Nature of the Ross-Ibarra, Jeffrey, Maud Tenaillon, and Darwinian Revolution.” Science 176 Brandon S. Gaut. (2009). “Historical (4038): 981-989. 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Garrison. (1997). “Teosinte in “An examination of problem-based Mexico: Personal Retrospective and teaching and learning in population Assessment.” In J. A. Serratos, M. C. genetics and evolution using EVOLVE, Wilcox, and F. Castillo, editors. Gene a computer simulation.” International Flow Among Maize Landraces, Journal of Science Education 25 (1): 35- Improved Maize Varieties, and Teosinte: 55 Implications for Transgenic Maize, CIMMYT: Mexico, pages 10-17. van Dusen, M. E. (2000). “Issues in the Release of Transgenic Crops in Wright, Stephen I., Irie Vroh Bi, Steve G. Developing Countries: The Mexican Schroeder, Masanori Yamasaki, John F. Case Study. In William H. Lesser, Doebley, Michael D. McMullen, and editor.” Transitions in Agbiotech: Brandon S. Gaut. (2005). “The Effects Economics of Strategy and Policy, of Artificial Selection on the Maize PFood Marketing Policy Center, Genome.” Science 308 (5726): 1310 – Department of Agricultural and 1314. Resource Economics, University of Connecticut, and the Department of See downloadable file: “Evolution Resource Economics, University of Education Bibliography” at site: Massachusetts, Amherst, pages 359-374. http://www.bioquest.org/evolution van Etten, Jacob, and Robert J. Hijmans. Acknowledgements (2010). “A Geospatial Modeling Approach Integrating Archaeobotany Funding for this project was provided in part and Genetics to Trace the Origin and by several NSF grants: BEDROCK Dispersal of Domesticated Plants.” (#0127498), BIRDD (#9950740), as well as PLoS ONE 5 (8): e12060. support from AAAS, HHMI, NIMBioS, doi:10.1371/journal.pone.0012060 NESCent, and the Division of Instruction Technology at the University of Wisconsin- Vigouroux, Y., M. McMullen, C. T. Madison in the form of an Instructional Hittinger, K. Houchins, L. Schulz, S. Technology Grant. Additional support was Kresovich, Y. Matsuoka, and J. provided by the Educational Research and Doebley. (2002). “Identifying genes of Development Centers Program (PR/Award agronomic importance in maize by Number R305A60007), as administered by screening microsatellites for evidence of the Office of Educational Research and selection during domestication.” Improvement, U.S. Department of Proceedings of the National Academy of Education, and by the Wisconsin Center for Sciences, USA 99: 9650–9655. Education Research, School of Education, University of Wisconsin-Madison. Wang, Rong-Lin, Adrian Stec, Jody Hey, Additional support was provided by Beloit Lewis Lukens, and John Doebley. College and Hamilton College. (1999). “The limits of selection during maize domestication.” Nature 398: 236- The author particularly expresses his 238. appreciation to all of the members of the SELECTION Working Group identified in Waterman, M. and E. Stanley. (2008). Table 1 as well as the staff of the National Biological Inquiry: A Workbook of Evolutionary Synthesis Center Investigative Cases. 2nd edition with Evolution in Action: quantitative evolutionary biology education 138 Darwin and Dispersal Richard C. Winkworth University of the South Pacific, School of Biological and Chemical Sciences, Laucala Bay Campus, Suva, Fiji, [email protected] For Darwin the only possible explanation for the disjunct distributions of many southern hemisphere plant groups was dispersal. To the best of his knowledge the landmasses were static and so the only way for an organism to cross between continents was long distance dispersal. Widely accepted for a century, dispersal was quickly relegated to the rank of irrelevant noise with the recognition of plate tectonics in the1960s. Vicariance – the idea that organisms simply moved around with the landmasses they inhabited – became the dominant explanation. However, vicariance has recently been challenged by evidence from molecular phylogenetic studies. Genetic data provides compelling evidence that the ancestors of many transoceanic disjuncts jumped vast marine barriers. Long distance dispersal is again in fashion. In this paper I use southern hemisphere biogeography to highlight how genetic data have helped to lead a shift in biogeograpic thinking as well as some of the other insights molecular data has provided about transoceanic dispersal. Introduction year expedition (1839-1843) to chart the The British Admiralty conducted numerous Antarctic coastline. In addition to his expeditions and surveys during the 19th medical duties Hooker made collections and century. In most cases one or more scientists observations on the plants and algae accompanied these voyages to conduct encountered during the voyage (Desmond, experiments, as well as make observations 1999). On his return to England Hooker and collections. Perhaps the most famous compiled three volumes documenting his scientific voyage was that of Charles Darwin journey – Flora Antarctica (1844), Flora who traveled as a privately funded passenger Novae-Zelandiae (1853) and Flora aboard the HMS Beagle. Over the nearly Tasmaniae (1859). Hooker would also five years (1831-1836) of the voyage become a close friend and colleague of Darwin amassed an extensive collection of Darwin's (Freeman, 1978). biological specimens and notebooks filled with observations – information he would Our story really begins with Hooker’s Flora later use as the basis of “On the Origin of Novae-Zelandiae (1853). In addition to Species.” Among the many others to cataloguing and describing his New Zealand complete similar voyages was Joseph collections, Hooker used this volume to Hooker. Hooker served as the Assistant document and discuss his observations on Surgeon aboard the HMS Erebus, which the floristic links between Australia, New together with the HMS Terror, made a four- Zealand, and southern South America. Biology International Vol. 47 139 Winkworth Indeed Hooker was so impressed by the differed more profoundly. While certainly links between southern hemisphere aware of land bridges Darwin seems to have landmasses he placed the patterns been less than convinced. In a letter to significance on a par with the floristic Hooker he wrote, “it shocks my philosophy similarity of northern hemisphere temperate to create land, without some other & floras (Hooker, 1853). However, not content independent evidence.” In the absence of to simply document the pattern Hooker also direct physical evidence for land bridges offered an explanation – these southern Darwin considered trans-oceanic long connections were the result of common distance dispersal between widely separated ancestry. Specifically, the plant groups now landmasses a much more likely explanation shared by disjunct southern hemisphere (Fig. 1B). In contrast to Hooker’s land landmasses had originally been part of a bridge hypothesis dispersal explanations single, widespread assemblage that was imply that the similarities result from the subdivided by geological or climatic events. mixing of distinct floristic components. Although seemingly straightforward this Darwin’s preference for dispersal was based explanation presents a problem. During the on considerable personal research. He had 19th century (and for much of the 20th as made extensive comparisons of species lists well) the orthodox view was that the earth for islands and the nearby continents with was static – the position of the landmasses the goal of identifying dispersal patterns. had been stable over geological time. So Perhaps more importantly Darwin also made how could there have been a single flora if mechanistic studies. In particular examining the landmasses were not connected? The the potential for propagules to survive solution was a series of now submerged transport in seawater and documenting terrestrial connections. These so called “land various animal mediated mechanisms. bridges” provided the links necessary for a Importantly, these studies helped convince single flora to spread across the southern Darwin that dispersal was capable of hemisphere (Fig. 1A). moving plants over very long distances. Darwin was so intrigued by dispersal and its implications for species distributions that he devoted two chapters of “On the Origin of Species” to the subject (Darwin, 1859). The rise of vicariance For little over a century the views typified Fig. 1. Maps illustrating three different explanations for floristic links between Australia, New Zealand, and southern by Darwin and Hooker formed the basis of South America. A. Land bridges. Light shading indicates competing traditions. On one hand location of hypothetical, terrestrial connections that allowed researchers who favored dispersal attempted the spread of a single flora across the southern hemisphere. B. Dispersal. Arrows indicate dispersal routes between to identify so-called “centres of origin” and landmasses. C. Vicariance. Paleogeographic reconstruction dispersal routes away from them. On the of Gondwana (approximately 90 mya) with the sequence of break-up events marked. 1, isolation of New Zealand about other, those who preferred geographic and 80 mya; 2, isolation of Australia about 45-50 mya; 3, climatic explanations used shared separation of Antarctica and southern South America about distribution patterns to support their 30–28 mya (C. from Dawson and Winkworth, 2008). Abbreviations: ANT, Antarctica; AUS, Australia; SSA, viewpoint. However, a radical shift in sourthern South America; NC, New Caledonia; NG, New geological theory during the late 1960’s led Guinea; NZL, New Zealand. to a revolution in biogeography. Specifically, geologists realized that the What did Darwin think of his friend’s continents were not static. Instead plate explanation for southern hemisphere floristic tectonics caused the continents to move links? Although both Darwin and Hooker relative to one another. The idea was not were fascinated by geographical distribution new; Alfred Wegener had made a similar patterns their explanations could not have suggestion some 50 years earlier (Wegener, Darwin and dispersal 140 1968) but without sufficient evidence the branching patterns in an evolutionary tree idea was largely ignored by mainstream for a shared group would match the pattern geology. Biogeographers quickly realised of geological break up. So, if vicariance that tectonics removed the need to invoke explains southern hemisphere biogeography hypothetical land bridges. It was we expect species from each landmass to immediately obvious that plate tectonic form monophyletic groups and the processes were on a scale large enough to Australian and South American clades to be simultaneously influence the geographical more closely related to one another than distributions of multiple groups. So-called either is to the New Zealand clade. The vicariance hypotheses, based on the tectonic second prediction involves the timing of break up of ancient supercontinents, quickly events. Again assuming that organisms are gained popularity with dispersal falling from passive travelers we expect the timing of favour (Nelson and Platnick, 1981; branching events to correspond to those of Humphries and Parenti, 1999). Gondwanan break up (Fig. 2A). Therefore the split between the Australian and South So how does vicariance explain patterns of American clades would be approximately southern hemisphere biogeography? To 45-50 my old with the New Zealand lineage answer this we need to consider the final having diverged approximately 80 mya. stages in the break up of the Gondwanan supercontinent. Around 140 million years ago (mya) Gondwana consisted of Antarctica, Australia, New Zealand, and South America (Fig. 1C). New Zealand was the first to drift away. A large fragment containing both New Zealand and New Caledonia began to move gradually out into Fig. 2. Testing the predictions of vicariance models. A. The vicariance explanation holds if the patterns and timing of the southwest Pacific Ocean around 80 mya. branching events in the organismal phylogeny (narrow, black This movement led to the formation of the line) matches those predicted by the geological break up scenario (wide, grey lines). B. Molecular data for southern Tasman Sea, an event that effectively hemisphere plant groups often suggest a pattern of isolated the terrestrial biota of New Zealand organismal relationships and timing of divergence event that from that of the rest of Gondwana. In do not match the predictions of vicariance (e.g., NZL and AUS are most closely related and all the divergence events contrast, the links between Australia and post-date the geological break up). This type of pattern is South America remained intact until 50-45 better explained by dispersal (modified from Donoghue and mya when Australia separated from Moore, 2003). Antarctica. As with New Zealand the widening of the South Tasman Sea isolated The shift to dispersal the biota of Australia from those of For vicariance biogeographers the Antarctica and South America. The final observation of shared distributions provided stage of Gondwanan break up was a “test” of vicariance hypotheses. In their separation of Antarctica and South America. view “random” dispersal could not have These two landmasses were isolated 30-28 produced shared patterns of distribution mya by the opening of the Drake Passage (Morrone and Crisci, 1995). However, until (Veevers et al., 1991; McLoughlin, 2001). recently it was difficult to fully evaluate the predictions of vicariance. Perhaps most Vicariance scenarios based on this sequence critically it was not possible to estimate the of geological events make specific age of branching events. Over the last two predictions about evolutionary relationships decades advances in molecular in plant groups shared by Australia, New phylogenetics have provided a set tools that Zealand, and South America. First, since make vicariance models readily testable. vicariance assumes that organisms simply Using DNA sequence information it is now “go along for the ride” we expect that the possible to investigate both the pattern and Biology International Vol. 47 141 Winkworth timing of diversification within a group of (e.g., Bellamy et al., 1990). That is, the organisms. isolation of New Zealand allowed plants and animals with direct Gondwanan ancestry to Molecular tools are being applied to an ever- survive virtually unchanged. But new growing number of southern hemisphere molecular data indicate that the New plant groups – often with striking results. In Zealand flora has not been static. There have many of the examples studied neither the been profound changes over the last 80 pattern nor the timing of the branching million years – numerous lineages have events is consistent with the predictions of arrived by dispersal while for others New vicariance. Instead it is common to find that Zealand has been the start of their journey the Australian and New Zealand or New (e.g., Winkworth et al., 2002; McGlone Zealand and South American lineages are 2005). But this shift towards dispersal goes most closely related to one another (e.g., beyond the southern hemisphere. Globally Linder and Crisp, 1995; Winkworth et al., there has been a realisation that dispersal has 2002) and that divergence times fall within been critical for shaping geographical the last 20 my (e.g., Winkworth et al., 2002). distribution (e.g., de Queiroz, 2005). In These results are clearly more consistent many cases molecular analyses indicate the with recent dispersal than with Gondwanan lineages are simply too young for their vicariance (Fig. 2B). Beyond distinguishing distribution to have been influenced by plate dispersal and vicariance molecular data have tectonics and that current distribution also highlighted previously unrecognised patterns are better explained by dispersal. A complexity in biogeographic patterns. For classic example appears to be plant groups example, it had been assumed that shared by Africa and South America. Recent circumpolar currents would ensure eastward molecular data confirms that for over 100 dispersal (e.g., Raven, 1973). However, groups this disjunction is the result of molecular studies indicate that these large- dispersal (Renner, 2004). scale circulation systems do not strictly limited dispersal direction in the southern Biogeography has come almost full circle. hemisphere. Instead, dispersal routes and Having all but discarded dispersal as an directions differ between groups (e.g., explanation in the 1970’s, new molecular Winkworth et al., 2002; Sanmartín et al. data have led a dramatic turn around – the 2007). Even the classic examples of general importance of dispersal processes in Gondwanan relicts are not immune to biogeography is now widely accepted. But dispersal. For example, although the fossil beyond this biogeography is now beginning record places Nothofagus in Gondwana prior to look more closely at the complexity in an to break-up molecular analyses indicate a attempt to better understand underlying close relationship between the Australian mechanisms. This, I think, would have and New Zealand species. It seems that fascinated Darwin. while vicariance shaped the oldest parts of the Nothofagus tree dispersal has recently reshaped these relationships (Cook and References Crisp, 2005; Knapp et al., 2005). Bellamy, D.J., B. Spingett, P. Hayden. (1990). Moa’s ark: The voyage of It now seems clear that for many southern New Zealand. Viking: Auckland. hemisphere plant groups dispersal has been important role for shaping contemporary Cook, L.G., M.D. Crisp. (2005). “Not so distribution patterns. This finding has ancient: the extant crown group of particularly profound implications for New Nothofagus represents a post- Zealand. Textbooks and the popular media Gondwanan radiation.” Proc R Soc have been dominated by the idea that New Biol Sci. 272: 2535–2544. Zealand was a refuge for Gondwanan relicts Darwin and dispersal 142 de Queiroz A. (2005). “The resurrection of Knapp, M., K. Stöckler, D. 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Richard Winkworth is a lecturer in the Faculty of Science and Technology at the University of the South Pacific (USP) where he teaches undergraduate courses in plant and quantitative biology. Richard is fascinated by the geographic distributions of plants and animals, and more especially by the processes that have acted to shape distribution patterns. He is particularly interested in patterns of diversity in the Southern Hemisphere and on oceanic islands. At USP he heads the molecular systematics laboratory and supervises postgraduate students studying the Pacific biota. Darwin and dispersal 144 Biology International The Official Journal of the International Union of Biological Sciences Biology International, the biannual peer-reviewed journal of the International Union of Biological Sciences, exists to advance scholarly discourse about the research, theory, and practice of research biologists and biology educators from around the world. 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