Definitions and Levels Of

Total Page:16

File Type:pdf, Size:1020Kb

Definitions and Levels Of Definitions and Levels of Although understandable given their strictly enlargement resulted in the capacity to Analysis biological interpretation of exaptations, this practice religion, and (c) that religious approach is problematic because the authors practices function to assuage the fear of death sought to apply their standards of evidence to (which would itself be required to meet the Theodore Beauchaine the list of exaptations proposed by Gould evidentiary standards of a spandrel). Al- State University of New York (1991), namely language, religion, principles though the first two of these conjectures may at Stony Brook of commerce, warfare, reading, writing, and be true, they can at best be confirmed only at the fine arts. All of the items on this list are the pseudoempirical level. Gould (1991) rec- Although Buss, Haselton Shackelford, psychological phenomena borne of a ognized this and suggested that the term Bleske, and Wakefield (1998) presented a structural complexity (i.e.. the human brain) aptation be applied to cases where a lack of topic that deserves mainstream attention in that is not well understood and that was not historical evidence precludes the determina- psychology, I am concerned about their arti- sufficiently considered by the authors. Here tion of whether a characteristic is an adapta- cle on several grounds. My main concern is again. Buss et al. may have misinterpreted tion or an exaptation. Furthermore, confirm- with their interpretations of Gould’s (1987 Gould, who did not use human brain size ing or disconfirming the third conjecture is 1991, 1997) writings. Buss et al. suggested merely as an "example of an exaptation" (p. far more difficult than establishing the utility that Gould (1991) was inconsistent in his 539), as the authors stated. Rather, Gould of female orgasm as a sperm transport usage of the term exaptation, and that his suggested that the human brain, by virtue of mechanism, because the functional level of “stated definitions seem to require that these both complexity and flexibility, is “the best analysis is psychological, not structural. effects and culturally useful features available case for predominant exaptation-- All of the proposed exaptations listed (exaptations) must contribute to fitness and in other words, for a near certainty that by Gould (1991), because they are specified have specifiable biological functions [italics exaptations must greatly exceed adaptations at the psychological level, are similarly pre- added] to qualify as exaptations” (p.541). Yet in number and importance” (p. 55). Gould cluded from meeting the strict evidentiary nowhere in Gould’s (1987 1991, 1997) offered the practice of religion as an example standards set forth by Buss et al. (1998). Yet, writings did he suggest that the function and suggested that our enlarged brains force it would be unfortunate indeed if psycholo- performed by an exaptation needs to be us to confront our own mortality. Because it gists, in an effort to meet such standards, biological. As Buss et al. reported, Gould is quite unlikely that brain enlargement were to reject Gould's distinctions and con- (1991) offered two definitions of exaptation: evolved to serve this end, the practice of tinue in adaptationist practices. We should "a feature, now useful to an organism, that religion performs an exapted function by recognize the error in logic of inferring evo- did not arise as an adaptation for its present moderating, through a variety of themes, our lutionary cause from current consequence, role, but was subsequently coopted for its evolutionarily functional fear of death. Thus, whether or not we can empirically demon- current function" (p.43) and "features that recognition of our own mortality is a strate the existence of psychological exapta- now enhance fitness, but were not built by spandrel, and the practice of religion is an tions. natural selection for their current role" (p.47). exaptation. Thus, although exaptations always provide a Moreover, it is a priori unlikely that REFERENCES current function, that function need not be such complex psychological phenomena can biological. In fact, Gould’s (1991) thesis is meet the standards of evidence proposed by Buss, D. M., Haselton, M. G., Shackelford. geared toward exapted functions performed Buss et al. (1998). Specifically, they suggest- T. K., Bleske, A. L., & Wakefield, J. C. by the brain to serve psychological rather ed that evidence of special design for a hy- (1998). Adaptations, exaptations, and than biological functions. pothesized function be demonstrated before spandrels. American Psychologist, 53, 533- Additionally, Buss et al. (1998) concluding that any structure or behavior is 548. suggested that Gould (1991) used the term adaptive. As an example, they presented the Gould, S. J. (1987). Freudian slip. Natural exaptation “to cover novel but functionless hypothesis that female orgasm serves the History, 96, 14-21. uses or consequences of existing adaptive function of facilitating sperm trans- Gould, S. J. (1991). Exaptation: A crucial characteristics" (p. 539) My reading of Gould port, for which evidence is reportedly lack- tool for an evolutionary psychology. (1987, 1991, 1997) suggests otherwise: ing. It is thus concluded that female orgasm Journal of Social Issues, 47, 43-65. Structures or characteristics for which there does not serve the hypothesized adaptive Gould, S. J. (1997). The exaptive excellence are no identifiable functions, either current or function. Although instructive, this example of spandrels as a term and prototype. historical, are always spandrels. Thus, the trivializes the difficulty of falsifying, at the Proceedings of the National Academy of term spandrel subsumes what Buss et al. phenotypic level, hypotheses about exapted Sciences, 94, 10750-10755. referred to as functionless by-products. When psychological functions, such as the practice a spandrel is coopted (exapted) for a function, of religion. There are at least two reasons for it becomes an exaptation; there is no need to this. First, as outlined by Buss et al., exapta- Correspondence concerning this comment differentiate between spandrels and tions "carry the additional evidentiary should be addressed to Theodore Beauchaine, functionless byproducts. Ironically, Gould burdens of documenting both later co-opted Department of Psychology, State University (1991) coined the terms exaptation and functionality, and a distinctive original of New York, Stony Brook, NY 11794-2500. spandrel to avoid this sort of confusion. adaptational functionality" (p. 546). Thus, to Electronic mail may be sent to Additionally, although Buss et al. confirm the exapted function of religious [email protected]. (1998) sought to outline the usefulness of the practice, one would be required to terms adaptation, exaptation, and spandrel for demonstrate (a) that enlarged brains were the science of psychology, most of their naturally selected for reasons independent of discussion was restricted to structural rather religious practice, (b) that such brain than psychological levels of analysis. June 1999 • American Psychologist 439-440 .
Recommended publications
  • 1 "Principles of Phylogenetics: Ecology
    "PRINCIPLES OF PHYLOGENETICS: ECOLOGY AND EVOLUTION" Integrative Biology 200 Spring 2016 University of California, Berkeley D.D. Ackerly March 7, 2016. Phylogenetics and Adaptation What is to be explained? • What is the evolutionary history of trait x that we see in a lineage (homology) or multiple lineages (homoplasy) - adaptations as states • Is natural selection the primary evolutionary process leading to the ‘fit’ of organisms to their environment? • Why are some traits more prevalent (occur in more species): number of origins vs. trait- dependent diversification rates (speciation – extinction) Some high points in the history of the adaptation debate: 1950s • Modern Synthesis of Genetics (Dobzhansky), Paleontology (Simpson) and Systematics (Mayr, Grant) 1960s • Rise of evolutionary ecology – synthesis of ecology with strong adaptationism via optimality theory, with little to no history; leads to Sociobiology in the 70s • Appearance of cladistics (Hennig) 1972 • Eldredge and Gould – punctuated equilibrium – argue that Modern Synthesis can’t explain pervasive observation of stasis in fossil record; Gould focuses on development and constraint as explanations, Eldredge more on ecology and importance of migration to minimize selective pressure 1979 • Gould and Lewontin – Spandrels – general critique of adaptationist program and call for rigorous hypothesis testing of alternatives for the ‘fit’ between organism and environment 1980’s • Debate on whether macroevolution can be explained by microevolutionary processes • Comparative methods
    [Show full text]
  • Testing Darwin's Hypothesis About The
    vol. 193, no. 2 the american naturalist february 2019 Natural History Note Testing Darwin’s Hypothesis about the Wonderful Venus Flytrap: Marginal Spikes Form a “Horrid q1 Prison” for Moderate-Sized Insect Prey Alexander L. Davis,1 Matthew H. Babb,1 Matthew C. Lowe,1 Adam T. Yeh,1 Brandon T. Lee,1 and Christopher H. Martin1,2,* 1. Department of Biology, University of North Carolina, Chapel Hill, North Carolina 27599; 2. Department of Integrative Biology and Museum of Vertebrate Zoology, University of California, Berkeley, California 94720 Submitted May 8, 2018; Accepted September 24, 2018; Electronically published Month XX, 2018 Dryad data: https://dx.doi.org/10.5061/dryad.h8401kn. abstract: Botanical carnivory is a novel feeding strategy associated providing new ecological opportunities (Wainwright et al. with numerous physiological and morphological adaptations. How- 2012; Maia et al. 2013; Martin and Wainwright 2013; Stroud ever, the benefits of these novel carnivorous traits are rarely tested. and Losos 2016). Despite the importance of these traits, our We used field observations, lab experiments, and a seminatural ex- understanding of the adaptive value of novel structures is of- periment to test prey capture function of the marginal spikes on snap ten assumed and rarely directly tested. Frequently, this is be- traps of the Venus flytrap (Dionaea muscipula). Our field and labora- cause it is difficult or impossible to manipulate the trait with- fi tory results suggested inef cient capture success: fewer than one in four out impairing organismal function in an unintended way; prey encounters led to prey capture. Removing the marginal spikes de- creased the rate of prey capture success for moderate-sized cricket prey however, many carnivorous plant traits do not present this by 90%, but this effect disappeared for larger prey.
    [Show full text]
  • Exapting Exaptation
    Spotlight Exapting exaptation 1 2 3 3 Greger Larson , Philip A. Stephens , Jamshid J. Tehrani , and Robert H. Layton 1 Durham Evolution and Ancient DNA, Department of Archaeology, Durham University, South Road, Durham, DH1 3LE, UK 2 School of Biological and Biomedical Sciences, Durham University, South Road, Durham, DH1 3LE, UK 3 Department of Anthropology, Durham University, South Road, Durham, DH1 3LE, UK The term exaptation was introduced to encourage biol- As a result, all adaptations can also be said to be exapta- ogists to consider alternatives to adaptation to explain tions, thus rendering the term redundant [4]. the origins of traits. Here, we discuss why exaptation has proved more successful in technological than biological Technology and the exaptation of exaptation contexts, and propose a revised definition of exaptation Despite failing to catch on in evolutionary biology, exapta- applicable to both genetic and cultural evolution. tion has been adopted with considerable success in studies of the history of technology [5]. Technological innovations frequently involve the use of a process or artefact in a new The rise and fall of biological exaptation context [6]. A classic example is microwave radiation, Last year marked a decade since the death of Stephen Jay which was originally used in the radar magnetron to Gould, and 30 years since the publication of one of his most intercept and reflect off target objects, and was subse- provocative challenges to orthodox evolutionary theory quently exapted as a means to heat food. Similarly, tech- [1,2]. Concerned about a perceived lack of rigour, Gould, nologies that were initially developed as part of NASA’s together with Elizabeth Vrba, introduced a vocabulary space research program were later exploited for new com- intended to undermine the primacy of adaptation for mercial uses.
    [Show full text]
  • The Spandrels of Self-Deception: Prospects for a Biological Theory of a Mental Phenomenon
    The Spandrels of Self-Deception: Prospects for a Biological Theory of a Mental Phenomenon D. S. Neil Van Leeuwen Self-deception is so undeniable a fact of human life that if anyone tried to deny its existence, the proper response would be to accuse this person of it. —Allen Wood1 1. Introduction to the Problems Even prior to a characterization of self-deception, it’s easy to see that it’s widespread. This is puzzling, because self-deception seems paradoxical. Here are three apparent problems. First, self-deception seems to involve a conceptual contradiction; in order to deceive, one must believe the contrary of the deception one is perpetrating, but if one believes the contrary, it seems impossible for that very self to believe the deception.2 Second, a view of the mind has become widely accepted that makes rationality constitutive and exhaustive of the mental; this is the interpretive view of the mental put forth by Donald Davidson and followers.3 According to this view, the idea of attributing irrational beliefs to agents makes little sense, for we cannot make sense of what someone’s beliefs are unless they are rational. But self-deception is highly irrational.4 Third, a brief survey of other cognitive mechanisms (such as vision) reveals that most are well suited for giving us reliable information about ourselves and our environment. Self- deception, however, undermines knowledge of ourselves and the world. If having good information brings fitness benefits to organisms, how is it that self-deception was not weeded out by natural selection? Otherwise put, why does self-deception exist? (For convenience, I shall refer to these as puzzles 1, 2, and 3.) Puzzles such as these make self-deception an intriguing explanatory target.
    [Show full text]
  • Evolution # 6 Tempoandmode
    Bio 1B Lecture Outline (please print and bring along) Fall, 2008 B.D. Mishler, Dept. of Integrative Biology 2-6810, [email protected] Evolution lecture #6 -- Tempo and Mode in Macroevolution -- Nov. 14th, 2008 Reading: pp. 521-531 (ch. 25) 8th ed. pp. 480-488 (ch. 24) 7th ed. • Summary of topics • Define and contrast adaptation and exaptation • Give examples of how adaptive radiations lead to diversity within an evolutionary lineage • Give examples of how convergent evolution shows the action of selection on organisms that are not closely related but have a shared way of life • Contrast punctuated equilibria and gradualism • Describe the features of developmental changes that can lead to evolution ("evo-devo") • Define macroevolution • Adaptation Adaptation: Based on the observation that organism matches environment closely. Darwin & many Darwinians thought that all structures must be adaptive for something. But, this has come under severe challenge in recent years. Not all structures and functions are adaptive. Some matches between organism and environment are accidental, or the causality is reverse (i.e., the structure came first, function much later). • By definition, an adaptation in a formal sense requires fulfillment of four different tests: Engineering. Structure must indeed function in hypothesized sense. Heritability. Differences between organisms must be passed on to offspring. Natural Selection. Difference in fitness must occur because of differences in the hypothesized adaptation. Phylogeny. Hypothesized adaptive state must have evolved in the context of the hypothesized cause. Think in terms of problem (e.g., environmental change) and solution (adaptation). Requires correct phylogenetic polarity (i.e., correct sequence of events on a cladogram).
    [Show full text]
  • The Spandrels of San Marco and the Panglossian Paradigm: a Critique of the Adaptationist Programme
    The Spandrels of San Marco and the Panglossian Paradigm: A Critique of the Adaptationist Programme. (Excerpted1 by W. M. Schaffer) Stephen Jay Gould and Richard C. Lewontin. 1979. Proc. Roy. Soc. London, Ser. B, 505: 581-598. An adaptationist programme has dominated evolutionary thought in England and the United States during the past forty years. It is based on faith in the power of natural selection as an optimizing agent. It proceeds by breaking an organism into unitary "traits" and proposing an adaptive story for each considered separately. Trade-offs among competing selective demands exert the only brake upon perfection; non-optimality is thereby rendered as a result of adaptation as well. We criticize this approach and attempt to reassert a competing notion (long popular in continental Europe) that organisms must be analyzed as integrated wholes, with Baupläne[2] so constrained by phyletic heritage, pathways of development, and general architecture that the constraints them- selves become more interesting and more important in delimiting pathways of change than the selective force that may mediate change when it occurs. We fault the adaptationist programme for its failure to distinguish current utility from reasons for origin (male tyrannosaurs may have used their diminutive front legs to titillate female partners, but this will not explain why they got so small); for its unwillingness to consider alternatives to adaptive stories; for its reliance upon plau- sibility alone as a criterion for accepting speculative tales; and for its failure to consider adequately such competing themes as random fixation of alleles, production of non-adaptive structures by developmental correlation with selected features … , the separability of adaptation and selection, multiple adaptive peaks, and current utility as an epiphenomenon of nonadaptive structures.
    [Show full text]
  • Exaptation, Grammaticalization, and Reanalysis
    Heiko Narrog Tohoku University Exaptation, Grammaticalization, and Reanalysis Abstract The goal of this paper is to argue that exaptation, as introduced into the study of language change by Lass (1990, 1997), in specific functional domains, is a limited alternative to grammaticalization. Exaptation, similarly to grammaticalization, leads to the formation of grammatical elements. Like grammaticalization, exaptation is based on the mechanism of reanalysis. It decisively differs from grammaticalization, however, as it implies change in the opposite direction, namely from material absorbed in the lexicon back to grammatical material. Two sets of data are presented as evidence for the replicability of this process. One involves the occurrence of exaptation across languages in a specific semantic domain, namely, the evolution of morphological causatives out of lexical verb patterns. The other data pertain to recurrent processes of exaptation in one language, namely in Japanese, where exaptation figures in the development of various morphological categories. In all cases of exaptation, reanalysis is crucially involved. This serves to show that reanalysis may be more fundamental to grammatical change than both grammaticalization and exaptation. Furthermore, it allows for change both with the usual directionality of grammaticalization and against it. 1. Introduction Even detractors of grammaticalization theory do not seriously challenge the fact that in the majority of cases the morphosyntactic and semantic development of grammatical material follows the paths outlined in the standard literature on grammaticalization. The two following California Linguistic Notes Volume XXXII No. 1 Winter, 2007 2 issues, however, potentially pose a critical challenge to the validity of the theory. First, there is the question of the theoretical status of grammaticalization as a coherent and unique concept.
    [Show full text]
  • Exaptation-A Missing Term in the Science of Form Author(S): Stephen Jay Gould and Elisabeth S
    Paleontological Society Exaptation-A Missing Term in the Science of Form Author(s): Stephen Jay Gould and Elisabeth S. Vrba Reviewed work(s): Source: Paleobiology, Vol. 8, No. 1 (Winter, 1982), pp. 4-15 Published by: Paleontological Society Stable URL: http://www.jstor.org/stable/2400563 . Accessed: 27/08/2012 17:43 Your use of the JSTOR archive indicates your acceptance of the Terms & Conditions of Use, available at . http://www.jstor.org/page/info/about/policies/terms.jsp . JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range of content in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new forms of scholarship. For more information about JSTOR, please contact [email protected]. Paleontological Society is collaborating with JSTOR to digitize, preserve and extend access to Paleobiology. http://www.jstor.org Paleobiology,8(1), 1982, pp. 4-15 Exaptation-a missing term in the science of form StephenJay Gould and Elisabeth S. Vrba* Abstract.-Adaptationhas been definedand recognizedby two differentcriteria: historical genesis (fea- turesbuilt by naturalselection for their present role) and currentutility (features now enhancingfitness no matterhow theyarose). Biologistshave oftenfailed to recognizethe potentialconfusion between these differentdefinitions because we have tendedto view naturalselection as so dominantamong evolutionary mechanismsthat historical process and currentproduct become one. Yet if manyfeatures of organisms are non-adapted,but available foruseful cooptation in descendants,then an importantconcept has no name in our lexicon (and unnamed ideas generallyremain unconsidered):features that now enhance fitnessbut were not built by naturalselection for their current role.
    [Show full text]
  • Exaptation, Adaptation, and Evolutionary Psychology
    Exaptation, Adaptation, and Evolutionary Psychology Armin Schulz Department of Philosophy, Logic, and Scientific Method London School of Economics and Political Science Houghton St London WC2A 2AE UK [email protected] (0044) 753-105-3158 Abstract One of the most well known methodological criticisms of evolutionary psychology is Gould’s claim that the program pays too much attention to adaptations, and not enough to exaptations. Almost as well known is the standard rebuttal of that criticism: namely, that the study of exaptations in fact depends on the study of adaptations. However, as I try to show in this paper, it is premature to think that this is where this debate ends. First, the notion of exaptation that is commonly used in this debate is different from the one that Gould and Vrba originally defined. Noting this is particularly important, since, second, the standard reply to Gould’s criticism only works if the criticism is framed in terms of the former notion of exaptation, and not the latter. However, third, this ultimately does not change the outcome of the debate much, as evolutionary psychologists can respond to the revamped criticism of their program by claiming that the original notion of exaptation is theoretically and empirically uninteresting. By discussing these issues further, I also seek to determine, more generally, which ways of approaching the adaptationism debate in evolutionary biology are useful, and which not. Exaptation, Adaptation, and Evolutionary Psychology Exaptation, Adaptation, and Evolutionary Psychology I. Introduction From a methodological point of view, one of the most well known accusations of evolutionary psychology – the research program emphasising the importance of appealing to evolutionary considerations in the study of the mind – is the claim that it is overly “adaptationist” (for versions of this accusation, see e.g.
    [Show full text]
  • The Depths of Virus Exaptation Eugene V
    The depths of virus exaptation Eugene V. Koonin, Mart Krupovic To cite this version: Eugene V. Koonin, Mart Krupovic. The depths of virus exaptation. Current Opinion in Virology, Elsevier, 2018, Viral evolution, 31, pp.1-8. 10.1016/j.coviro.2018.07.011. pasteur-01977329 HAL Id: pasteur-01977329 https://hal-pasteur.archives-ouvertes.fr/pasteur-01977329 Submitted on 10 Jun 2020 HAL is a multi-disciplinary open access L’archive ouverte pluridisciplinaire HAL, est archive for the deposit and dissemination of sci- destinée au dépôt et à la diffusion de documents entific research documents, whether they are pub- scientifiques de niveau recherche, publiés ou non, lished or not. The documents may come from émanant des établissements d’enseignement et de teaching and research institutions in France or recherche français ou étrangers, des laboratoires abroad, or from public or private research centers. publics ou privés. 1 The depths of virus exaptation 2 1 2 3 Eugene V.Koonin and Mart Krupovic 4 1 National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, MD 20894 2 Unité Biologie Moléculaire du Gène chez les Extrêmophiles, Department of Microbiology, Institut Pasteur, 25 rue du Docteur Roux, Paris 75015, France 5 6 7 *For correspondence; e-mail: [email protected]; [email protected] 1 8 9 10 Abstract 11 12 Viruses are ubiquitous parasites of cellular life forms and the most abundant biological entities 13 on earth. The relationships between viruses and their hosts involve the continuous arms race but 14 are by no account limited to it.
    [Show full text]
  • The Mystery of Life's Origin
    The Mystery of Life’s Origin The Continuing Controversy CHARLES B. THAXTON, WALTER L. BRADLEY, ROGER L. OLSEN, JAMES TOUR, STEPHEN MEYER, JONATHAN WELLS, GUILLERMO GONZALEZ, BRIAN MILLER, DAVID KLINGHOFFER Seattle Discovery Institute Press Description e origin of life from non-life remains one of the most enduring mysteries of modern science. e Mystery of Life’s Origin: e Continuing Controversy investigates how close scientists are to solving that mystery and explores what we are learning about the origin of life from current research in chemistry, physics, astrobiology, biochemistry, and more. e book includes an updated version of the classic text e Mystery of Life’s Origin by Charles axton, Walter Bradley, and Roger Olsen, and new chapters on the current state of the debate by chemist James Tour, physicist Brian Miller, astronomer Guillermo Gonzalez, biologist Jonathan Wells, and philosopher of science Stephen C. Meyer. Copyright Notice Copyright © 2020 by Discovery Institute, All Rights Reserved. Library Cataloging Data e Mystery of Life’s Origin: e Continuing Controversy by Charles B. axton, Walter L. Bradley, Roger L, Olsen, James Tour, Stephen Meyer, Jonathan Wells, Guillermo Gonzalez, Brian Miller, and David Klinghoffer 486 pages, 6 x 9 x 1.0 inches & 1.4 lb, 229 x 152 x 25 mm. & 0.65 kg Library of Congress Control Number: 9781936599745 ISBN-13: 978-1-936599-74-5 (paperback), 978-1-936599-75-2 (Kindle), 978-1-936599-76-9 (EPUB) BISAC: SCI013040 SCIENCE / Chemistry / Organic BISAC: SCI013030 SCIENCE / Chemistry / Inorganic BISAC: SCI007000 SCIENCE / Life Sciences / Biochemistry BISAC: SCI075000 SCIENCE / Philosophy & Social Aspects Publisher Information Discovery Institute Press, 208 Columbia Street, Seattle, WA 98104 Internet: http://www.discoveryinstitutepress.com/ Published in the United States of America on acid-free paper.
    [Show full text]
  • Exaptation in Human Evolution: How to Test Adaptive Vs Exaptive Evolutionary Hypotheses
    doi 10.4436/jass.89015 JASs Invited Reviews Journal of Anthropological Sciences Vol. 89 (2011), pp. 9-23 Exaptation in human evolution: how to test adaptive vs exaptive evolutionary hypotheses Telmo Pievani & Emanuele Serrelli University of Milan Bicocca, Piazza dell’Ateneo Nuovo, n. 1 - 20126 Milan, Italy e-mail: [email protected]; [email protected] Summary - Palaeontologists, Stephen J. Gould and Elisabeth Vrba, introduced the term “ex-aptation” with the aim of improving and enlarging the scientific language available to researchers studying the evolution of any useful character, instead of calling it an “adaptation” by default, coming up with what Gould named an “extended taxonomy of fitness” . With the extension to functional co-optations from non-adaptive structures (“spandrels”), the notion of exaptation expanded and revised the neo-Darwinian concept of “pre- adaptation” (which was misleading, for Gould and Vrba, suggesting foreordination). Exaptation is neither a “saltationist” nor an “anti-Darwinian” concept and, since 1982, has been adopted by many researchers in evolutionary and molecular biology, and particularly in human evolution. Exaptation has also been contested. Objections include the “non-operationality objection”.We analyze the possible operationalization of this concept in two recent studies, and identify six directions of empirical research, which are necessary to test “adaptive vs. exaptive” evolutionary hypotheses. We then comment on a comprehensive survey of literature (available online), and on the basis of this we make a quantitative and qualitative evaluation of the adoption of the term among scientists who study human evolution. We discuss the epistemic conditions that may have influenced the adoption and appropriate use of exaptation, and comment on the benefits of an “extended taxonomy of fitness” in present and future studies concerning human evolution.
    [Show full text]