DOCSLIB.ORG

The Heritability Fallacy David S

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
The Heritability Fallacy David S Primer The heritability fallacy David S. Moore1* and David Shenk2 The term ‘heritability,’ as it is used today in human behavioral genetics, is one of the most misleading in the history of science. Contrary to popular belief, the measurable heritability of a trait does not tell us how ‘genetically inheritable’ that trait is. Further, it does not inform us about what causes a trait, the relative influ- ence of genes in the development of a trait, or the relative influence of the envi- ronment in the development of a trait. Because we already know that genetic factors have significant influence on the development of all human traits, mea- sures of heritability are of little value, except in very rare cases. We, therefore, suggest that continued use of the term does enormous damage to the public understanding of how human beings develop their individual traits and identities. © 2016 Wiley Periodicals, Inc. How to cite this article: WIREs Cogn Sci 2016. doi: 10.1002/wcs.1400 INTRODUCTION represent something new and rather narrow. At that time, geneticists had a strictly deterministic under- f someone were to tell you that research has proven standing of how genes influence the formation of Ithat human intelligence is highly ‘heritable,’ what traits. They considered the relationship between genes would you think that means? Most people would and the environment to be akin to the relationship fi probably assume that it means people inherit a signi - between a plant seed and the rain that waters it: cant percentage of their intelligence directly, via their Genes were thought to contain specific, blueprint-like fi parents’ genes. In fact, though, the scienti c terms instructions for the formation of traits, whereas the ‘heritable’ and ‘heritability’ actually have very little to environment provided the nutrients and other salubri- do with genetic inheritance. This is confusing, because ous conditions that would allow those instructions to ‘heritability’ sounds like it means the same thing as unfold. According to this earlier way of thinking, a ‘inheritability.’ The confusion about what ‘heritabil- person’s DNA has specific instructions for blue eyes, fi ity’ actually measures signi cantly adds to a deep mis- or athletic arms, or a mathematical mind; the environ- understanding about how, exactly, our genomes ment merely allows for emphasis or de-emphasis of contribute to our observable characteristics (see Char- those already-designed traits. (If this sounds familiar, ney, Genes, behavior, and behavior genetics, WIREs it’s probably because it strongly resembles what many Cogn Sci, also in the collection How We Develop). of us were taught about genetics in grade school.) The term heritability was first given this new mean- ’ 1 THE APPROPRIATION ing in J. L. Lush s1937bookAnimal Breeding Plans. In that text, Lush proposed a calculation for what he called OF ‘HERITABLE’ ‘heritability’ that neatly codified the then-popular deter- For hundreds of years, the word ‘heritable’ was used ministic viewpoint. Because, Lush argued, an animal’s without confusion as a synonym for ‘hereditary.’ But phenotype (i.e., its observable traits, such as intelligence, in the early 20th century, the word was repurposed to height, eye color, etc.) is a function of genetic instructions plus the finishing influence of the environment, we should be able to statistically separate the influence of each.2 *Correspondence to: [email protected] Relying on mathematical guidelines from the geneticist 1Pitzer College and Claremont Graduate University, Claremont, CA, USA Sewall Wright, Lush proposed that in any given group: 2DeLTA Center, University of Iowa, Iowa City, IA, USA Vp phenotypic variation = Vg genetic variation fl fl Con ict of interest: The authors have declared no con icts of inter- ðÞ+ Ve environmentalðÞ variation est for this article. ðÞ © 2016 Wiley Periodicals, Inc. Primer wires.wiley.com/cogsci FIGURE 1 | Natural variability in human eye colors. Source: Sturm and Frudakis.3 Lush asserted that the Vg portion of that total them to correlations for that trait among fraternal can reasonably be termed ‘heritability,’ as it twins. Because identical twins share 100% of their revealed the portion of the trait variation that DNA and fraternal twins share, on average, only could be accounted for by variation in genes. The 50% of their DNA, this statistical comparison intention was ‘to quantify the level of predictability yields a crisp number that seems to highlight that of passage of a biologically interesting phenotype portion of a trait caused by genetic instruction. from parent to offspring’. In this way, the new Even though behavioral geneticists are sometimes technical use of ‘heritability’ accurately reflected careful to point out that each ‘heritability’ measure that period’s understanding2 of genetic determinism. only actually applies to variations in a specific Still, it was a curious appropriation of the term, group, they often use the term ‘heritability’ in a because—even by the admission of its proponents— way that conveys a sense of direct genetic influ- it was meant only to represent how variation in ence on traits. Also, because the term (if not its DNA relates to variation in traits across a popu- new-fangled scientific meaning) is so familiar to lation, not to be a measure of the actual influ- the public, the casual misinterpretation of the ence of genes on the development of any given term’s narrower meaning has been rampant in the trait. For example, in a large group of people popular press. For many decades now, we have with eyes of different colors (Figure 1), ‘Vg’ only been entertained with journalistic accounts of twin represents the extent to which variation in the studies suggesting that ‘personality is heritable’,4 group’sDNAaccountsforvariationindifferent ‘criminals are born, not made’,5 and ‘cheating eye colors in that group—not whether or how genes play [a] large role in female infidelity’.6 DNA is responsible for the development of eye Twin studies have reaffirmed the strong public color. In that sense, it was a highly misleading impression that some physical and personality new use of the term (even in the context of traits can be passed directly from parent to child determinism) that was bound to cause confusion: through DNA. While understandable, this impres- And indeed it did. sion is flatly incorrect, as brightly illustrated by three significant flaws in some scientists’ use of— and thus the public’s understanding of—the term TWIN STUDIES ‘heritability.’ The new use of the term caught on. Since that time, behavioral geneticists have conducted hun- THE GROUP VS. INDIVIDUAL FLAW dreds of studies derived from the Lush-Wright Although the original motivation for the concept of concept of heritability. The most prominent heritability was ‘to quantify the level of predictabil- method to determine heritability in human beings ity of passage of a biologically interesting pheno- has been statistical comparisons of identical and type from parent to offspring,’2 it is essential to fraternal twins. In what seems like a straightfor- realize that the equation Vp = Vg + Ve has no rele- ward approach, researchers compute correlations vance at all when it comes to individual develop- for a trait among identical twins and compare ment. The Vp in that equation refers to variation © 2016 Wiley Periodicals, Inc. WIREs Cognitive Science The heritability fallacy across individuals in a population, not to causal because there was zero variation in paint and con- processes that occur within any individual person. struction materials within this neighborhood. A Although the term ‘heritability’ is often misunder- statistical investigation focused on variation rather stood as speaking to the degree to which a certain than causation is, if not very narrowly interpreted, trait’s appearance in an individual is caused by likely to lead to a mistaken conclusion about what genetic factors, the logic underlying the equation caused the fires and about what can be done to nullifies that conceptualization. ‘Heritability,’ prevent them in the future. explains author Matt Ridley, ‘is a slippery concept, To see this, consider a newer neighborhood much misunderstood. For a start, it is a population right across the river in which every single home was average, meaningless for any individual person: you built with non-flammable aluminum and painted cannot say that Hermia has more heritable intelli- with fire-retardant paint. Even if this neighborhood gence than Helena. When somebody says that herit- has just as many space heaters, not a single home ability of height is 90 percent, he does not and here could ever catch fire. cannot mean that 90 percent of my inches come So what causes individual fires? The answer is from genes and 10 percent from my food.’ Instead, complex, and statistical variation surveys cannot he means that 90% of the variation in height in a address the question effectively; although all of the group of people can be accounted for, statistically, variation in fires in the fire-ravaged neighborhood by variations in those people’s DNA. But there is can be accounted for by focusing on space heaters no sense in which the specific DNA variations are alone, the fact remains that multiple factors— causing 90% of a person’s height. As Ridley notes, flammable building materials, the presence of heat ‘there is no heritability in height for the individual.’7 sources, and available oxygen, for example—are This group/individual distinction might seem responsible for collectively causing fires. Thus, focus- like a mere mathematical technicality, but it is not. ing on variation rather than causation can contribute Failing to recognize the distinction introduces a criti- to a misleading sense of how important a particular cal logical flaw that, on its own, completely under- factor might be in contributing to a particular mines the broad popular understanding of the term outcome.
Load more

Recommended publications
  • Heritability in the Era of Molecular Genetics: Some Thoughts for Understanding Genetic Influences on Behavioural Traits
    European Journal of Personality, Eur. J. Pers. 25: 254–266 (2011) Published online (wileyonlinelibrary.com) DOI: 10.1002/per.836 Heritability in the Era of Molecular Genetics: Some Thoughts for Understanding Genetic Influences on Behavioural Traits WENDY JOHNSON1,2*, LARS PENKE1 and FRANK M. SPINATH3 1Centre for Cognitive Ageing and Cognitive Epidemiology and Department of Psychology, University of Edinburgh, Edinburgh, UK 2Department of Psychology, University of Minnesota, Minneapolis, Minnesota, USA 3Department of Psychology, Saarland University, Saarbruecken, Germany Abstract: Genetic influences on behavioural traits are ubiquitous. When behaviourism was the dominant paradigm in psychology, demonstrations of heritability of behavioural and psychological constructs provided important evidence of its limitations. Now that genetic influences on behavioural traits are generally accepted, we need to recognise the limitations of heritability as an indicator of both the aetiology and likelihood of discovering molecular genetic associations with behavioural traits. We review those limitations and conclude that quantitative genetics and genetically informative research designs are still critical to understanding the roles of gene‐environment interplay in developmental processes, though not necessarily in the ways commonly discussed. Copyright © 2011 John Wiley & Sons, Ltd. Key words: genetic influences; twin study; heritability Much is often made of new findings of the presence of environmental influences but emphasised that these genetic influences
    [Show full text]
  • Transformations of Lamarckism Vienna Series in Theoretical Biology Gerd B
    Transformations of Lamarckism Vienna Series in Theoretical Biology Gerd B. M ü ller, G ü nter P. Wagner, and Werner Callebaut, editors The Evolution of Cognition , edited by Cecilia Heyes and Ludwig Huber, 2000 Origination of Organismal Form: Beyond the Gene in Development and Evolutionary Biology , edited by Gerd B. M ü ller and Stuart A. Newman, 2003 Environment, Development, and Evolution: Toward a Synthesis , edited by Brian K. Hall, Roy D. Pearson, and Gerd B. M ü ller, 2004 Evolution of Communication Systems: A Comparative Approach , edited by D. Kimbrough Oller and Ulrike Griebel, 2004 Modularity: Understanding the Development and Evolution of Natural Complex Systems , edited by Werner Callebaut and Diego Rasskin-Gutman, 2005 Compositional Evolution: The Impact of Sex, Symbiosis, and Modularity on the Gradualist Framework of Evolution , by Richard A. Watson, 2006 Biological Emergences: Evolution by Natural Experiment , by Robert G. B. Reid, 2007 Modeling Biology: Structure, Behaviors, Evolution , edited by Manfred D. Laubichler and Gerd B. M ü ller, 2007 Evolution of Communicative Flexibility: Complexity, Creativity, and Adaptability in Human and Animal Communication , edited by Kimbrough D. Oller and Ulrike Griebel, 2008 Functions in Biological and Artifi cial Worlds: Comparative Philosophical Perspectives , edited by Ulrich Krohs and Peter Kroes, 2009 Cognitive Biology: Evolutionary and Developmental Perspectives on Mind, Brain, and Behavior , edited by Luca Tommasi, Mary A. Peterson, and Lynn Nadel, 2009 Innovation in Cultural Systems: Contributions from Evolutionary Anthropology , edited by Michael J. O ’ Brien and Stephen J. Shennan, 2010 The Major Transitions in Evolution Revisited , edited by Brett Calcott and Kim Sterelny, 2011 Transformations of Lamarckism: From Subtle Fluids to Molecular Biology , edited by Snait B.
    [Show full text]
  • The Spice of Life the Variety of Life: a Survey and a Celebration of All the Creatures Snakes in the Grass That Have Ever Lived by Colin Tudge
    book reviews think that’s a false dichotomy.” She quotes, ating input from new methodologies, this is as this there is much to take issue with. In my but seems far less at home with, Sarah Hrdy’s heroism. Since the author took 10 years over own areas of special interest I found almost flat statement: “I did not come into science the job, he must have been daunted by how more to question and argue with than to and primatology because of a love for non- much the ground changed beneath his feet as agree with; and Tudge inevitably can only human primates. I was first attracted to prob- he progressed. When the world around you afford space for a thin overview of the real lems and to things I wanted to understand … is bursting with new kinds of information issues that excite us today. Indeed, for animal There is really no one way of doing science … that are just beginning to shed fresh light on phylogeny, the book only sparsely applies we need people to stress theory as much as a key question, it is a brave man who decides the information that is now emerging observation.” One of Jahme’s subjects, read- to write about the answer! So why has Colin from ‘evolutionary developmental biology’ ing the section about herself, murmured: Tudge done it? (which is revealing underlying similarities “Oh dear. This is half right and all wrong.” To Tudge’s answer is twofold: to help put tax- between diverse species in the structure of me that sums up the book, including some onomy back at the centre of biology (and the genes that control pattern formation and amazing scientific slip-ups.
    [Show full text]
  • High Heritability of Telomere Length, but Low Evolvability, and No Significant
    bioRxiv preprint doi: https://doi.org/10.1101/2020.12.16.423128; this version posted December 16, 2020. The copyright holder for this preprint (which was not certified by peer review) is the author/funder. All rights reserved. No reuse allowed without permission. 1 High heritability of telomere length, but low evolvability, and no significant 2 heritability of telomere shortening in wild jackdaws 3 4 Christina Bauch1*, Jelle J. Boonekamp1,2, Peter Korsten3, Ellis Mulder1, Simon Verhulst1 5 6 Affiliations: 7 1 Groningen Institute for Evolutionary Life Sciences, University of Groningen, Nijenborgh 7, 8 9747AG Groningen, The Netherlands 9 2 present address: Institute of Biodiversity Animal Health & Comparative Medicine, College 10 of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8QQ, United 11 Kingdom 12 3 Department of Animal Behaviour, Bielefeld University, Morgenbreede 45, 33615 Bielefeld, 13 Germany 14 15 16 * Correspondence to: 17 [email protected] 18 19 Running head: High heritability of telomere length bioRxiv preprint doi: https://doi.org/10.1101/2020.12.16.423128; this version posted December 16, 2020. The copyright holder for this preprint (which was not certified by peer review) is the author/funder. All rights reserved. No reuse allowed without permission. 20 Abstract 21 Telomere length (TL) and shortening rate predict survival in many organisms. Evolutionary 22 dynamics of TL in response to survival selection depend on the presence of genetic variation 23 that selection can act upon. However, the amount of standing genetic variation is poorly known 24 for both TL and TL shortening rate, and has not been studied for both traits in combination in 25 a wild vertebrate.
    [Show full text]
  • Environment-Sensitive Epigenetics and the Heritability of Complex Diseases
    INVESTIGATION Environment-Sensitive Epigenetics and the Heritability of Complex Diseases Robert E. Furrow,*,1 Freddy B. Christiansen,† and Marcus W. Feldman* *Department of Biology, Stanford University, Stanford, California 94305, and †Department of Bioscience and Bioinformatics Research Center, University of Aarhus, DK-8000 Aarhus C, Denmark ABSTRACT Genome-wide association studies have thus far failed to explain the observed heritability of complex human diseases. This is referred to as the “missing heritability” problem. However, these analyses have usually neglected to consider a role for epigenetic variation, which has been associated with many human diseases. We extend models of epigenetic inheritance to investigate whether environment-sensitive epigenetic modifications of DNA might explain observed patterns of familial aggregation. We find that variation in epigenetic state and environmental state can result in highly heritable phenotypes through a combination of epigenetic and environmental inheritance. These two inheritance processes together can produce familial covariances significantly higher than those predicted by models of purely epigenetic inheritance and similar to those expected from genetic effects. The results suggest that epigenetic variation, inherited both directly and through shared environmental effects, may make a key contribution to the missing heritability. HE challenges of identifying the common or rare genes a change in DNA sequence. Such modifications include Tthat contribute to the transmission of heritable human methylation of cytosine nucleotides at CpG sites and histone diseases and other complex phenotypes have been discussed protein modification. Such epigenetic modifications may be for some time (Moran 1973; Layzer 1974; Feldman and transmissible across generations or arise de novo each gen- Lewontin 1975; Kamin and Goldberger 2002).
    [Show full text]
  • THE DIALECTICAL BIOLOGIST 11 III II I, 11 1 1 Ni1 the DIALECTICAL BIOLOGIST
    THE DIALECTICAL BIOLOGIST 11 III II I, 11 1 1 ni1 THE DIALECTICAL BIOLOGIST Richard Levins and Richard Lewontin AAKAR THE DIALECTICAL BIOLOGIST Richard Levins and Richard Lewontin Harvard University Press, 1985 Aakar Books for South Asia, 2009 Reprinted by arrangement with Harvard University Press, USA for sale only in the Indian Subcontinent (India, Pakistan, Bangladesh, Nepal, Maldives, Bhutan & Sri Lanka) All rights reserved. No part of this book may be reproduced or transmitted, in any form or by any means, without prior permission of the publisher First Published in India, 2009 ISBN 978-81-89833-77-0 (Pb) Published by AAKAR BOOKS 28 E Pocket IV, Mayur Vihar Phase I, Delhi-110 091 Phone : 011-2279 5505 Telefax : 011-2279 5641 [email protected]; www.aakarbooks.com Printed at S.N. Printers, Delhi-110 032 To Frederick Engels, who got it wrong a lot of the time but who got it right where it counted ,, " I 1 1■ 1-0 ■44 pH III lye II I! Preface THIS Bow( has come into existence for both theoretical andpractical reasons. Despite the extraordinary successes of mechanistic reduction- ist molecular biology, there has been a growing discontent in the last twenty years with simple Cartesian reductionism as the universal way to truth. In psychology and anthropology, and especially in ecology, evolution, neurobiology, and developmental biology, where the Carte- sian program has failed to give satisfaction, we hear more and more calls for an alternative epistemological stance. Holistic, structuralist, hierarchical, and systems theories are all offered as alternative modes of explaining the world, as ways out of the cul-de-sacs into which re- ductionism has led us.
    [Show full text]
  • From Fox Keller, Back to Leibniz and on to Darwin
    Leibnizian Analysis in Metaphysics, Mathematics, Physics, Geology and Biology: From Fox Keller, back to Leibniz and on to Darwin Emily R. Grosholz I. Introduction The world of classical physics proposed a view of nature where systems behaved like machines: they were reducible to their parts, governed by universal laws (which were moreover time-reversal invariant), and thus representable by an axiomatized discourse where predictable events could be deduced, given the correct boundary conditions. Thus, the philosophers of science of the early and mid-twentieth century happily offered the Deductive-Nomological Model of Explanation (and Prediction). It fit Newton’s Principia, Book I, Proposition XI pretty well. However, it doesn’t really account for Book III, the development of the theory and practice of differential equations, the n-body problem, electro-magnetic phenomena, thermodynamics, atoms, galaxies or the expanding universe, limitations that even Thomas Kuhn, author of the revolutionary book The Structure of Scientific Revolutions, (University of Chicago Press, 1962) played down. But the philosophers did notice that the Deductive-Nomological Model of Explanation wasn’t a very good fit for biology, as after Darwin it struggled to account for natural history with its attendant one-way temporality, the emergence of novelty, and the intentionality and nested downwards complexity of living things, that seemed so stubbornly un-machine-like. The discovery of DNA and the rise of a new kind of machine, the computer, briefly encouraged philosophers (and scientists) to think that biology might finally look like a real science, populated by tiny robots that lend themselves to axioms and predictions; but, alas.
    [Show full text]
  • The Importance of Heritability in Psychological Research: the Case of Attitudes
    Psychological Review Copyright 1993 by the American Psychological Association, Inc. 1993, Vol. 100, No. 1,129-142 0033-295X/93/S3.00 The Importance of Heritability in Psychological Research: The Case of Attitudes Abraham Tesser It is argued that differences in response heritability may have important implications for the testing of general psychological theories, that is, responses that differ in heritability may function differ- ently. For example, attitudes higher in heritability are shown to be responded to more quickly, to be more resistant to change, and to be more consequential in the attitude similarity attraction relation- ship. The substantive results are interpreted in terms of attitude strength and niche building. More generally, the implications of heritability for the generality and typicality of treatment effects are also discussed. Although psychologists clearly recognize the impact of genet- heritabilities is both long and surprising. As noted earlier, the ics on behavior, their theories rarely reflect this knowledge. intellectual abilities domain has received the most press, and Most theories assume that behavior is relatively plastic and is the genetic contribution to that domain is well documented shaped almost entirely by situational parameters. The possibil- (e.g., Loehlin, Willerman, & Horn, 1988; Plomin & Rende, ity that a response may have a high heritability is often ignored. 1991). There is also evidence of genetic contributions to spe- I argue here that ignoring this possibility is consequential. The cific cognitive abilities, school achievement, creativity, reading vehicle used in this article is attitudes. This vehicle was chosen disability, and mental retardation (see Plomin, 1989, for a re- because it is a domain with which I have some familiarity; it is a view).
    [Show full text]
  • An Introduction to Quantitative Genetics I Heather a Lawson Advanced Genetics Spring2018 Outline
    An Introduction to Quantitative Genetics I Heather A Lawson Advanced Genetics Spring2018 Outline • What is Quantitative Genetics? • Genotypic Values and Genetic Effects • Heritability • Linkage Disequilibrium and Genome-Wide Association Quantitative Genetics • The theory of the statistical relationship between genotypic variation and phenotypic variation. 1. What is the cause of phenotypic variation in natural populations? 2. What is the genetic architecture and molecular basis of phenotypic variation in natural populations? • Genotype • The genetic constitution of an organism or cell; also refers to the specific set of alleles inherited at a locus • Phenotype • Any measureable characteristic of an individual, such as height, arm length, test score, hair color, disease status, migration of proteins or DNA in a gel, etc. Nature Versus Nurture • Is a phenotype the result of genes or the environment? • False dichotomy • If NATURE: my genes made me do it! • If NURTURE: my mother made me do it! • The features of an organisms are due to an interaction of the individual’s genotype and environment Genetic Architecture: “sum” of the genetic effects upon a phenotype, including additive,dominance and parent-of-origin effects of several genes, pleiotropy and epistasis Different genetic architectures Different effects on the phenotype Types of Traits • Monogenic traits (rare) • Discrete binary characters • Modified by genetic and environmental background • Polygenic traits (common) • Discrete (e.g. bristle number on flies) or continuous (human height)
    [Show full text]
  • How a Generation Was Misled About Natural Selection
    Gabora, L. (2011). How a Generation Was Misled About Natural Selection. Psychology Today (online). http://www.psychologytoday.com/blog/mindbloggling How a Generation Was Misled About Natural Selection Subtitle: Natural Selection: How it Works, How it Applies to Culture Liane Gabora Department of Psychology, University of British Columbia Okanagan Campus, Arts Building, 333 University Way, Kelowna BC, V1V 1V7, CANADA For 'Mindbloggling' column, Psychology Today Abstract This article explains how natural selection works and how it has been inappropriately applied to the description of cultural change. It proposes an alternative evolutionary explanation for cultural evolution that describes it in terms of communal exchange. When science is explained to the general public it is necessary to simplify. Inevitably details get left out, details that some consider important, and the ‘sexy' parts of the story get played up. But so long as the overall picture is more or less right, scientists generally appreciate the efforts of popular science writers, the press, and in some cases their fellow colleagues, to make their work accessible to a wider audience. The public in turn benefits from the opportunity to see the world they live in from a new perspective, and consider questions they might not otherwise have considered. Sometimes, though, the baby gets thrown out with the bathwater. The ‘babyless' version of a scientific story may be a hit nonetheless. Unless one has advanced training in a highly specialized area of a scientific discipline, it may appear to make sense. In most cases, the 1 misrepresentation of science doesn't make much difference; life goes on as normal.
    [Show full text]
  • The Fearless Vampire Conservator: Phillip Kitcher and Genetic Determinism*
    The Fearless Vampire Conservator: Phillip Kitcher and Genetic Determinism* 1. Introduction Genetic determinism is the idea that many significant human characteristics are rendered inevitable by the presence of certain genes; that it is futile to attempt to modify criminal behavior or obesity or alcoholism by any means other than genetic manipulation. Recent discussion of human cloning has revealed how real a possibility genetic determinism seems to many people. Surveying this discussion, developmental biologist Lewis Wolpert was amused to see so many ‘moralists who denied that genes have an important effect on behavior now saying that a cloned individual’s behavior will be entirely determined by their genetic make-up’ (Wolpert, 1998). His observation is accurate, and the vehemence of many attacks on behavioral genetics probably reflects an underlying belief that if genes affect behavior at all, then they must determine it. In fact, genes are very unlikely to be deterministic causes of behavior, for reasons I will come to in a moment. But if genetic determinism is unlikely to be true, why are we as a community so afraid of it? Wolpert seems to think that moral and political commentators on biology are simply ignorant, but the facts of which they are supposedly ignorant have been widely available for a very long time. Perhaps there is more to the strange persistence of genetic determinism. The psychologist Susan Oyama has famously compared arguing against genetic determinism to battling the undead: “But wait,” the exasperated reader cries, “everyone nowadays knows that development is a matter of interaction. You’re beating a dead horse.
    [Show full text]
  • Vp = Vg + Ve SNP, Duplication, Allele Frequencies Deletion, Etc
    Evolution by Natural Selection average phenotype changes environment Allele frequencies unfavorable for blue change Evolution w/o Selection average phenotype changes Drift rare alleles lost stochastic events Allele frequencies change Migration new alleles (genes) (gene flow) present gene flow from neigh- Allele frequencies bor population (species) change new alleles (genes) Mutation present Vp = Vg + Ve SNP, duplication, Allele frequencies deletion, etc. change Selection w/o Evolution selection between generations Development NO new alleles Plasticity Allele frequencies environment are unchanged unfavorable rounded phenotypes • Some phenotypic variants are favored by selection, they survive and reproduce better • But there is no genetic basis to this variation, the individuals with greater fitness have good luck rather than good genes GOAL: understand the genetic underpinnings of Behavior Singe gene vs. quantitative trait. Genes that are necessary for: Genes that Contribute to: Single Gene Quantitative or many genes Historic figure Mendel Galton identify dominant & recessive identify single genes define Genomic Architecture define mechanisms Immediate goals (#, location, interaction, specificity, linkage) quantify variation in a population describe change in gene frequency Sever disruptions Raw Materials used Lab induced (white coat) Subtle variation Naturally occurring (rubber boot) Tools us ed Bottom Up Forward Top D ow n ( = F or w ar d) Phenotype >>> Gene Observational mutagenesis/screening Comparative Genomics transgenesis Association
    [Show full text]