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PAUL E. GRIFFITH JAMES TABERY Behavior Genetics and Development: Conceptual and historical causes of controversy O'Rourke, Enhancing Communication & Collaboration.

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Presentation on theme: "PAUL E. GRIFFITH JAMES TABERY Behavior Genetics and Development: Conceptual and historical causes of controversy O'Rourke, Enhancing Communication & Collaboration."— Presentation transcript:

1 PAUL E. GRIFFITH JAMES TABERY Behavior Genetics and Development: Conceptual and historical causes of controversy O'Rourke, Enhancing Communication & Collaboration in Interdisciplinary Research © 2014 SAGE Publications Inc

2 ‘Statistics’ 'Those Platonists are a curse,' he said, 'God's fire upon the wane, A diagram hung there instead, More women born than men.' W.B Yeats, 1933 O'Rourke, Enhancing Communication & Collaboration in Interdisciplinary Research © 2014 SAGE Publications Inc

3 What is Behavior Genetics? Disciplines can (and should) be defined both methodologically and sociologically (Hull, 1988) Sociologically, the discipline can be traced back to Fuller and Thompson’s Behavior Genetics (1960) and the foundation of the Behavior Genetics Association by Theodosius Dobzhansky, and the journal Behavior Genetics, both in 1970 Methodologically, traditional behavior genetics is the application of the methods of quantitative genetics to behavioral traits O'Rourke, Enhancing Communication & Collaboration in Interdisciplinary Research © 2014 SAGE Publications Inc

4 Quantitative genetics Fisher showed in 1918 that statistical procedures for studying correlations between phenotypes could be interpreted in Mendelian terms. In the simplest models of this kind, quantitative traits are treated as if they were the effect of a large number of genes each of which makes an equal contribution to variation in the character Phenotypic variance can be partioned into genetic and environmental components (main effects): VP = VG + VE Additional terms can be added to take account of genotype- environment interaction and nonrandom distribution of genotypes across environments Ronald A. Fisher O'Rourke, Enhancing Communication & Collaboration in Interdisciplinary Research © 2014 SAGE Publications Inc

5 What is Developmental Psychobiology? The most persistent scientific critics of traditional behavior genetics have been developmental psychobiologists Methodologically, DP is the causal elucidation of behavioral development through experimental research, integrating genetic analysis with behavioral embryology DP is much less well-known in philosophy than BG. An introductory textbook is George F. Michel and Celia L Moore (1995), Developmental Psychobiology: An interdisciplinary science. Cambridge, MA: MIT Press. O'Rourke, Enhancing Communication & Collaboration in Interdisciplinary Research © 2014 SAGE Publications Inc

6 What is Developmental Psychobiology? Sociologically, DP emerged in the 1960s from research traditions in comparative psychology. The International Society for Developmental Psychobiology was founded in 1967 and the journal Developmental Psychobiology in 1968 The term 'psychobiology' has been used in diverse ways in the past century, but usually with the intention of preventing some psychological phenomenon, in this case development, disappearing in the enthusiasm for a successful reductionistic research strategy (Dewsbury 1991) O'Rourke, Enhancing Communication & Collaboration in Interdisciplinary Research © 2014 SAGE Publications Inc

7 What is ‘Developmental Behavior Genetics’? Since the mid 1980s there have been numerous calls for the integration of these two fields, or ‘DBG’ But, unsurprisingly, researchers in traditional behavior genetics and researchers in developmental psychobiology have very different views on what would constitute a truly ‘developmental’ behavior genetics O'Rourke, Enhancing Communication & Collaboration in Interdisciplinary Research © 2014 SAGE Publications Inc

8 The BG vision of DBG “…the study of genetic and environmental influences on individual differences in behavioral development” (Robert Plomin 1983, 253) Like traditional BG, DBG seeks causes of phenotypic differences, rather than phenotypes, and asks 'how much' phenotypes depend on causes, rather than 'how‘ The application of fairly traditional behavior genetic methods to developmental data, that is, to repeated observations of the same phenotype at different stages of development – the study of “distributions of individuals developing across time” (Sandra Scarr 1995, 158) DBG will show how much of the observed differences between the developmental trajectories of children can be attributed to genetic differences, differences in shared and non-shared environment, correlations between genes and environment, and so forth O'Rourke, Enhancing Communication & Collaboration in Interdisciplinary Research © 2014 SAGE Publications Inc

9 The DP vision of DBG The new discipline must set out to explain behavioral development rather than differences in behavioral development It must ask how genes cause development rather than how much development genes cause Observations of distributions in populations must be replaced by time- series data on individuals Observational data must be supplemented by experimental data See esp. Gottlieb, Gilbert (1995), "Some conceptual deficiencies in 'developmental' behavior genetics", Human Development 38: ; (2003), "On Making Behavioral Genetics Truly Developmental", Human Development 46 (6): O'Rourke, Enhancing Communication & Collaboration in Interdisciplinary Research © 2014 SAGE Publications Inc

10 Controversy over behavior genetics and development “In some discussions ‘interactionism’ has become merely a substitute for extreme environmentalism…. Thus the interactionist theory holds that although there may be significant genetic differences at the time of conception, the organism’s development involves such complex interactions with the environment that the genetic blueprint, so to speak, becomes completely hidden or obscured beneath an impenetrable overlay of environmental influences.” (Jensen 1973) “The cellular context did not merely determine the magnitude of the glucocorticoid receptor effect on gene transcription, it determined whether that effect was positive or negative - all in relation to a single DNA target. The cellular context, and specifically levels of transcription factors such as cFos and cJun, are heavily influenced by ongoing activity; stress, social encounters, all serve to influence the cellular levels of these factors and can therefore have very potent influences on the nature of gene activity. From such systems we will derive main effects! I think not.” Meaney (2001, ) O'Rourke, Enhancing Communication & Collaboration in Interdisciplinary Research © 2014 SAGE Publications Inc

11 Conceptual causes of controversy 1. Different concepts of ‘interaction’ 2. Different interpretations of the reaction norm concept 3. Different conceptions of gene and gene action O'Rourke, Enhancing Communication & Collaboration in Interdisciplinary Research © 2014 SAGE Publications Inc

12 Two concepts of interaction 1. Developmental outcomes are always causally dependent on genetic causes and on non- genetic causes 2. There is sometimes a statistical interaction between the genetic and environmental components of variance: V P = V G + V E + V GxE 3. Tabery has labelled these GXE D and GXE B Norms of Reaction for low-bar and ultra-bar Drosophila (From Hogben 1933a). O'Rourke, Enhancing Communication & Collaboration in Interdisciplinary Research © 2014 SAGE Publications Inc

13 BG’s ‘defense-by-distinction’ “It is common for theorists of the heredity × environment controversy to confuse the statistical concept of interaction with a viewpoint called interactionism. The problem arises because each concept applies at a different level of analysis.” (Bouchard and Segal 1985) The ubiquity of GXE D is irrelevant to behavior genetics, which is concerned solely with GXE B - statistical interaction. BG can safely ignore data, derived from DP, on the ‘interaction’ of genes and environment in development. Moreover, ‘interactionism’ is woolly holism: “Unfortunately, discussions of genotype-environment interaction have often confused the population concept with that of individual development. It is important at the outset to distinguish genotype-environment interaction from what we shall call interactionism, the view that environmental and genetic threads in the fabric of behavior are so tightly interwoven that they are indistinguishable.” (Plomin et al 1997) O'Rourke, Enhancing Communication & Collaboration in Interdisciplinary Research © 2014 SAGE Publications Inc

14 The connection beneath the distinction The view that GXE D cannot be invoked in discussions of population level phenomenon like variance is too strong Just as genetic differences between individuals causally explain V G, differences in genotype- environment combinations between individuals causally explain V GXE The ubiquity of GXE D is relevant to behavior genetics because it constitutes ‘silent variance’ – potential control parameters which can, counterfactually, generate statistical interaction O'Rourke, Enhancing Communication & Collaboration in Interdisciplinary Research © 2014 SAGE Publications Inc

15 Reaction norm, Reaction range The reaction norm - a graphical depiction of the phenotypic values of a genotype across a range of environments is a natural framework in which to present the inevitable inter-dependence of gene and environment. It is often regarded as a royal road to avoiding ‘genetic determinism’ (e.g. Kitcher 2001) O'Rourke, Enhancing Communication & Collaboration in Interdisciplinary Research © 2014 SAGE Publications Inc

16 Reaction norm, Reaction range The reaction range concept is popular in BG, and presented as a more operational derivative of the reaction norm concept It has been criticised for illicitly importing the idea of limits to the effect of environment, limits determined by the genotype – ‘genetic potential’ O'Rourke, Enhancing Communication & Collaboration in Interdisciplinary Research © 2014 SAGE Publications Inc

17 Two concepts of the gene Behavior genetics, and quantitative genetics more generally, conceptualizes genes in a manner continuous with classical, Mendelian genetics, as intervening variables in the genetic analysis of phenotypes Alleles are statistical markers of phenotypic differences At the molecular level, such a ‘gene’ can be an any functional element, not only a coding sequence O'Rourke, Enhancing Communication & Collaboration in Interdisciplinary Research © 2014 SAGE Publications Inc

18 ‘Abstract developmental genes’ Gottlieb 1992 (above) and Waddington 1957 (left) depict genes genes as determinants of the value of certain parameters in a developmental model O'Rourke, Enhancing Communication & Collaboration in Interdisciplinary Research © 2014 SAGE Publications Inc

19 Genetic explanations An abstract developmental gene, by its nature, can only explain a phenotype via the mediation of many other developmental parameters If we conceive of genes in this manner, as interactive causes of development, then it will seem unsatisfactory to explain the presence of a phenotype (or difference) by alluding to the presence of a particular gene in the absence of any understanding of its role in development In contrast, if we conceive of genes as Mendelian alleles, then it will seem unreasonable to demand knowledge about how a gene interacts with other genes and with the environment before accepting an explanation which cites the presence of this allele. If the organism or organisms whose phenotypes are to be explained have been drawn from a suitable reference class, then the facts that caused the gene to be cited as an explanation imply that those other parameters will not make a difference. How, then, can they bee explanatorily relevant O'Rourke, Enhancing Communication & Collaboration in Interdisciplinary Research © 2014 SAGE Publications Inc

20 Political motives The debate over statistical techniques for the study of heredity has been politicized since its inception. Fisher’s critics were partly motivated by opposition to hiss eugenic ideas. In the 1970s, comparisons with Nazi race-science were met by comparisons with Stalin's suppression of 'Morgano-Mendelism'. The philosopher Neven Sesardic's has recently claimed that there is no substance to criticisms based on the idea of GXE and on the norm of reaction concept - the entire discipline of philosophy of science has a structural bias against hereditarian explanations (Sesardic 2005 see esp ). We reject this view. Scientists have been talking past each other, but this is at least partly because they are separated by real, conceptual differences rooted in the different methodologies of their research traditions, not merely because they come from different political orientations O'Rourke, Enhancing Communication & Collaboration in Interdisciplinary Research © 2014 SAGE Publications Inc

21 Future research directions? Application of statistical, population approaches to genuine, time-series data - Molenaar, P C. M., et al (2003), "The relationship between the structure of interindividual and intraindividual variability: A theoretical and empirical verification of developmental systems theory", in U.M Staudinger and U Linderberger (eds.), Understanding Human Development, Kluwer, The burden of proof on the reality of statistical interaction – Fuller, Trevon, Sahotra Sarkar, and David Crewe (2005), "The use of norms of reaction to analyze genotypic and environmental influencees on behavior in mice and rats", Neuroscience and Biobehavioral Reviews 29: The parallel ‘molecular revolution’ in BG (e.g. Hamer, Dean (2002), "Rethinking behavior genetics", Science 298:71-72) and DP (e.g. John T. Cacioppo and Gary G Berntson, eds. (2004), Essays in Social Neuroscience. MIT Press.) O'Rourke, Enhancing Communication & Collaboration in Interdisciplinary Research © 2014 SAGE Publications Inc

22 GRIFFITHS, P. E., & TABERY, J. G. (2008). BEHAVIORAL GENETICS AND DEVELOPMENT. NEW IDEAS IN PSYCHOLOGY, 26(3), PAUL GRIFFITHS’ WORK WAS SUPPORTED BY ARC FEDERATION FELLOWSHIP FF JAMES TABERY’S RESEARCH WAS FACILITATED BY TRAVEL FUNDING FROM THE EGENIS, THE ESRC CENTER FOR GENOMICS IN SOCIETY AT THE UNIVERSITY OF EXETER. Acknowledgments O'Rourke, Enhancing Communication & Collaboration in Interdisciplinary Research © 2014 SAGE Publications Inc


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