January 15, 2012

Challenging genetic determinism

I have written a few posts before about how the old view of genetic and environmental influence on behavior isn't valid. In Bye bye genetic determinism I wrote about Chapter 2 of David Shenk's The Genius in All of Us: Why Everything You've Been Told About Genetics, Talent, and IQ Is Wrong. It said that the popular conception of the gene as a simple and powerful causal agent is not valid and should be replaced by a new interactionist model which describes the role of genes more accurately is briefly summarized as 'GxE'. In Exit genetic determinism: example of genes-environment interaction I summarized a dramatic demonstration of this genes-environment interaction which dates back to 1958 when researchers Rod Cooper and John Zubek did an experiment with rats.

As Carol Dweck has demonstrated frequently, self-beliefs have important consequences. Likewise, what we believe about how genes and environments shape our behavior is important. Is it so that important characteristics of people are 1) primarily cause by our genes, 2) primarily caused by environmental influences? 3) partly by genes and partly by environments, or 4) by a complex interaction of genes and environments?

A new book, Challenging Genetic Determinism. New Perspectives on the Gene in its Multiple Environments, reports on advances in genetic research. Here are some quotes from the book:
  1. "Genetic-determinist explanatory models have been thoroughly discredited by more sophisticated research." ~Louis Maheu and Roderick Macdonald  
  2. "Until the end of the past century, quantitative genetics data offered, at best, only a description of certain relationships between unspecified genes' effects [...] and some liabilities for certain traits. Moreover, this black box statistical association could not be generalized to larger populations; the results obtained were more or less generalized to larger populations."  ~Louis Maheu and Roderick Macdonald 
  3. "The successful sequencing of the human genome helped substitute for these genetically unspecified effects research into measurable effects of identified genes. [...] After a period of considerable research enthusiasm, however, the revised quantitative genetics approach ultimately did not meet the expectations raised by advances in molecular genetics."  ~Louis Maheu and Roderick Macdonald 
  4. "Public discourse may be galloping far ahead of what is warranted by a more sober and rigorous assessment of progress in the genetic analysis of human behaviors and abilities, especially intelligence [...]" ~ Douglas Wahstein. 
  5. "Behavioral genetic research provided "the best available evidence for the impact of the environment" ~Louis Maheu and Roderick Macdonald 
  6. "In order to study non-additive synergistic interplays between gene and environment much more sophisticated conceptual frameworks and research strategies are required. [...] Such models would emphasize that specific behaviors ultimately are the outcomes of genetic influences only if and when they are also fashioned by facilitative or transformative effects exercised by environmental factors. Of course, the potential for a reverse causality pattern would equally be emphasized in these models. Specific behaviors could stem from environmental factor influences being mediated or moderated by active genetic factors."  ~Louis Maheu and Roderick Macdonald 
  7. "Epigenetic regulations of gene expressions are at the cutting edge of modern molecular genetics."  ~Louis Maheu and Roderick Macdonald 
  8. "Preliminary studies suggest that adverse rearing environments can induce negative effects on gene expression." ~Louis Maheu and Roderick Macdonald 
  9. "There is generally little relation between scores on a psychological test of these characteristics and reproductive success, which helps explain why such great individual variation persists generation after generation." ~ Douglas Wahstein.
  10. "Decades of research on the genetic aspects of animal behavior have taught us well that no behavior is inherited in any simple manner and environmental influences are involved to some extent in virtually all behaviors of any degree of complexity."  ~ Douglas Wahstein. 
  11. "Anthropologists and geneticists have largely abandoned the race concept because they recognize that lines of demarcation among populations are arbitrary and that the vast majority of genetic variation resides within geographic populations rather than between [...]" ~ Douglas Wahstein. 
  12. "[I]t is important to distinguish three general kinds of genetic influences: (i) Mendelian genetic disorders involve a major defect in one specific gene, (ii) Complex psychiatric disorders involve the combined actions of a small number of abnormal genes, each of which has a relatively modest effect, (iii) Continuous characteristics have a wide range of normal values and the outcome is influenced by a large number of genes, each with a small effect. It should be emphasized that all three kinds of phenomena are subject to environmental influences."  ~ Douglas Wahstein. 

7 comments:

  1. I have way to little knowledge in this field so... this looks strange to me.

    To me, it looks even silly.

    Current human evolution takes place in the noosphere and although the genes play a role, the structure of the local noosphere is way way way more important. An infant born in Denmark will evolve into a different adult than an infant born in Bangladesh and this will not be due to his genes but due to the local noosphere. The local environment.

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  2. Hi Peter,

    The point of this new way of looking at how individuals develop is to not say: "This percentage of development is caused by genes and this percentage is caused by environment." This way of thinking refers to the nature versus nurture debate. It focuses on the question: what percentage is cause by nature (genes) and what by nurture (environment).

    The new GxE framework says: "Genes and environment interact in virtually every aspect of development." This is sometimes called nature VIA nurture. It says 1) that genes affect sensitivity to environmental influences and 2) that environmental factors affect the extent to which genetic influences are expressed.

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  3. Thanks for clearing this up, Coert.

    What do you think about our environments?

    I've seen some presentations regarding Dacher Keltner's "Born To Be Good" and I've always thought about what would happen if children would be raised according to those theories, encouraging the genetic tendency towards cooperation, empathy and compassion. :)

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  4. Hi Peter,

    I don't know Dachter Keltner's work but I think environments are extremely important. Two things come to mind which I find extremely important: 1) to create a stimulating and positive environment for children. There is much evidence for the beneficial effects of talking a lot to children and to challenge and encourage them a lot, 2) to learn children to be careful in choosing what they believe and what they don't belief. One set of beliefs which is important is self-beliefs. Carol Dweck's work is an example of how different the effects of different sets of self beliefs are (fixed mindset versus growth mindset).

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  5. This comment has been removed by the author.

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  6. Try his TED talk when you will find some 18 min. :


    I believe you might like it.

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