thank you for this very clear exposition. I stand corrected, even
challenging the "limitations of genetic explanations" falls into the
trap of accepting as fact things which have yet to be shown. In terms
of challenging reductionist explanations how do we apply this
understanding to the types of statistical correlations that are put our
asserting "statistical significance" in noticing the correlation with a
particular gene variant and some observed behavior? Much of my
skepticism is based on the idea that behaviors such as intelligence are
quite subjective no matter how one protests the objectivity of IQ tests
and I am not clear about the size and heterogeneity of the populations
that are used to make such claims. The same would appear to be true in
terms of evaluating aggressiveness and altruism, especially in human
NEWMAN STUART wrote:
>Given what genes actually do (specify primary sequences of proteins, and
>they don't even do that in a straightforward fashion--almost every RNA
>transcript in vertebrates is spliced, and at least half are alternatively
>spliced), the idea of a "genetic explanation" for any trait at all, let
>alone behaviors and beliefs, is problematic. There are clearly some cases
>in which morphology (e.g., wrinkling of peas, number of fingers in humans),
>a disease propensity (for sickle cell disease, cystic fibrosis), a sensory
>capability (color blindness, perfect pitch), and undoubtedly behavioral
>propensities, are strongly influenced by one or more genes. But in none of
>these cases does there exist a genetic explanation of the trait affected by
>the gene variants.
>Any complex system can be sent along one or another of its potential
>pathways by small changes in a subset of its components. If the origination
>of a character (trait, shape, behavior) is ontologically distinct from the
>mutation that elicits one or another version of the character, the
>sociobiological/evolutionary psychological style of assertion that most
>species-specific commonalities in human form and behavior are "genetic"
>becomes indistinguishable from saying they are "biological." Moreover, the
>multiplicity of way our species differs from the next nearest ones makes it
>in principle impossible to determine the extent to which our proteins define
>our species nature. Furthermore, the assertions of sociobiologists and
>evo-psychologists that some behavioral differences between groups are
>"genetic" is also a category mistake. The only rational meaning this could
>have is that some protein variants selected for at earlier stages of human
>evolution influence developmental pathways responsible for behavior
>patterns. Although this is plausible, it has not been shown for any human
>protein/behavior, and processes other than genetic mutation, many of which
>are reversible (stress, malnutrition) can also influence developmental
>If human evolution is analogized to domestication of animals (Darwin's
>favorite model for evolution), with humans domesticating themselves, it
>might be argued that different groups are distinguished by genetic changes
>similar to those that separate domestic breeds from their wild counterparts.
>But in perhaps the best studied case of experimental domestication (see
>Trut, L. N. (1999). Early canid domestication: the farm-fox experiment.
>American Scientist 87, 160-169; Prasolova, L. A. and Trut, L. N. (1993).
>Effect of the "Star" gene on the rate of melanoblast migration in silver fox
>(Vulpes vulpes) embryos. Dokl Akad Nauk 329, 787-9) the differences between
>domesticated and nondomesticated strains are not mutations--actual changes
>in gene sequence--but paramutation--reversible modification in the chemical
>modification or chromosomal configuration of a gene that affects its
>expression (Hollick, J. B., Dorweiler, J. E. and Chandler, V. L. (1997).
>Paramutation and related allelic interactions. Trends Genet 13, 302-8).
>This is probably why domesticated animals often revert to their feral
>appearance and behavior after a few generations in the wild.
>The relation of genes to complex traits is an area that is still unresolved
>for systems in which the most precise experimental methods are available.
>It is clear, however, that inheritance of traits almost never means there
>are genes "for" that trait, and differences between individuals with regard
>to a trait, even if the trait breeds true, doesn't necessarily mean that
>there are allelic (gene sequence) differences between those individuals. So
>what are evolutionary psychologist talking about?
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