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?
From: Ivan Handler
To: [log in to unmask]
Sent: 11/2/02 5:45 PM
Subject: Re: What are we doing here?
I am definitely in favor of this direction expecially these questions
Dick Levins just put out.
The questions that I would add related to Dick's contribution are these:
1. What are the inherent limitations on genetic explanations? All
explanations that can be qualified as scientific have to be based on our
ability to gather evidence both for and against (Popper's notion of
falsification). Information gathering is not free it is subject to the
2nd law of thermodynamics as is everthing else. In particular this
means that there are always information losses (entropy implies that not
all of the energy in a system is available to do work which implies that
it is not possible to know all of the internal states of a system). On
the other hand chaotic dynamics informs us that that systems whose
behavior varies wildly due to insignifigant, immeasurable variations in
initial conditions are quite common. Given that it appears that
biological systems fall into the chaotic category, it seems that the
attempt to characterize behavior of systems given simple physical
initial conditions which vary from individual to individual and can not
be measured with great precision, such as genetic determinism or
quasi-determinism (really the same thing with various qualifications
that other things may matter, but no questions or research directed
toward what those other things are) would be doomed to failure were it
not for the attractiveness of the view among many people independent of
its explanatory power.
Another way of saying this is to pose the question on how much
information can cross hierarchical boundaries? From gene to cell,
from cell to tissue, from tissue to organ, from organ to system,
from system to individual and from individual to society. Not only
are there information losses on the way, other information at the
same level of hierarchy also appears from other sources, the
the environment. Reductionists seem to presuppose that information
flows freely accross these boundaries, there is much room for
skepticism on this point.
To my mind this means that many subjects must be studied in their own
domains. While a knowledge of genetics and neurphysiology can be very
important to psychologists and therapists, it is hardly ever decisive.
The basic elements of the domain being studied must be developed by the
people researching the subject, they can not be deduced from the
structural elements that make up a physical body. To posit that
psychology would become a subdomain of evolutionary biology is absurd.
2. What kinds of things about behavior can be deduced from biological
structure? I think the answers are probably more along the lines of the
kinds of spectra of behavior that a biological system can support rather
than attempting to deduce the existence of specific behaviors such as
altruism or aggression. I am no biologist, but it seems peculiar to me
that the focus of evolutionary psychology is to explain specific human
behaviors rather than, at least as a starting point, to understand how
to characterize and/or parameterize the whole behavior spectrum.
Without an adequate understanding of the size of the domain being
studied, it seems to me that it is impossible to escape the conclusion
that the topics being studied are arbitrary and based on the subjective
biases of those doing the research. That is not necessarily a bad thing
in itself, but I think it becomes problematic when larger questions are
not acknowledged or even dismissed as seems to be the case.
3. How independent is the social structure of humans (and other animals
with socital structures) from biology? This is probably just a
paraphrase of Dick's questions. In particular, the kinds of questions
to ask here are how much behavior does not vary as environment changes
and how much behavior does change as the environment remains fixed?
Biological determinism must argue that behavior is an adaptation to the
environment, so if it remains fixed when the environment changes, that
set of behaviors must not be based on any genetic (or at least any
detectable) structure and conversely, if behavior changes when the
environment is fixed, it becomes hard to see how one could argue that
genes are responsible. The other issue here that has been raised in
the past is the pace of behavioral change compared to the pace of
genetic change. Even when a behavior does "track" the environment,
if that behavior changes in new creative ways faster than the pace
of genetic change (which I understand is measured in tens of thousands
of years), then there is another major discontinuity with the relation
between behavior and genetics. These are fairly simple ideas, I think
they can be strengthened.
I like Dick's idea that we "... not let the reductionists set the
agenda". That was the case during the sociobiology debate which I think
by all accounts we won. We might as well try again.
Richard Levins wrote:
> 3. Our own alternative approach. The question of the appearance of
> behaviors is a worth while topic.This should start from the assertion
> both continuity and discontinuity in human evolution that would help
> understand what we mean by "traits". I do not doubt that the physical
> chemical organization of the brain is the starting point. Questions of
> connectivity and neurotransmission are relevant, but to what? Human
> requires that we imagine the product before it is made. This capacity
> visualize is then available to visualize all sorts of other things
> have no evolutionary significance but are humanly important. The
> are active in a stress response, but the adrenal rush is not
> aggressive. It can be euphoric. So yes, in a sense corticosteroids may
> be a
> precondition for some kinds of aggressive behavior (spontaneous
> aggressiveness, not premeditated aggression that is part of the
> "cost/benefit" analysis by criminals or the impersonal aggressiveness
> the warmakers). And a gene that inhibited synthesis of these molecules
> alter the behavioral options(sugar levels might not rise much, blood
> pressure and heart rate may be stable). But this in no way explains
> "aggression". Similar, language makes limericks and sonnets possible
> but a
> biochemical variant that makes word recall slower or faster would not
> be a
> gene for poetry. The task of a real integration of the biological and
> social is to show the emergence of human behaviors out of human social
> arrangements on a substrate of rather general biological capacities.
> Or we
> could start with a problems such as, how have people coped with the
> variability of the environment? The basic modes are detection with
> response, prediction, broad tolerance, prevention and mixed
> strategies. We
> could examine any of these to see how they emerge from pre-human
> modes. For
> instance, all animals face food shortage. Food could be stored in the
> as fat, in the ground as acorns, in more abstract form as social
> bonds, or
> more recently as wealth and money, in which case it can be insatiable.
> where we do not have social/cultural mechanisms to cope with the
> environment, biological and behavioral modes persist. For instance in
> short- and long term survival at high elevation.
> Let's not let the reductionists set the agenda.
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