> DT> The basic assumption of many geneticists is that the genes
> DT> control everything - but this IS an assumption. It has
> DT> never been proved.
[snip]
> Yes, Lewontin makes good points about "DNA vs. destiny."
> Many attributes of any particular organism are not determined
> entirely by gene sequences but by other mechanisms as well
> (eg. environmental influences, regulatory systems,... even
> down to DNA methylation and chromosome packing). And we should
> be very careful at examining genetic data with regard to
> phenotypes. Relatively speaking, there are very few "simple"
> cases where genotype -> phenotype linkages can be easily
> assigned.
I am grateful for this feedback comment.
> [Aside: I do not believe most biochemists think we can
> understand everything about an organism by knowing its
> genome. Many are quite skeptical about genetic determinism,
> particularly as it has been applied to complex traits such
> as human behavior. Heck, we're still generally skeptical
> about the usefulness of results from DNA expresssion
> profiling...]
This aside does surprise me. Whilst I can understand why there is
skepticism about genetic determinism, it does appear to me that
genetic reductionism is very strong among biochemists. This view is
reinforced by the almost protesting challenges to genetic
reductionism that come from those on 'the fringe'.
As an example, I'll quote Harold (1995): do you think that most
biochemists would be comfortable with his view?
"Why do offspring resemble their parents in form and function? The
answer is not known, not even in principle, for the quest reaches
deep into the abiding mysteries of organised complexity (p.2765)."
"Most microbiologists look to the genome to play the architects role.
From where we now stand, this seems to me a rejection of reason.
All we have learned points to the conclusion that several epigenetic
layers intervene between genes and form. Morphogenesis cannot be
orchestrated by the genome, but makes manifest a higher level of
order, corresponding to the cellular scale of size and order
(p.2771)."
"The unstated premise that a cell is at bottom a self-assembling
structure carries reductionism to the point of absurdity (p.2774)."
Reference: Harold, F.M. 1995. From morphogenes to morphogenesis.
Microbiology. 141, 2765-2778.
Tim added a second aside:
> (Aside: Someone here mentioned that genetic determinism was something
> atheists would like everyone to believe. Odd that he would read
> your post, David, and skim over Lewontin's religious beliefs ;^)
Yes. I do find it interesting that there are great divergencies of
thinking between people who nominally have the same belief system.
We see it in Christian circles and we see it in Marxist circles. On
the other hand, I was very struck by the apparently "strange
alliance" between Christians, Marxists and Post-moderns on the nature
of science, and wrote it up as an article.
http://www.pages.org/bcs/Bcs089.html
I hope it is of interest.
Best wishes,
David J. Tyler.