Re: The Baldwin Effect: What is it trying to say?
- From: Guy Hoelzer <hoelzer@xxxxxxx>
- Date: Mon, 5 Dec 2005 23:07:27 -0500 (EST)
I hope this thread gets plenty of attention. I am very interested in the
Baldwin effect myself and would like to understand it better.
in article dmve35$kve$1@xxxxxxxxxxxxxxxxxxx, whitesickle@xxxxxxx at
whitesickle@xxxxxxx wrote on 12/4/05 10:55 AM:
> Apparently the Baldwin Effect has some efficacy in computational models
> but I do not understand mathematics and I think computational modeling
> by itself is insufficient to make the evolutionary point. First, I read
> Baldwin's theory was intended to replace Lamarck's theory of aquired
> characteristics.
It might have that effect, but I don't think that was the goal.
> Second, I read Baldwin's Effect was associated with
> genetic assimilation and canalization but some researchers now are
> saying it doesn't depend on genetic assimilation.
I think the point of genetic assimilation and canalization under the Baldwin
effect was that these are means of codifying (making more permanent)
adaptive responses to environmental challenges that are plastic in
individuals. Perhaps the researchers suggesting that the Baldwin effect
does not depend on these mechanisms have discovered or imagined other
codifying mechanisms.
> Very strangely, the
> general point of Baldwin seems to be the phenotype(s) plasticity and
> effecting "changes" in it with no direct connection between phenotype
> and genotype. I'm inclined, unless it can be shown otherwise, the
> Baldwin Effect has had minimal effects on evolution.
IMHO there is no DIRECT connection between genotype and phenotype.
Development of phenotype is affected by an interaction between the genome
and the environment. Personally, I see the Baldwin Effect as potentially
very important in evolution. It might even be one of the most fundamental
aspects of evolutionary adaptation in the sense that mutations may rarely be
beneficial independent of the plastic behaviors expressed in the population.
I think this remains an open question.
> Learning is the most cited example of Baldwin's Effect. Yet ever since
> recorded civilization humans have remained basically unchanged by
> Darwinian evolution.
Wow. I find this to be wildly at odds with my personal viewpoint. What
reasoning or evidence do you have to support this claim.
> Our "learning" or education has increased as has
> our knowledge but genetically we haven't much.
I suppose the word "much" is subjective, so there is room for differing
opinion on this claim. In my estimation, the human gene pool has changed
enormously over the past few thousand years, given the constraints on gene
pool evolution that accompany rapid population growth. I think that gene
pools tend to change much more dramatically during times of population
contraction, given the same selection pressures.
> Therefore, there hasn't
> been any evidence of Baldwin's Effect on Darwinian evolution as I see.
> If one defines evolution to also entail cultural evolution then I would
> argue Baldwin's Effect has had some effect on evolution...but not a
> whole lot.
Well, yes I would certainly include cultural evolution in this subject,
because individually plastic behaviors can become codified as cultural
practices.
> The only way I see Baldwin's Effect having a signifigant
> effect is if the continuation of learning and knowledge goes beyond the
> idea of effecting changes in phenotypic plasticity without a direct
> connection between phenotype and genotype.
Here is a classic, though somewhat hypothetical, illustration. Pinnipeds
(seals and sea lions) evolved from canid ancestors. Imagine that the
environment of the ancestral canid population changed such that this
dog-like species was forced to forage for intertidal marine species, rather
than say hunting for other large mammals (maybe in packs). This would be
an example of behavioral plasticity. Now that these canids are depending
on their ability to hunt for marine prey, any mutation that makes them
better at doing so would be favored by selection. Had the canids not
manifested intertidal foraging behavior, this mutation would be of no value.
Hence, this population of canids might have evolved into an early form of
pinniped through the genetic codification of a behaviorally plastic change.
Does this seem unlikely to you? I could see how it might seem like an
unusual circumstance, but I would argue that we haven't explored this line
of thinking well enough to reject it as a general phenomenon.
Guy
.
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