Re: The Baldwin Effect: What is it trying to say?

William Morse wrote:
> Guy Hoelzer <hoelzer@xxxxxxx> wrote in
> news:dn32pv$2c98$1@xxxxxxxxxxxxxxxxxxx:
>
>
>>I hope this thread gets plenty of attention. I am very interested in
>>the Baldwin effect myself and would like to understand it better.
>>
>>in article dmve35$kve$1@xxxxxxxxxxxxxxxxxxx, whitesickle@xxxxxxx at
>>whitesickle@xxxxxxx wrote on 12/4/05 10:55 AM:
>
>
>
>>>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.
>
>
> (snip)
>
>
>>>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
>>
>>
>
>
> I have understood the Baldwin effect to be the extension to learned
> behavior of the general process by which an organism's behavior affects
> the environment, which in turn changes the selection pressure acting on
> the population. To give an example where learning is not involved, once a
> species of plant figured out how to make woody trunks so they could raise
> their leaves higher than competitors, it affected which of that species
> of plants own seeds would survive - the ones that could grow tall trunks.
>
>
> Baldwin recognized that learned behavior could act the same way, in which
> case evolution might appear to be Lamarckian, especially if a behavior
> that was initially learned became genetically programmed in later
> generations. The illustration of a change in foraging behavior in canids
> is an excellent one. The evolution of the beaver is another example - as
> the proto-beaver starts to take advantage of natural dams and learns to
> improve on them, it changes what traits will be advantageous in future
> proto-beavers.
>
>
> So I see the Baldwin effect as having very general applicability in
> understanding evolution - potentially coming into play anytime an
> organism has a significant and consistent impact on its environment and
> can change that impact through learning.
>
> Now as to Michael's argument that the Baldwin effect can't be significant
> because we haven't seen any change in human genetics in the past 10,000
> years, I would note several points:
>
> As of 10,000 years ago the human population was already rather large, and
> many of the behavioral changes were confined to a fairly small part of it
> and were often themselves of relatively short duration - e.g. the armor
> worn by knights - so it is unsurprising that human genetics has not
> undergone rapid change during that time period.
>
> While somewhat older than 10,000 years, there is a very good recent
> example of what I would consider a Baldwin effect change in the human
> genome - namely the rapid acquisition of the ability to digest lactose in
> adult humans in several different populations of humans in northern
> europe and in africa. This came about because of the adoption of herding
> dairy animals by these populations, which suddenly made the ability to
> digest lactose as an adult a significant asset in surviving.
>
> And the evolution of language almost has to be a result of the Baldwin
> effect. Current homo sapiens have a "language instinct" - the ability to
> learn language is innate. But this can not always have been the case -
> earlier hominids must have had to teach their children how to
> communicate, gradually turning the indexical verbal and gestural signals
> of apes into a pidgin language that then became partly genetic until it
> evolved into a fully symbolic system of communication.
>
> Yours,
>
> Bill Morse
>
The thing about the BE is that we might not recognise one when we saw it.
Consider the following fictional story: About 5000 years ago people began to
farm cattle for milk, but bovine milk is often indigestible to humans due to a
long-chain molecule lactose. Nevertheless it is a rich renewal resource of
protein and energy. So some societies manage to figure out how to make it
digestible with the use of bacteria and heat. This makes dairy products a
fitness peak.

A mutation arises which makes people less intolerant of bovine long-chain
lactose. This mutation "encounters" a fitness landscape in which the ability
to digest *all* kinds of milk-products is very fit indeed. So that mutation
spreads, supplanting to a degree the learned cultural behaviours.

Is that not a BE? But would we recognise it as such or just say that the
lactose-tolerance mutation is fitter, not noticing that it is fitter because
of prior cultural knowledge?

--
John S. Wilkins, Postdoctoral Research Fellow, Biohumanities Project
University of Queensland - Blog: evolvethought.blogspot.com
Nihil tam absurdum quod non quidam Philosophi dixerit - adapted from Cicero

.

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