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Re: Evolution, "adaptation", and what's currently adaptive
Len Piotrowski (lpiotrow@magnus.acs.ohio-state.edu)
Fri, 23 Aug 1996 18:08:42 GMT
In article <4vkf6s$3d1i@argo.unm.edu> mycol1@unm.edu (Bryant) writes:
>[snip]
>>
>>I suppose by asserting a "jealousy instinct" and "sugar craving" that you
>>have, by some slight of hand, explicitly demonstrated the evolutionary
>>significance of these "behavioral traits" for some purported ancestral human
>>population.
>I have not, of course. As should be obvious, explicit demonstrations of
>the fitness effects of a given trait to our ancestors is quite impossible.
>It would be equally impossible to demonstrate explicitly that the human
>heart increased ancestral fitness.
By this stratagem, you've self-qualified for Gould & Lewontin's criticism
while claiming the contrary (!?!).
>Some reasoning, however, should quickly suggest that glucose is an
>important limiting resource for us big-brained creatures,
Hardly.
>and that jealous
>behavior likely had fitness effects in our ancestors' lives.
Only imaginatively.
>By the way, for lurkers & others: "fitness" in evolutionary discussions
>means "reproductive success," or ~how many copies of ones genes get passed
>along to subsequent generations.
The number of "copies of ones genes [that] get passed along to subsequent
generations" is not an adequate definition of what "fitness" means because of
the ambiguity in the meaning of "genes," the process of 'passing along,' and
what is meant by "subsequent generations." Technically, if there were to be
found a "sugar craving" gene or a "jealousy" gene, "the fitness effects of a
given trait to our ancestors" would be a relative measure of the reproductive
success of individuals that possessed these "genes."
However, since no known individuals have ever, nor currently do, possess such
hypothetical "genes," they cannot simply be inferred to exist from "Some
reasoning," and thus become objects of evolutionary selection for adaptive
reasons in the past, merely to satisfy a functional explanation for their
purported occurrence in present populations, except by unsupported assertion of
course.
Cheers,
--Lenny__
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