|
|
Re: Evolution, "adaptation", and what's currently adaptive
Len Piotrowski (lpiotrow@magnus.acs.ohio-state.edu)
Wed, 4 Sep 1996 14:51:02 GMT
In article <susansfDwzI0s.5Ap@netcom.com> susansf@netcom.com (Susan S. Chin)
writes:
>[snip]
>My understanding of Gould's critique of adaptationists can be related to
>his concept, presented with Elisabeth Vrba in 1982, of "exaptations."
[snip]
>I don't know if that helps either side of the discussion, but the concept
>of exaptations does eliminate the need to explain every currently
>"adaptive" (functionally useful) feature as having historically originated
>and evolved due to selection pressures for that current use. Theirs is a more
>narrowly delineated concept of what an adaptation is. Just because
>something is adaptive today, doesn't necessarily mean it evolved via
>natural selection for that reason. When it comes to features, it's not
>necessary to explain all functionally significant characters as products
>of natural selection in Gould & Vrba's more narrowly defined
>adaptationist view.
>Sorry if I'm being a bit redundant in the last paragraphs. But these
>concepts are not always easy to discuss, much less explain coherently.
Thanks, Susan, for reminding me about that term. In my own crude way I was
trying to make a similar point with my criticism of the process of functional
explanations. Would be hard to juxtapose purpose for a "trait" to account for
it's origination if "purpose" doesn't appear until some future date. You would
have to presuppose some form of directed selective force and an agent to apply
the selection, practicing outside the realm of nature yet itself the product
of natural selection (evolution of a system for self-behavioral
re-organization?!).
At any rate, does the concept of exaptation make all adaptations suspect as
pre-suppositions of a "purpose?"
Cheers,
--Lenny__
|