Re: Evolution, "adaptation", and what's currently adaptive
Len Piotrowski (lpiotrow@magnus.acs.ohio-state.edu)
Fri, 6 Sep 1996 13:25:04 GMT
In article <50mva9$11ou@argo.unm.edu> mycol1@unm.edu (Bryant) writes:
>[snip]
>>If they have no function, how can you tell they were adaptations?
>Ask Gould. They're a theoretical construct, a thought experiment, meant
>to illustrate the fallacy of current adaptiveness Gould sees so pervasive
>in adaptationist thinking.
I thought I was asking a self-identified adaptationist about it. If
adaptations are simply unsupported theoretical constructs, wouldn't you agree
they are indeed fallacies?
>>>They are adaptations--just outdated ones,
>>>or ones being used in novel ways that weren't originally selected for.
>>
>>If they have a function, then by definition they are adaptations, not
>>exaptations, neh?
>It's semantics. Gould says no, that adaptations only count as such if
>they have current utility. Adpatationists, or many of them, say that to
>the contrary, if selection shaped a trait for a given task (even if it no
>longer serves that 'purpose' in the current environment), it is an
>adaptation 'for' that task.
The thought experiment is only asserted as true. Dreaming up a possible
function and then an environment in remote time to operate within is a fantasy.
>That's what I tried to communicate earlier: *If* sugar craving were an
>adaptation by the latter definition--a trait that spread throughout a
>species to encourage seeking out a limiting resource--it can be called
>one today, even though readily available sources of sugar make it a
>threat wrt tooth decay and obesity. Hence, what is adapted (adaptations)
>need not be adaptive currently.
If "sugar craving" is a phenomenological characteristic of the current
cultural setting, then it has no adaptive advantage by either definition.
>At least, that's my understanding of this.
In other words, potentially anything you can label a "trait" can be justified
as having an adaptive function sometime in it's ancestral history. Nice
closure for the sociobiological paradigm, but not very convincing otherwise.
Cheers,
--Lenny__
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