Re: Evolution, "adaptation", and what's currently adaptive

Bryant (
28 Aug 1996 07:40:39 -0600

In article <>,
Len Piotrowski <> wrote:
>In article <4vt61j$> (Bryant) writes:
>>Yup, I'd bet these were shaped by selection rather than drift, because
>>they have fitness effects. In identifying adaptations, one looks for
>>design features that likely increased organismal fitness.
>You haven't identified an adaptation, so I guess you've lost the bet. Their
>"fitness effects" are only asserted.

Nope, they're probable for the reasons I described. It also seems
unlikely that sugar receptors on the tongue would have evolved by drift
(accident), which is the only viable alternative to a selective
(adaptationist) explanation.

Adaptations are traits shaped and retained by selection for their
fitness-enhancing benefits. Hence, eyes are adaptations for seeing. Fair

And sugar receptors on the human/primate tongue are reasonably described
as adaptations for detecting sources of sugar. And the sugar
appetite/reward system in the brain is probably an adaptation for
encouraging the consumption of sugar, a limiting resource.

>>claimed that Gould et al.'s characterization of the adaptationist program
>>is exaggerative and inaccurate.
>... and yet, as you apparently admitted above, this accurately describes your
>own point of view!

Um, you're reading a different thread than I am. I just said that his
characterizations are exaggerated. I do not "admit" that adaptationism
sees current utility in all traits. Or even optimality in the design of
most traits.

>However, when skepticism about your functional adaptationist
>explanation for "sugar craving" and "jealousy" is voiced, you apparently are
>quick to discredit non-adaptationist alternatives. A somewhat contradictory

Not at all, Lenny. As I've said: I'm an adaptationist. I do not object
to the belief that natural selection is a more powerful evolutionary
force than genetic drift. I do object to this stance being characterized
as Panglosian. Adaptationists are not *just* speculating about the
evolved functions of traits--they're testing their hypotheses!

>Whatever. Either you are what you claimed above ("I never claimed that I don't
>subscribe to the adaptationist program") or you shift your point of view as it
>suits you. You can't critique Gould & Lewontin's claim on the one hand as
>overstated, and yet deny the possibility of non-adaptionist explanations for
>your own examples on the other, except by assertion (parsimonious or not).

I don't "deny the possibility." Give me some reasonable alternatives for
the evolution of sugar-detecting taste buds on your tongue, Lenny. My
thinking that they are probably adaptations is not the same as asserting
that every trait has current and optimal utility.

In other words, for the zillionth time: I'm an adaptationist. YET
(jeepers!) I object to Gould's mischaracterization of adaptationism.

>>is silly. Your assertion would render nearly *all* thinking about ultimate
>>causation (be it about hearts or brains or tongues) utterly moot.
>I would disagree.

*HOW*?! You dismissed evolutionary speculation about traits for which we
don't have a genetic loci identified!

>>>The brain and heart are at least physical objects. "Sugar craving" and
>>>"jealousy" are somewhat problematical in this regard.
>>They, like behaviors, are outputs of physical phenotype (in the brain,
>>the tongue, etc.). Where's the problem?
>The problem is with your definition of human behavior as "outputs of physical

Sigh. OK. So this boils down to a duelistic/spiritualist interpretation
of the generation of behavior, then, Lenny?

I assert that the nervous system generates behavioral responses to
environmental cues. You seem to think that the nervous system is not