Re: Evolution, "adaptation", and what's currently adaptive
Len Piotrowski (lpiotrow@magnus.acs.ohio-state.edu)
Tue, 27 Aug 1996 13:57:53 GMT
In article <4vt61j$q5m@argo.unm.edu> mycol1@unm.edu (Bryant) writes:
>[snip]
>>For instance, "sugar craving" and "jealousy?"
>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.
>>Let's say that Bryant claims
>>that these "traits" are " an _adaptation_ (a result of evolution by natural
>>selection." How do you claim to be a non-adaptationist by this process?
>I never claimed that I don't subscribe to the adaptationist program.
Well, that's all I was pointing out. Why all the hoopla?
>I
>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! 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
stance.
>>There is no confusion. You pick a behavior and concoct an adaptionist
>>explanation for it. I'm just pointing out the obviousness of it. Somehow you
>>think you're exempt from an adaptionist's critique _because_ of it.
>Nope, you've just misconstrued the nature of the debate between Gould and
>adaptationists.
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).
>>>>>Some reasoning, however, should quickly suggest that glucose is an
>>>>>important limiting resource for us big-brained creatures,
>>>>
>>>>Hardly.
>>
>>>This isn't a very productive critique. What about our brains' glucose
>>>metabolism suggests to you that dietary sugars weren't important during
>>>our evolution.
>>
>>Whether big brain, small brain, or no brain, "sugar craving" may or may not
>>have anything to do with "our brains' glucose metabolism."
>Indeed. Parsimony and inference were used on my end. Big brains do, by
>the way, consume more glucose. So do the brains of folks with higher IQs.
Whether or not your first assertion is true, I have no way of evaluating.
However, "sugar" is not the only means of obtaining glucose. As far as I am
aware, other carbohydrates are "consumed" by Big brains as well. Your
parsimonious logic would have to infer other forms of carbohydrate craving
too. I would think it would be just as likely that Big brains and folks with
higher IQs would consume tomatoes as opposed to sugar using your own method of
parsimony and inference. As to the implication, perhaps unintentional, that
Big brains correlate with higher IQs, I would disagree.
>We also have special sugar receptors on our tongues, remember. That's an
>interesting design feature for mere genetic drift to have placed upon our
>tongues, eh?
I don't know how "special" these receptors are, but they are not the only
ones, and I wouldn't suppose they are somehow linked to a "special"
constellation of brain genes. Do you think when your dog craves a sweet it's
somehow related to IQ?
>>>What *is* your point? That jealousy didn't inspire fitness
>>>effecting behaviors? That, too, would involve imagination. So what?
>>
>>So, that's an effective counter to your assertion. Why pursue it if you
>>believe the contrary can also be true.
>You, not I, rejected the use of imagination in evolutionary biology.
I think the proper test would be the scientific method, eh? If you think that
implies my rejection "of imagination in evolutionary biology" so be it. But
that's beside the point - you've presented two contradictory motives for your
"jealousy" trait, a balance which I thought was missing from your original
adaptionist presentation. This is a problem, I believe, that was pointed
out by Gould & Lewontin, to which you originally found some exception. I
believe this reflected some inconsistency on your part.
>>>>>[snip]
>And I quibble with your inaccuracy, here. This definition is indeed the
>one used by biologists around the world.
Indeed, a biologist may have recognized what you were attempting to say, but
I doubt your "lurkers" had a clue.
>>>[snip]
>For the reasons I stated in my previous post (and which you erased),
Double check yourself, Bryant. I erased nothing in my response - you've
selected what you thought was important to respond to in your previous post.
I've kept each of your responses intact, in total. I've noticed, however,
you've "erased" those parts of my last post to which you don't wish to address
- double standard here? I would suggest your critique of Gould & Lewontin and
subsequent presentation of adaptionist hypotheses reflect this same kind of
standard.
>this
>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.
>>>We don't know the location of even one of the genes which
>>>code for the development of the human brain, or heart.
>>
>>You'll have some trouble there, eh?
>>
>>>Are you saying
>>>that there are no genes for these traits?
>>
>>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
phenotype."
>>So, let me get this straight. Your ' "hypothetical" and unidentified'
>>evolutionary traits (sugar craving and jealousy) are more believable as the
>>result of adaptive selection for "brain development" because - they are
>>' "hypothetical" and unidentified?!' Boggles!
>Boggles indeed. You misread my sentence, somehow. You said that the
>lack of molecular genetic data about a given trait renders speculation
>about its evolutionary origins moot.
Not so. That's what you would like to understand. I've just suggested that
your functional adaptionist perspective may not be an absolute explication
of your two examples and is incongruous given your position on Gould &
Lewontin.
> I said that this reasoning leaves
>hearts and brains in the same boat, because we don't know exactly which
>genes code for these traits.
If you've made some functional adaptionist explanation for hearts and brains
in some such manner as your "explanation" for sugar craving and jealousy, you
might be right!
Cheers,
--Lenny__
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