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

Len Piotrowski (
Mon, 26 Aug 1996 18:51:10 GMT

In article <4vlbqe$> (Bryant) writes:

>>By this stratagem, you've self-qualified for Gould & Lewontin's criticism
>>while claiming the contrary (!?!).

>Back up. You're confusing me.

>Gould & Lewontin claim that too many evolutionists see every single trait
>in an organism as an _adaptation_ (a result of evolution by natural

>I say they're mistaken in this generalization, that only some traits are

For instance, "sugar craving" and "jealousy?" 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?

>What of what I said in the quote above confuses this issue?

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.

>>>Some reasoning, however, should quickly suggest that glucose is an
>>>important limiting resource for us big-brained creatures,

>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." Your "reasoning" is
hardly sterling.

>During childhood (not to mention the last trimester
>of prenatal development), a *large* proportion of our metabolic expense
>is accounted for by the demands of the growing brain.

Brains are not made by sugar alone. Why not an "amino-acid craving," or
"enzyme craving," or "general organic molecule craving?" Just because the
object of a "sugar craving" happens to involve constituents that can play a
role in metabolism, doesn't establish adaptive necessity. You wonder at my
skepticism? What about "Maple Syrup craving," "honey craving," "baloney
sandwich craving," the "craving for kraut and brats?" Are all these
implicated in your general metabolic adaptionist theory for the growing brain?

>>>and that jealous
>>>behavior likely had fitness effects in our ancestors' lives.
>>Only imaginatively.

>If by this you mean we must extrapolate and imagine, of course that's

Sorry for the obscurity - I meant only in your imagination.

>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. But a simple mind experiment may help
you over this disarray: if all age and sex grades experience "jealousy" in
different ways and to different degrees (including none) how can you
demonstrate a differential pattern in it's distribution in various populations
that point to it's fixation through natural selection?

>>>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,"

>Whatever. It's the definition used by biologists around the world.

Well, the point was that your "definition" is not the one used by biologists
around the world precisely for my enumerated reasons. I quibbled with your
precision, in other words.

>>the process of 'passing along,' and what is meant by "subsequent generations."

>You've got to be kidding. Reproduction and "subsequent" are foreign
>concepts to you?!

No, of course not. Does "reproduction" mean "fitness" to you? Since 'passing
along' encumbers a process that is not all-or-nothing, your definition for the
un-initiated left much to be desired. As to "subsequent generations," the same
problem arises as to just what is meant - traits, individuals, populations,
species? To you this may be obvious. But "for lurkers & others" it's a
simplification that disguises complex mechanism. Just how do you pass along
jealousy to subsequent generations?

>>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

>This is silly.

About as silly as your hypothesis I would note. If there is no "sugar craving"
gene your thesis is worthless. If there is a "sugar craving" gene, there must
be one for maple syrup, honey, baloney, and kraut with brats. Either way,
it's a nice thought, but hardly convincing.

>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.

>Parsimony deserves some
>consideration, here, Lenny.

I thought that was true.

>What's the more fantastic assumption--mine,
>that there are brain development genes, or yours, that there are not
>because they're "hypothetical" and unidentified?!

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!



"If you can't remember what mnemonic means, you've got a problem."
- perlstyle