Re: Natural Selection (was: Breast Size)

Bryant (
12 Jun 1995 07:52:41 -0600

In article <3rg92j$>,
Phillip Bigelow <> wrote:
>I wrote:
>>> There is no "consciousness" to evolution. It is, instead, a never-ending
>>>process of RANDOM changes in morphology.
> (Bryan) writes:
>>Wrong. That's the grist of the process, not the process. Selection is
>>not random. Ultimately, the mutations on which it acts are, of course.
>>(You say as much in a snipped part of the post, later on.)
> I'm still unconvinced that the process of natural selection is driven "TO"
> "something".

Phil, I hate to argue semantics like this. But, I didn't say that
natural selection is driven "to" anything. I said that adaptations can
safely be referred to as functional--"opposable thumbs are for grasping."
That's all I've meant to convey in this thread.

>I'm not even sure that natural selection really "follows"
>rules of *any* sort. If, as you claim, natural selection is NOT a random
>process, then it should be relatively easy to test or to debunk.

If selection regimes were not to some degree "predictable" (meaning, they
stay constant enough for the genotypes that survived the last generation
to survive the next), life wouldn't have gotten very complex.

> You seem to be looking at natural selection mainly from the "winner's"
>point-of view. You are claiming that natural selection is purpose-
>driven because you see all of the success-stories. Reversed-claws on perching
>birds shows that natural selection pushed the change in morphology "TO" it's
>fruition. I don't think selection works that way.

You've lost me.

>Primates achieve the same grasping "goal" by using opposable thumbs.
>Oppossums achieve it by the use of a prehensile tail.
>I don't see a drive "TO" an optimum grasping body plan, here. I see
>randomness in morphology.

I didn't say anything about optimal solutions or "drives TO." You don't
see randomness, either, however. You see function constrained, perhaps,
by phylogenic baggage--you see different strategies for the same
functions because the species' ancestors had different structural fodder
to work with.

> Consider also that there are many losers in the
>natural selection process, too. If selection toward a specific
>morphology/lifestyle is "driven" in some way, then why should selection even
>bother to produce mutations that don't benefit the survival of the organism?

Um, mutations are random. Selection doesn't "produce" them. It acts on
them. The vast majority of mutations are deliterious or "neutral" and
are culled or not selected upon at all.

>evidence that, in natural selection, the effects of the process are
>random, just as much as the process, itself, is random.

No, no. MUTATIONS are random. Selection upon them is not.

> When we start talking about natural processes being driven "TO" something,
>we start to anthropomorphize those processes.

Indeed; that's why I avoid making such statements.
[accidental snip]
>for large brain capacity was random. Whether our intelligence
>is beneficial for the continued survival of our species...well..the jury is
>still out. That's probably a random process, too.

You seem to confuse mutation with selection; human brains are damned
expensive to build (about the third trimester, if I recall, is devoted to
enlarging body parts and building brain). If it hadn't conveyed fitness
advantages (ie, been selected for), those with smaller brains (lower
investments) would have invaded the population.