Re: Joel and Bryant /talk/

Joel and Lynn Gazis-Sax (gazissax@best.com)
Sat, 24 Aug 1996 11:11:38 -0800

Bryant wrote:
>
> In article <32191CA6.4B6@best.com>,
> Joel and Lynn Gazis-Sax <gazissax@best.com> wrote:
> >Bryant wrote:
> >> >To the individual, the well-being is very important. [...]
> >> Yep, but not to evolution. If I get myself shot up trying to mate with
> >> another fellow's gal, I've just committed genetic as well as literal
> >> suicide.
> >[...]
> >> But taking that risk, if my mating instincts are genetically
> >> rooted, may have paid off *on average* during human evolution, such that
>
> >The two examples are contradictory, incidentally. If it is genetic suicide
> >for me to do it, then reproduction is impossible.
>
>
> Of course. I said that *if* I got myself killed, I've committed genetic
> suicide. But risk-taking doesn't always entail failure, which is why it
> could stick around in a population despite potentially lethal outcomes.

No problem with this.

> >> I was thinking specifically of Gould & Lewontin's 1979 paper, in which
> >> they assert that adaptationists see "function in all." That's simply not
> >> the position of any adaptationist I've ever read or heard of or heard
> >> speak, and counts, I think, as a straw-man created by Gould & Lewontin.
>
> >This is 1996. The situation in 1979 was maddeningly different. What I see
> >in many of your comments is that Gould's observations have been taken to
> >heart in the further development of the theory.
>
> No, I didn't mean that. Evolutionary biology has progressed without
> paying much attention to Gould. But what he has done is present the
> public with an inaccurate view of the field of evolutionary biology.

I think that it did pay attention to Gould! Why then all the articles
which have been published in various magazines criticizing him. Gould
does not sound like someone whose word has not been taken into account
at all by his peers.

As for what he has done, I think many of Gould's arguments are quite
valid. He has, among other things, questioned:

* The phylogenetic tree and the shoehorning of species which makes it
look as if every fossil we find is an ancestor of some living creature.
Common sense thinking about evolution should tell us that many of the
species we find in things like the Burgess Shale didn't lead to anything
at all! If we believe otherwise, then we are buying into the idea of
nature by design, with absolutely predictable results and a Biblical
view of Man as the End Result of Evolution. The game isn't over yet is
the point that Gould keeps making.

* The notion that natural selection is responsible for new species. I
simply ask this: when has natural selection led to the creation of new
genes? I will concede that it can create new species. Here's a hypothetical
example: Let's divide the pool of dogs into three groups: chihuahuas, Great
Danes, and everything else. Currently this is a single species with many
subspecies. Now, let's get rid of every dog in the pool that is not a Great
Dane or a chihuahua. Voila! We have two genetic pools which are incapable
of breeding with one another. In former days, there were many intermediaries
in the genetic pool, but they are gone now. Natural selection has created
two new species.

What it /did not/ create, however, were the genes that made the chihuahuas
small and the Great Danes big. How did these come about? Through mutation
and similar DNA level processes. The only way that natural selection could
come up with changes that turned one offspring somewhere back in the time of
the first mammals into a herbivore and another into a carnivore would have
necessitated some kind of Lamarckian instrument. And we all know that Lamarckianism
doesn't work.

Natural selection acts on populations, not on the genes. That's a point that
gets forgotten. It can determine how many of the herbivores and the carnivores
survive, which of the new models lives and which dies out due to its inferior
ability to compete, but it cannot make the changes itself. It can only take
what is already in the genes.

Gould calls natural selection a secondary process in evolution because it
does not cause the primary changes itself. It only takes what is there and
winnows out the bad. That's all. The real cause of change is mutation. That
is what works at the primary level.

Here's some evidence for this operation: Consider the massive species dieoffs
which occur every few thousand years. Towards the end of one of these, we find
that there is lots of diversity out there and extreme specialization to fit
into niches. Then something happens (currently that something is called "humanity"
:) ) and many species, except for generalists, die off. Then the process
starts all over again. How do generalists turn into specialists? How did the
Koala, a classic specialist which can dine on eucalyptus leaves which kill other
animals, get that trait which allows it to store the poison out of harms way?
How could natural selection /do this/? If you say that it happened because one
day a proto-Koala started munching on eucalyptus and began developing a resistance
to the poison which it passed on to its descendants, then you have slipped into
the error of Lamarckianism. What Gould simply points out is that somewhere in
the past a Koala ancestor got lucky: it developed a gene that let it eat the eucalyptus
leaves. And because there were lots and lots of eucalyptus around, it could
survive.

We've never seen a species emerge to my knowledge (breeds of dogs and pigeons
don't count as new species), but we can draw from Gould a reason for this:
competition for new species is very tough at this time. To succeed as a mutation,
you'd got to either fill an empty niche or you have to be better than what's currently
out there. In a time of massive ecological change such as this, fitness is
awarded to the generalists who have more options for survival. In time, though,
there's a likelihood as the number of species decreases that we /will/ observe
new species arising, seemingly out of nowhere. They will be the product of
genetic mutation. They will fill an empty niche (the easiest way to get started)
and increase and multiply. If the rate of species dieoff remains constant, I
dare to predict that scientists will see real life vindication of Darwin within
the next five hundred years. It won't be spectacular. It won't be much, but
it will be there and it will not be ignored.

Don't you want to be there to watch the Creationists squirm? :)

Regards,

Joel

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