Re: Bipedalism and theorizing... was Re: Morgan and creationists
Paul Crowley (Paul@crowleyp.demon.co.uk)
Sun, 22 Sep 96 20:04:35 GMT
In article <01bba868$284e35e0$1d2470c2@jdwaters.dircon.co.uk>
jdwaters@dircon.co.uk "John Waters" writes:
> Paul Crowley <Paul@crowleyp.demon.co.uk> wrote in article
> > In article <01bba692$79401720$1d2470c2@jdwaters.dircon.co.uk>
> > jdwaters@dircon.co.uk "John Waters" writes:
JW:
> > > The ancestor Apes food sources became much more
> > > scattered. The distances between food sources became longer and
> > > longer. The hominids' Ape ancestor adapted to the changes by
> > > improving its power to weight ratio.
PC:
> > This is an example of the "evolution forces" argument. It is a
> > common one, but it is still bad. What happened to all populations
> > of virtually all species living in the Sahara when the recent
> > dessication took place? Did they adapt to a drier climate? No,
> > of course not. They just died.
>
> JW: We seem to be talking at cross purposes here. I am talking
> about long term genetic adaption, something which occurs over
> many generations. You appear to be talking about short term
> behavioural adaption, which occurs within an individual's
> lifetime.
No. I am, of course, talking of long-term genetic adaptation.
This error of yours is important to correct because it's basic to
your theory. It's also very common. Think of chimpanzees just
south of the Sahara - the boundary has been there for millions of
years, sometimes much further north, sometimes further south.
The chimps on the boundary have been under constant pressure to
adapt to a drier habitat. They have not done so (for obvious
reasons). Now let's say that from 2 mya to 1 mya there was a
general trend towards dessication. IOW the boundary generally
moved south in that period. How would that have changed anything?
You'd have about the same number of chimps in any generation
exposed to the same pressures. IOW a period of climatic change
does *nothing* to "force" adaptation.
PC:
> > An extension of infantile
> > helplessness is so disadvantageous that almost any way around it
> > would be found.
>
> JW: As explained in my letter, there would be no initial
> disadvantage because the nursing female would stay in her
> birthing place for the first three days after giving birth.
You can break down *any* evolutionary development and say that the
change in each generation would be so insignificant that it would
have no disadvantageous effects. That's plain cheating. You have
to outline the countervailing advantages.
PC:
> > All the infant needs is the ability to hold on; that simple reflex
> > action is possessed by numerous species with small brains.
>
> JW: Unfortunately it needs more than this. In addition to any
> reflex action, it needs to be able to place its limbs in the
> correct position on its mother's body. This requires cognitive
> control by the brain; and this is precisely what a helpless baby
> has not got. Reflex action is not enough.
It's been a primate capacity for at least some 65 Myr (and probably
longer). Call it complex if you like. It was lost in the hominid
line, but not by accident or as a by-product of something minor.
PC:
> > Consider the advantages of the closely related mother with an
> > infant that could hold on in the normal primate ventral
> > position. She can "gallop" quadrupedally. She can dash through
> > relatively dense bush. She can scoot up a tree. Mothers with
> > helpless infants would get wiped out and be replaced by their
> > more effective quadrupedal cousins.
>
> JW: It is a question here of relative advantage over a very
> short timescale ( eight hours in our example). Apes cannot
> gallop.
Chimp mothers with infants attached often use a two-beat
"gallop", alternating between hind and forelimbs. It's fast.
> JW: The mother of the helpless infant would have the same
> degree of intelligence as current Chimpanzees. In other words,
> high intelligence. She would be cunning and resourceful. She
> would be inventive. She would be agressive. She would be a match
> for any male of the specie. And most important of all, she would
> not be alone.
Yes. But a chimp mother with a clinging infant would be about
ten times more effective. So why should this "crippled" hominid
evolve from much more effective apes?
Paul.
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