Re: Bipedalism and theorizing... was Re: Morgan and creationists
John Waters (jdwaters@dircon.co.uk)
22 Sep 1996 09:30:00 GMT
Paul Crowley <Paul@crowleyp.demon.co.uk> wrote in article
<843307169snz@crowleyp.demon.co.uk>...
> In article <01bba692$79401720$1d2470c2@jdwaters.dircon.co.uk>
> jdwaters@dircon.co.uk "John Waters" writes:
>
> > 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.
>
> 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.
>
> > This gave it greater endurance, and
> > the ability to traverse longer distances on a reduced
quantity
> > of food.
> >
> > The potential disadvantage of this development was the
increase
> > in the period of infantile helplessness after birth.
>
> I would not accept this at all. 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.
> I can see no reason why brain (or other skull)
> development could not be postponed till after birth.
JW: Nor can I. It would be.
> 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.
> > The more slowly developing infants then grow to adulthood in
the
> > normal way. However, because they have a better power to
weight
> > ratio, they are more likely to survive in times of drought
etc.,
> > when there is a premium on extra endurance.
> Even if we allow that there was a compelling adult need for a
better power/weight > ratio (and I don't) there is no
necessary effect on infant altriciality.
JW: True, but there would be if there was a change in the head
to body ratio.
>
> > Of course, if the climatic conditions are very severe, the
rate
> > of evolution can be much faster.
>
> I'm afraid this is nonsense. They just die faster. That's
all.
JW: We are at crosspurposes again. I am talking here about long
term genetic evolution, as the preceding sentance makes clear.
The rate of long term genetic evolution is often directly
related to the rate of long term global changes of climate. Long
term in this context can mean 100,000 years or 200 Mys, for
example.
>
>
> 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. 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.
Chimpanzees and Gorillas are social creatures, who support each
other. They are particularly supportive of nursing females. If
the ancestor ape specie had a polygamic mating system, like that
of Gorillas, the nursing female would be protected by a large
dominant male.
John
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