Re: Bipedalism and other

Clara N. Fitzgerald (cfitzger@s.psych.uiuc.edu)
3 Jul 1995 20:58:21 GMT

j#d#.moore@canrem.com (J. Moore) writes:

>JM> >Some gorillas, various macaques and the proboscis monkey spend
>JM> >varying amounts of time in all those places, but show none of the
>JM> >supposed AAH adatations. They utilise common ape and monkey locomotor
I had heard that probiscus (sp?) monkeys had been picked up by fishing
boats significant distances from land. You're saying that oxygen bell of
a nose couldn't possibly have anything to do with swimming?
There is an extinct species of swamp ape ( oreosticios ??? ) that
apparently shows some skeletal adaptions for bipedalism.
The descended larynx arrangment in humans seems sufficiently dangerous
(choking hazard, and bypassing the preheating and filtering provided by
the nasal cavity) to require some extraordinary explanation. I'm not
convinced that language is sufficient. When actually swimming (putting
one's head under), breathing in through one's nose usually brings in some
water with the air (problem with small openings and surface tension);
the mouth doesn't have this problem; water can get into the mouth, but
isn't swallowed.

>JM> >Various environments have been suggested by different AAH proponents;
>JM> >all state that a major reason that these water environments were
>JM> >necessary for the evolution of bipedalism is to help support the body
>JM> >weight of the animal. Note that this necessarily means that the animal
You've got it backwards; it is suggested that some support for body weight
was required to allow bipedalism (before anatomical changes had occured),
and water would perform that function. If it was rather easy and very
beneficial for the ape to stand up, why haven't the chimps or baboons tried it?

>Pa> What are the real advantages of wading compared to quadrupedalism?
We assume he meant 'bipedal vs. quadrupedal wading', as your reply assumes.

>This is a false dichotomy, or what Bateson would call a "confusion of
>logical types"; "wading" and "quadrapedalism" are not, as you claim
>here, mutually exclusive. Monkeys and apes which do go into water most
>often do so quadrapedally.

>Pa> 1) Better vision across the surface of the water and back to land.

>If the water isn't over your head, you can see "back to land" just
>fine with your head at the surface of the water. On land, however,
>bipedalism for this purpose would be a huge advantage.
It it's clear or fairly shallow water, you can see the bottom (rocks,
etc) which you can't see if your eyes are at the surface. You could also
see fish, patterns of ripples (sharks, etc) and get a sense of the currents
Please support the opinion that a wider view across land is more advantageous
than a similar view across water.

>Pa> 2) Lower energy usage compared to swimming.
>Refs, please. I've always found walking through water to be
>energy-intensive, as water gives such much resistance. But please do
>provide the references which contradict this impression.
Consider energy per unit of forward motion. Swimming uses a lot of
energy moving water around, only some of which also moves the swimmer forward.

>Perhaps you could explain how the AAT-hominids defended themselves
>against fierce aquatic predators such as crocodiles and sharks.
Besides knowing what areas and times to avoid (I would suspect that
early morning would be fairly safe against crocodiles ???), it's probable
there were losses; the birthrate could have made up for them.
What's the total yearly loss of lives to shark and crocs?

>Jim Moore (j#d#.moore@canrem.com)

--

-Clara A. N. Fitzgerald     cfitzger@s.psych.uiuc.edu

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