Re: Bipedalism and theorizing... was Re: Morgan and creationists
John Waters (jdwaters@dircon.co.uk)
2 Oct 1996 03:25:49 GMT
Gerrit Hanenburg <ghanenbu@inter.nl.net> wrote in article
<DyM45s.D0r@inter.NL.net>...
> "John Waters" <jdwaters@dircon.co.uk> wrote:
> >JW: This is very interesting. Are you saying that a
chimpanzee
> >(like Faben) with a paralysed arm could walk long distances,
> >but that a nursing female with a new born infant could not?
>
> >What are the extra requirements that such a female would
need?
>
> Jane Goodall:"Chimpanzees walk upright for a few yards when
their arms
> are full of fruit or when peering over long grass,but Faben
can
> maintain this stride for about thirty yards at a stretch."
> (National Geographic (1979) vol.155 nr.5,p.607)
>
> I hesitate to call thirty yards long distance,but I guess that
when
> Faben can do it,then a female chimp with an infant can do it
> too,although you must realize that the infant is an *extra*
eccentric
> weight unlike Faben's arm.
JW: Yes, I take your point about the extra weight; but a nursing
female has as much potential walking ability as an unencumbered
male. That's fine.
Incidently, in The Chimpanzees of Gombe the photographs on page
343 show an infant clinging (ventrally) to its mother, and
clearly clenching its hands and feet to grip its mothers
skin/fur. Paul is right when he says that the infant's arms wrap
round the mother, but nevertheless you are clearly right when
you say the infants fingers clench the mother's fur and skin.
> What I meant was that regular "genuine" long distance walking
(say 200
> yards or more) requires a reorganization of the pelvic region
and
> lower limbs.
> As you probably know,when chimps stand or walk bipedally,they
do so
> with flexed hips and knees in order to retain maximum lever
advantage
> for the hamstring muscles.This requires a lot of energy and
leads to
> rapid fatigue.
JW: I agree with all of this, but it seems to make Paul's
arguments concerning the putting down of the infant all the
stronger. If Faben could only manage thirty yards, how far could
a chimpanzee mother with a three year old infant manage? Thirty
inches?
> To change that,any chimp that aspires to become a
long-distance
> bipedalist should at least do the following:
> -extend the lower limb.
> -increase the angle between ilium and ischium.
> -develop a lumbar lordosis.
>
> Gerrit
>
JW: Right, and that is what the Hominids did. So can we now
consider (and hopefully agree) upon a general schema concerning
Hominids and Bipedalism?
I assume that you accept that the Hominids eventually became
fully bipedal, and that the Gorilla/Chimpanzee/Bonobo have two
types of ground level locomotion, namely: knuckle walking and
bipedalism. However, I am not sure where you stand on the other
aspects of the matter. Can we clarify a few things?
1. Do you accept that the Gorilla/Chimpanzee specie became
knuckle walkers after their collective split from the Hominids?
2. Using retrospective analysis, do you accept that before the
Gorilla/ Chimpanzee specie developed knuckle walking, their only
means of ground level locomotion was bipedalism?
3. From this, do you accept (by extension) that the common
ancestor of the Gorilla/ Chimpanzee and the Hominids was bipedal
on the ground?
4. By deduction, do you accept that the Hominids inherited
bipedalism as the sole means of ground level locomotion from the
common ancestor?
5. Do you accept that the Hominids were never knuckle walkers?
6. By extension, do you accept that Hominids developed from
short distance bipedal walkers to long distance bipedal walkers,
without any intervening quadrupedal stage of locomotion?
John
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