Re: Bipedalism and theorizing... was Re: Morgan and creationists

Paul Crowley (
Sat, 21 Sep 96 12:46:00 GMT

In article <01bba697$11cada80$> "John Waters" writes:

> An example of this was quoted by Jane Goodall in
> her book, The Chimpanzees of Gorme. In this instance, a male
> chimpanzee was affected by poliomyelitis. As a result, the
> Chimpanzee lost the use of his right arm. As the male normally
> moved on the ground by means of knuckle walking, it would be
> reasonable to assume that it would modify its approach by
> knuckle walking one handed. However, this did not happen.
> Instead, the Chimpanzee switched to bipedalism, and learned to
> walk considerable distances using this method.

Distances in the Gombe are relatively small. It would hardly
have worked in the chimp territories of say, Senegal, which are
much larger. Also Goodall paid staff to keep paths clear to
enable human observers to get around. Futhermore, Faben (the
chimp's name) did not have to carry young. A female chimp
with infant would find bipedal progression extremely difficult
if not impossible.

> From the point of view of predator avoidance, bipedalism would
> have clear advantages because of the increased elevation of the
> head and eyes.

If we're talking of a woodland habitat, this hardly counts.

> Furthermore, whereas with knuckle walking the Ape
> tends to look at the ground, with bipedalism the head can
> naturally scan the horizon for previously undetected predators.

The spines of knuckle-walking apes enter the skull towards the
back, so they naturally look forward at all times.

> In addition, a bipedal sprint would take the mother out of the
> danger areas more quickly that a single handed knuckle-walking,
> crawl.

And much less quickly than a quadrupedal ape with an infant in
the ventral position.

> Either way, the nursing females with the dependent infants would
> only have to make it to the nearest point of cover, or feeding
> place. Thereafter, within eight hours the infant would be no
> longer helpless, and the female could knucklewalk as usual.
> If the scenario of the bipedal sprint has any validity, then it
> would be normal for genetic evolution of improved bipedal
> characteristics to follow as a result of this behaviour.

First you posit (a) a compelling need for a better power/weight
ratio. This produces (b) a extension in infantile helplessness.
Then (c) a steady expansion of this is the driving force of
hominid evolution.

I'm afraid that I find each stage very dubious.