Re: An alternative to ST and AAT

Paul Crowley (Paul@crowleyp.demon.co.uk)
Tue, 29 Oct 96 21:17:57 GMT

In article <schmal-2810962239060001@ppp-14202.firstnethou.com>
schmal@firstnethou.com "T&B Schmal" writes:

> Paul@crowleyp.demon.co.uk wrote:>
> > the first bipedal hominids would have been less
> > effective at terrestrial progression than their quadrupedal
> > cousins.
>
> This seems to me to be a difficult thing to assert. Now, if we knew the
> sequence of changes and how long it all took, maybe. But as things now
> stand I think you've got a bit of a stretch, here, Paul.

I can't see the problem, Tom. Let's assume the LCA was a quasi-
chimp. (I think this is most probable, but much the same argument
would apply to other kinds of LCA.) Chimps can walk bipedally,
although they are not good at it and revert to quadrupedalism
whenever they need speed or endurance. If, for some reason, a
population of chimps began to walk bipedally 90% of the time
instead of, say, 10% and there was some selection for those that
were best at it, there would be many, many generations where the
regular chimps would still be far better at getting around, by
comparison with the bipedal population.

What's the alternative?
a> the first bipedal hominids would have been *more* effective
a> at terrestrial progression than their quadrupedal cousins.

Can you make a case for this?

Paul.