Re: An alternative to ST and AAT

John Waters (
1 Nov 1996 08:20:55 GMT

Paul Crowley <> wrote in article
> In article
> "T&B Schmal" writes:
> > I think the *base* case is that as members of the LCA
gradually became
> > more bipedal they gradually became better at
terrestrial progression.
> > This seems like the simplest and most obvious place to
> But bipedalism and quadrupedalism are two completely
> kinds of progression. If you get better at one, you
> get worse at the other. A change from one to the other
> entail a deterioration (for at least ~100 Kyr).

JW: There would only be a deterioration if the LCA was
either wholly
bipedal or wholly quadrupedal. However, if the LCA had a
mosaic of
bipedal and quadrupedal characteristics, there would have
no deterioration.
> > The alternative hypothesis, that as members of the LCA
gradually became
> > more bipedal they gradually became worse(!) at
terrestrial progression,
> > needs to have the case made for it.

JW: I agree. I cannot see the reasoning behind the
that bipedal terrestrial progression should be innately
worse than
quadrupedal progression.
> Indeed! That's the whole mystery of bipedalism. It
should not
> have happened. It does need special justification -
> when you think of the mother/infant dyad. It did not
happen just
> because the vegetation got a bit thinner. This is the
> problem of human evolution.

JW: Why does bipedalism need special justification? It
happened in
Dinosaurs, Birds, Kangaroos and Hominids. So what? What is
big deal, Paul? The fundamental problem of human evolution
is not
that it happened, but that human beings cannot comprehend
how it

One day, someone will work it out. When that happens,
everybody will say that the process of human evolution is
And nobody will be able to figure out why it took so many
people so long to comprehend such a simple, obvious