[extropy-chat] HISTORY: Solved & Unsolved Riddles

[CurtAdams at aol.com]

In a message dated 11/13/03 9:07:34, twodeel at jornada.org writes:

>After thinking a bit further on this, I find myself wondering if it wasn't
>just easier, once we left the trees for the savannah, to modify the
>hunched-over gait that tree-dwelling apes use into our full-fledged
>bipedalism, than it would have been to revert to the same full
>quadrupedality that the other savannah animals had. 

It's unclear that our ancestors *ever* knuckle-walked like apes.  
Our distant ancestors were gibbonlike and gibbons walk bipedally
(albeit not well) if they must.  All fossils ever found so far are of
creatures far more bipedal than current apes.  It may well be that
some of the "human" ancestors and relatives are actually predecessor
of modern non-human apes.  The robust australopithicenes in particalar
are astonishingly similar to gorillas and become more so over time.

Either the apes developed knucklewalking twice or the mutual ancestor
developed it and then we lost it.  2 changes either way; equally parsimonious.
Duplicated evolution in the apes is actually more plausible evolutionarily
- it requires only one, relatively constant, evolutionary advantage,
rather than the complicated changes to induce a reversal in the human
line.