East side story (was Re: The straw man.)

8 Nov 1995 21:05:39 GMT

Alex Duncan (aduncan@mail.utexas.edu) sez:
`In article <47qcd3$jlg@news.cc.ucf.edu> Thomas Clarke,
`clarke@acme.ist.ucf.edu writes:

`>By the way, what's the official PA line on the so-called
`>"West Side Story" - hominid, pongid speciation caused by geographic
`>isolation of the African Rift?

`It's been a long time since I read the article you mention. However,
`geographic isolation of protohominids from proto-African apes has long
`been a part of most models that attempt to account for the initial
`speciation event. If African rifting can supply an isolating mechanism,
`then I suppose it's plausible. My one concern with the idea is that our
`picture of early hominid geographic range is severely biased by the fact
`that most early hominid fossils are associated with the rift, which
`provided both a good depositional environment for the preservation of
`fossils, and a nice landscape for their eventual discovery. I suspect
`that the true ranges of the earliest hominids were much broader
`geographically. The rift valley provides us with a very small window on
`what was really going on.

My read on the article was that it didn't propose the Rift to be
a geographical barrier to apes, but rather that the climate
to either side of the rift diverged, with gallery forrest
persisting to the west, where chimps are found, but giving
way to savannah on the east, where hominids appear. Thus
an initially homogeneous population was suddenly provided
with two diverging environments emerging in its range, and
the population then diverged to accomodate the event.

vincent@triumf.ca <== faster % Pete Vincent
vincent@freenet.vancouver.bc.ca % Disclaimer: all I know I
% learned from reading Usenet.