Darwin-L Message Log 7:52 (March 1994)

Academic Discussion on the History and Theory of the Historical Sciences

This is one message from the Archives of Darwin-L (1993–1997), a professional discussion group on the history and theory of the historical sciences.

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<7:52>From lgorbet@mail.unm.edu  Wed Mar 16 23:17:48 1994

Date: Wed, 16 Mar 1994 22:17:48 -0700
To: Darwin-L@ukanaix.cc.ukans.edu
From: lgorbet@mail.unm.edu
Subject: Re: Humanoid fossils in Time

Maybe I'm *really* missing something, but the "single vs. multiple origins"
question seems to be being discussed as though the options were

  (a) whatever mutations were necessary to get to _sapiens_ from _erectus_
all occur in one place and then spread; or

  (b) all these things happened independently at a number of spatially (and
somewhat genetically) separated places.

An option that intuitively seems at least worth serious consideration is
what I *think of* as a variant of (b)---that at least some mutations
happened only at one or very few places, but that different critical
mutations happened at *different* places, so that the gene flow (that
resulted in _sapiens_ all over) was critically multidirectional.

Thus _sapiens_ would not have evolved at a single place, but the same
mutations and evolution would not have to be happening independently at
multiple locations either.  In principle, it might have even been critical
for our eventual evolution that *different* evolutionary events were
occurring initially independently, in that the chance for various parts of
the puzzle to get established might be greater in some environments than in
others and perhaps in the absence of interactions with other changes
happening elsewhere.

The picture I imagine is one whether some gene flow but not a lot enables
"enough but not too much" differences to develop for a while.  Later, some
of these changes perhaps increase the range of environments which can be
effectively utilized (and maybe populations), so that the rate of gene flow
increases "before it's too late".

Maybe this is all old hat and maybe it's based on fundamental
misunderstandings on my part.  I'd be curious to get feedback from those of
you who know what you're talking about...  Thanks.

Larry Gorbet                         lgorbet@mail.unm.edu
Anthropology & Linguistics Depts.    (505) 883-7378
University of New Mexico
Albuquerque, NM, U.S.A.

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