Question: Population Bottleneck and "out of Africa"
- From: nospam@xxxxxxxxxx (Paul Ciszek)
- Date: Tue, 2 Oct 2007 13:08:26 -0400 (EDT)
The way the "out of Africa" theory has been presented to me, the flow
of genes is supposed to have always been one-way: Homo Erectus leaves
Africa and learns to survive in a variety of different places, but we're
descended from any of *those* Homo Erecti. Later, archaic Homo Sapiens
migrates out of Africa, but we're not descended from any of *those*
archaic Homo Sapiens, etc. This never seemed right to me; if we were
capable of travelling all over the world before we were even human, then
why aren't we descended from some of those travelling pre-humans? If
anything, natural selection should *favor* geographic mobility. Then
I read about the Toba catastrophy hypothesis in Wikipedia.
Quoting from the wiki entry: "genetic evidence suggests that all humans
alive today, despite their apparent variety, are descended from a very
small population, perhaps between 1,000 and 10,000 breeding pairs."
Let's leave aside for now the discussion of whether this is what
actually happened, and speculate that it did. If the number was toward
the low end, I assume that these 1,000 or so breeding pairs had to be
close enough to each other geographically that their families could meet
up in time to save each other from the effects of inbreeding. Now, my
question: Would a bottleneck event like that erase all genetic evidence
of previous geographical distribution, and produce the "Out of Africa"
effect? Of course all modern humans are descended from people who
migrated out of Africa 70,000 years ago--that's all that was left! If
cosmopolitan, globe-trotting pre-humans had, in previous millenia,
occasionaly returned to woo the naive, provincial gals back home, would
there be any evidence for or against this in the post-bottleneck genome?
Of course, this hypothesis could be supported or debunked by *other*
sorts of evidence, like distribution of tool innovations, but that is
more a topic for sci.anthro.paleo.
--
Please reply to: | "Any sufficiently advanced incompetence is
pciszek at panix dot com | indistinguishable from malice."
Autoreply is disabled |
.
- Follow-Ups:
- Prev by Date: Article: Census of protein architectures offers new view of history of life
- Next by Date: Re: Evolution increases the computational ability of organisms.
- Previous by thread: Article: Census of protein architectures offers new view of history of life
- Next by thread: Re: Question: Population Bottleneck and "out of Africa"
- Index(es):
Relevant Pages
|
Loading
