From: Robert J. Bradbury (bradbury@aeiveos.com)
Date: Sun Mar 16 2003 - 05:38:03 MST
On Sat, 15 Mar 2003, Mark Walker wrote:
> If memory serves we split from the common chimp about 5 million years ago.
> If the difference between us is 5% does this mean that we differ about 2.5%
> from our most recent common ancestor?
It is probably doubtful that evolution split the genomic differences evenly
between us and the chimpanzees. It could easily be 4%/1% or 1%/4% depending
on the selection pressures. I'd lean more in the direction that humans ended
up with more of the differences since it would seem that chimps are fairly
well adapted to environments that existed 5 million years ago while humans
have clearly gone through one or more population bottlenecks where we had
to overcome some significant difficulties.
> Is there solid evidence to suggest that our genome differs more from
> our most recent common ancestor than chimps?
No evidence that I'm aware of other than that I cite above. We may know
a bit more once the chimp genome is done (we can see if there is perhaps
less genome rearrangement). I believe that a collection of Asian countries
have started sequencing the chimp genome so we may know in a few years.
Its going to be tricky however without the genome of one of those ancestors.
It might take doing a few other closely related primates to see if we can
get back to the prototype primate genome and see if we have diverged more
than some of the other primates.
Robert
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