Re: New Detailed Chimp/Human DNA Analysis Clouds Split Scenarios


"deowll" <deowll@xxxxxxxxxxxxx> wrote in message
news:_4Ocg.375$dY4.68@xxxxxxxxxxxxxxxxxxxxxxxxx

"Chapstick" <chapstick@xxxxxxxxx> wrote in message
news:lpscg.17274$Lg.1474@xxxxxxxxxxxxxxxxxxxxxxxxxxx

"deowll" <deowll@xxxxxxxxxxxxx> wrote in message
news:Coubg.51039$iB2.35158@xxxxxxxxxxxxxxxxxxxxxxxxx

"Rich Travsky" <traRvEsky@xxxxxxxxxxxxxxx> wrote in message
news:446C84CB.397228AF@xxxxxxxxxxxxxxxxxx

http://news.bbc.co.uk/1/hi/sci/tech/4991470.stm

Humans and chimpanzees may have split away from a common ancestor far
more recently than was previously thought.

A detailed analysis of human and chimp DNA suggests the lines finally
diverged less than 5.4 million years ago.

The finding, published in the journal Nature, is about 1-2 million
years
later than the fossils have indicated.

A US team says its results hint at the possibility that interbreeding
occurred between the two lines for thousands, even millions, of years.

This hybridisation would have been important in swapping genes for
traits
that allowed the emerging species to survive in their environments,
explain the scientists affiliated to the Broad Institute of MIT and
Harvard
and the Harvard Medical School.
...
"This is a hypothesis; we haven't proved it but it would explain
multiple
features of our data," said David Reich, assistant professor of
genetics at
the Harvard Medical School and an author on the Nature paper.

"The hypothesis is that there was gene flow between the ancestors of
humans
and chimpanzees after their original divergence.

"So, there might have been an original divergence and a separation for
long
enough that the species became differentiated - for example, we might
have
adapted features such as upright walking - and then there was a
re-mixture
event quite a while after; a hybridisation event," he told the Science
in
Action programme on the BBC World Service.
...
The US investigation indicates the human and chimp lines split no more
than
6.3 million years ago and probably less than 5.4 million years ago.
...
Commenting on the research, Daniel Lieberman, a professor of biological
anthropology at Harvard, told the Associated Press: "It's a totally
cool
and extremely clever analysis.

"My problem is imagining what it would be like to have a bipedal
hominid and
a chimpanzee viewing each other as appropriate mates, not to put it too
crudely."


http://www.chron.com/disp/story.mpl/nation/3871353.html
One of the most detailed comparisons yet of human and chimp DNA shows
that
the split between the two species was a long, complicated affair that
may
even have featured an evolutionary version of breakup sex.
...
... The researchers, from the Broad Institute of MIT and Harvard,
propose
that humans and chimpanzees first split up about 10 million years ago.
Then,
after evolving in different directions for about 4 million years, they
got
back together for a brief fling that produced a third, hybrid
population with
characteristics of both lines.

That genetic collaboration then gave rise to two separate branches -
one
leading to humans and the other to chimps.
...
When the scientists at the Broad Institute compared the genes of humans
and
chimps, they found one of the chromosomes - the female sex chromosome
known
as X - was 1.2 million years younger than the others. It appeared the
two
species shared a common ancestor who gave them their X chromosomes and
did
so more recently than the ancestors who gave them the other
chromosomes.

The best explanation for this, the scientists think, is that ancient
humans
and chimps broke away from each other not once, but twice. The first
time
was more than 6.3 million years ago. The second time was at least a
million
years later.

What probably happened was some of the evolving human ancestors bred
with
evolving chimpanzees. This was perhaps not as weird as it seems, for
though
there were some physical differences between the two groups, "the early
humans must have looked pretty much like chimpanzees," said James
Mallet, a
geneticist at University College in London not involved in the new
research.
...

Let's be honest. Some guys just aren't all that picky. If its a
female... Heck some guys don't even draw the line there. As I once read
some guys would do it with a broken wine bottle as long at they can get
the appropriate parts to fit.



while i essentially agree with you... i am "stuck" on the image of the
modern chimp that ate the face off the guy that had raised him since
little baby chimphood. you know.. that accident that occured about a
year ago... tragic! geeish!

so, how can we use our best kinsey-master's and johnson research info and
imagine a mating between these two species? were they even "separate" at
that point? isn't there sufficient genetic research to state that a
population must have a minimum number of males (ie, a minimum number of
matings) in order to propagate it's line? (rather than die out).

to state my question differently: say, 9 millon years ago, chimps and
future-hominds split... geographically or whatever... and lead separate
lives for three million years or so. They come back together and live
happily for a few thousand years... raisin' kids and bein' happy. and
then are split again and a mere 6 million years later... it's us and them
baby cakes!

I can't imagine mating with a female chimp and not losing a vital part or
two.

--chap


Actually one female chimp raised in one of the early language experiments
thought guys were cute. However the difference between a chimp and 6
million years BP human ancestor weren't all that great so get over it.


<smile> i'm over it.. but can she handle the loss?!?

seems to me then that we were not two separate species at 6 mya. When DID
we pop up with an extra two chromosomes anyway?!?

and, if we're talking about sexual selection, it is not clear to me that in
hss it is the male that chooses.... but that is perhaps the subject of a
different thread.

--chap


.

Relevant Pages