Ada hal menarik nih, apa iya orang perancis lebih moderen (secara evolusi)
ketimbang papuan ?
Hmm sepertinya penduduk asli eropa (Neanderthal) pernah dihajar habis oleh
penduduk asli africa (Homo Sapiens).
RDP
http://news.bbc.co.uk/2/hi/science/nature/8660940.stm
Neanderthal genes 'survive in us'
[image: Human and Neanderthal interbreeding]
By Paul Rincon
Science reporter, BBC News
*Many people alive today possess some Neanderthal ancestry, according to a
landmark scientific study.*
The finding has surprised many experts, as previous genetic evidence
suggested the Neanderthals made little or no contribution to our
inheritance.
The result comes from analysis of the Neanderthal genome - the "instruction
manual" describing how these ancient humans were put together.
Between 1% and 4% of the Eurasian human genome seems to come from
Neanderthals.
But the study confirms living humans overwhelmingly trace their ancestry to
a small population of Africans who later spread out across the world.
*[Neanderthals] are not totally extinct, in some of us they live on - a
little bit*
Professor Svante Paabo
Max Planck Institute for Evolutionary Anthropology
The most widely-accepted theory of modern human origins - known as Out of
Africa - holds that the ancestors of living humans (*Homo sapiens*)
originated in Africa some 200,000 years ago.
A relatively small group of people then left the continent to populate the
rest of the world between 50,000 and 60,000 years ago.
While the Neanderthal genetic contribution - found in people from Europe,
Asia and Oceania - appears to be small, this figure is higher than previous
genetic analyses have suggested.
"They are not totally extinct. In some of us they live on, a little bit,"
said Professor Svante Paabo, from the Max Planck Institute for Evolutionary
Anthropology in Leipzig, Germany.
Professor Chris Stringer, research leader in human origins at London's
Natural History Museum, is one of the architects of the Out of Africa
theory. He told BBC News: "In some ways [the study] confirms what we already
knew, in that the Neanderthals look like a separate line.
"But, of course, the really surprising thing for many of us is the
implication that there has been some interbreeding between Neanderthals and
modern humans in the past."
Science Explained: What is a genome?
John Hawks, assistant professor of anthropology at the University of
Wisconsin-Madison in the US, told BBC News: "They're us. We're them.
"It seemed like it was likely to be possible, but I am surprised by the
amount. I really was not expecting it to be as high as 4%," he said of the
genetic contribution from Neanderthals.
The sequencing of the Neanderthal genome is a landmark scientific
achievement, the product of a four-year-long effort led from Germany's Max
Planck Institute but involving many other universities around the world.
The project makes use of efficient "high-throughput" technology which allows
many genetic sequences to be processed at the same time.
The draft Neanderthal sequence contains DNA extracted from the bones of
three different Neanderthals found at Vindija Cave in Croatia.
Retrieving good quality genetic material from remains tens of thousands of
years old presented many hurdles which had to be overcome.
The samples almost always contained only a small amount of Neanderthal DNA
amid vast quantities of DNA from bacteria and fungi that colonised the
remains after death.
[image: Svante Paabo with Neanderthal skull (Max Planck Institute)]
Svante Paabo (pictured here with a Neanderthal skull) led the research
effort
The Neanderthal DNA itself had broken down into very short segments and had
changed chemically. Luckily, the chemical changes were of a predictable
nature, allowing the researchers to write software that corrected for them.
Writing in Science journal, the researchers describe how they compared this
draft sequence with the genomes of modern people from around the globe.
"The comparison of these two genetic sequences enables us to find out where
our genome differs from that of our closest relative," said Professor Paabo.
*Those things that made the Neanderthals apparent to us as a population
- those things didn't work*
Dr John Hawks
University of Wisconsin-Madison
The results show that the genomes of non-Africans (from Europe, China and
New Guinea) are closer to the Neanderthal sequence than are those from
Africa.
The most likely explanation, say the researchers, is that there was limited
mating, or "gene flow", between Neanderthals and the ancestors of
present-day Eurasians.
This must have taken place just as people were leaving Africa, while they
were still part of one pioneering population. This mixing could have taken
place either in North Africa, the Levant or the Arabian Peninsula, say the
researchers.
Professor Stringer added: "Any functional significance of these shared genes
remains to be determined, but that will certainly be a focus for the next
stages of this fascinating research."
The Out of Africa theory contends that modern humans replaced local
"archaic" populations like the Neanderthals.
But there are several variations on this idea. The most conservative model
proposes that this replacement took place with no interbreeding between
modern humans and Neanderthals.
*Unique features*
Another version allows for a degree of assimilation, or absorption, of other
human types into the *Homo sapiens* gene pool.
The latest research strongly supports the Out of Africa theory, but it
falsifies the most conservative version of events.
The team identified more than 70 gene changes that were unique to modern
humans. These genes are implicated in physiology, the development of the
brain, skin and bone.
The researchers also looked for signs of "selective sweeps" - strong natural
selection acting to boost traits in modern humans. They found 212 regions
where positive selection may have been taking place.
The scientists are interested in discovering genes that distinguish modern
humans from Neanderthals because they may have given our evolutionary line
certain advantages over the course of evolution.
The most obvious differences were in physique: the muscular, stocky frames
of Neanderthals contrast sharply with those of our ancestors. But it is
likely there were also more subtle differences, in behaviour, for example.
Dr Hawks commented that the amount of Neanderthal DNA in our genomes seemed
high: "What it means is that any traits [Neanderthals] had that might have
been useful in later populations should still be here.
"So when we see that their anatomies are gone, this isn't just chance. Those
things that made the Neanderthals apparent to us as a population - those
things didn't work. They're gone because they didn't work in the context of
*our *population."
Researchers had previously thought Europe was the region where Neanderthals
and modern humans were most likely to have exchanged genes. The two human
types overlapped here for some 10,000 years.
The authors of the paper in Science do not rule out some interbreeding in
Europe, but say it was not possible to detect this with present scientific
methods.
*paul.rincon-inter...@bbc.co.uk* <paul.rincon-inter...@bbc.co.uk>
--
You can do hard way or you can do smart way ... both ways need you to do it
any way ... not just discuss it in the hall way.
