Neanderthal genome inherited by humans, study says

Hi Ms Andrews Interesting stuff!
----------------------------------------------------------------------
This article was sent to you by someone who found it on SFGate.
The original article can be found on SFGate.com here:
http://www.sfgate.com/cgi-bin/article.cgi?file=/c/a/2011/08/26/MN971KQCVQ.DTL
---------------------------------------------------------------------
Friday, August 26, 2011 (SF Chronicle)
Neanderthal genome inherited by humans, study says
David Perlman, Chronicle Science Editor


SAN FRANCISCO -- It's a tale of romance from the Ice Age - and its
consequences today.
Long ago, in a part of the world now known as Europe, early modern humans
lived alongside the Neanderthal people - and they interbred.
A fast-growing population of humans eventually drove the Neanderthals to
extinction 30,000 years ago, but the benefits of those early dalliances
between the two groups live on.
The Neanderthals, it seems, passed on to humans many of the genes that now
mark our greatly improved immune systems, according to an international
team of researchers led by a Stanford group.
The researchers, deciphering the genome of fossil Neanderthals and modern
humans, report they have found in both a major group of matching immune
system genes - genes the scientists say we inherited from our stocky Ice
Age predecessors.
The same scientists also studied the genes of a different ancient people,
the Denisovans, who were contemporary with the Neanderthals and whose
meager fossils were found in a Siberian cave called Denisova. The
Denisovans, the Stanford scientists said, were likely a "sister group to
the Neanderthals" who apparently bequeathed genes of their immune systems
to modern Melanesians - the people of New Guinea, Fiji and scores of other
islands in the western South Pacific.
In a report published in the journal ScienceExpress on Thursday, Peter
Parham, a Stanford microbiologist and immunologist, describes how he and
22 colleagues from five nations traced the genetic history of the varied
people who originated in Africa and later moved into Europe and the Middle
East. Genomes decipherd
The German anthropologist Svänte Paabo and his colleagues first deciphered
the Neanderthal and Denisovan genomes and showed where and when they
interbred with modern humans.
The fossil record indicates that those ancient pre-human people apparently
left Africa some 400,000 years ago and roamed across Europe and Asia until
modern humans moved into their Eurasian turf from Africa around 85,000
years ago, and quickly replaced them, Parham said.
Homo sapiens overran the Neanderthals from Northern Europe to Spain, and
by 30,000 years ago the Neanderthals were gone. Similarly, humans also
overran the Denisovans in Siberia and they disappeared at about the same
time.
But some of their genes lived on in humans, Parham's team reported. They
were found in modern people in Europe, Asia and Melanesia, but not found
in African people, the researchers said. Bacterial protection
The parts of the modern immune system that come from the Neanderthals and
Denisovans are known as the HLA histocompatibility complex, a group of
protein-creating genes located on chromosome six that help protect humans
against assaults by some bacterial infections and viruses, and the
rejection of tissue transplants.
"All this tells us a lot about human history," Parham said. "We didn't
just replace the Neanderthals and Denisovans, we have retained some of
them in us. There was a lot of diversity in dealing with the pathogens
they faced, and we have that diversity too."
The report is likely to generate some controversy among geneticists.
Montgomery Slatkin, a UC Berkeley geneticist who was on Paabo's team,
commented cautiously.
He called the conclusions "plausible," largely because the HLA genes from
Neanderthals were found in Europeans but not in Africans. As to finding
Denisovan genes in modern Europeans, Slatkin said: "I am less convinced of
this, although their conclusion is not completely implausible."
He was more certain about the finding that the Denisovan immune system
genes exist in modern Melanesians.
"This evidence is the most convincing," Slatkin said. E-mail David Perlman
at dperlman@sfchronicle.com. ----------------------------------------------------------------------
Copyright 2011 SF Chronicle