Hair DNA reveals 2 migration waves out of Africa

http://www.sfgate.com/cgi-bin/article.cgi?file=/c/a/2011/09/23/MNBJ1L7NSO.DTL


Hello Patty, hope you're doing well and getting some flying in. Saw this
article and thought you might enjoy it. Take care, Morris
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Friday, September 23, 2011 (SF Chronicle)
Hair DNA reveals 2 migration waves out of Africa
David Perlman, Chronicle Science Editor


Long, long ago, a bold race of early modern humans left Africa and
migrated across vast stretches of southern Asia to Australia - a mass
migration of humankind that was followed thousands of years later by a
second wave of African migrants who would settle all of Europe and the
northern reaches of the Eurasian continent.
This new tale of humanity's movements out of Africa and around the world
comes from an international team of geneticists who report they have
traced the record of that first migration by sequencing the DNA from a
single lock of hair of an unknown Australian Aborigine that had lain for
nearly a century in a British museum.
The scientists maintain that instead of one human wave out of Africa, as
has been traditionally believed, there must have been two. The first
migration across southern Asia established the first Australians, the
continent's Aboriginal population; the second migration, much later, saw
modern humans, and, for a while, the Neanderthals, spread all across
Europe and ultimately Asia.
That earlier migration took place more than 70,000 years ago, according to
the geneticists, placing it at least 24,000 years before the second wave
of humans that would later populate Europe, Asia and, eventually, America.
Travel mode mystery
Although the numbers are imprecise, the findings seem to confirm what
archaeologists have long maintained: that the ancestors of today's
aboriginal Australians arrived there some 50,000 years ago - although how
they got there despite many ocean barriers remains a mystery.
A report on this elaborate feat of genetic detective work was published
online Thursday in the journal Science Express by a group of nearly 60
scientists led by geneticists Eske Willerslev and Morten Rasmussen of the
University of Copenhagen.
The original work determining the sequence of DNA in the aboriginal hair
was accomplished by Danish and Chinese scientists at their joint genomics
center in Shenzhen, China, and was compared with DNA sequences from 79
individuals from Asia, Europe and Africa. The results were then sent to a
group at UC Berkeley's Center for Theoretical Evolutionary Genomics.
There Rasmus Nielsen and two others in his lab, Yong Wang and Kirk
Lohmueller, analyzed and confirmed the DNA sequences, focusing on the DNA
obtained from the Aborigine's lock of hair.
Sequencing stretches of DNA in the human genome has long been possible,
and scientists can now read the chronological record of human evolution,
ethnic relationships and even the history of human epidemics by probing
human genes.
"Studying DNA can let you go back for hundreds and hundreds of
generations, and, after many complex computer simulations, we have strong
statistical evidence that makes us pretty confident that the story of the
first major human dispersal is correct," Nielsen said. Brewing controversy
The finding is bound to stir up controversy among many anthropologists and
archaeologists who have argued that there was only one wave of human
migration out of Africa and that it took place over a long period that
began some 60,000 years ago.
"The results they provide are pretty substantial, but I wish they had more
evidence," said Richard G. Klein, an eminent anthropologist at Stanford
who has long studied the movements of early modern humans and who is not
part of the Danish-led team.
Scientists generally agree that the aboriginal people of Australia arrived
there about 45,000 years ago. In a letter to reporters, Klein said, "I
think it's reasonable to suppose that the founding population reached
Australia before Eastern and Western Eurasians diverged, and this could
imply at least two Out-of-Africa expansions."
But a major problem, he said, is how the first Australians reached the
continent across a string of Southeast Asian islands and at least 30 miles
of open ocean.
There is no archaeological evidence there for boats of any kind, Klein
said. Additionally, he added, those first Australians arrived there with
only the most crude primitive stone tools similar to those found in
Southeast Asia from many millennia earlier.
The lock of aboriginal Australian hair that was the key to the study had
been collected nearly 100 years ago by an unknown British anthropologist
in the southwest Australian mining town of Kalgoorlie.
It remained lying in a succession of Cambridge University museums until
Willerslev and his colleagues used it with the permission of the
Goldfields Land and Sea Council, the representatives of Kalgoorlie's
modern aboriginal population. E-mail David Perlman at
dperlman@sfchronicle.com. ----------------------------------------------------------------------
Copyright 2011 SF Chronicle