Tuesday, September 27, 2011
Australian Aboriginal Migrations
We know that the first known presence of humanity in
is from 44,000 years ago and more controversially perhaps even 60,000 years
ago. After that carbon 14 work fails us. Australia
Work has now clearly shown us that the dingo arrived some 6000 to 8000 years ago coincidentally with a sharp uptick in technical skills. Yet the work quoted here is finding no creditable evidence of genetic markers able to isolate such an event.
The obvious explanation is that each arrival was originally small in numbers and what could survive in the prehistory would only be the tools themselves. The first intrusion was never followed up with successful contact and the tool kit simply stagnated.
The second contact was sufficient to introduce the dingo but not to provide a new thriving population. Tools however are quickly shared and traded and would have swiftly found their place in society.
It is not a tale of migration so much as of two successful contacts against many that simply failed. With odds likely that steep, it is no surprise that no migration was involved the second time aqround.
Australian Aborigine Hair Tells a Story of Human Migration
Published: September 22, 2011
A lock of hair, collected by a British anthropologist a century ago, has yielded the first genome of an Australian Aborigine, along with insights into the earliest migration from the ancestral human homeland somewhere in northeast
An international team has sequenced the genome of an Aboriginal Australian man, using a lock of hair found from the early 20th century.
The Aboriginal genome bolsters earlier genetic evidence showing that once the Aborigines’ ancestors arrived in
, some 50,000 years ago,
they somehow kept the whole continent to themselves without admitting any
The Aborigines are thus direct descendants of the first modern humans to leave Africa, without any genetic mixture from other races so far as can be seen at present. Their dark skin reflects an African origin and a migration and residence in latitudes near the equator, unlike Europeans and Asians whose ancestors gained the paler skin necessary for living in northern latitudes.
“Aboriginal Australians likely have one of the oldest continuous population histories outside sub-Saharan Africa today,” say the researchers who analyzed the hair, a group led by Eske Willerslev of the
of . Denmark
Dr. Willerslev is an expert at working with ancient DNA, which is usually highly fragmented. Use of the ancient hair reduced the possibility of mixture with European genes and sidestepped the political difficulties of obtaining DNA from living Aborigines.
The DNA in the Aboriginal genome, when compared with DNA from other peoples around the world, shows that when modern humans first migrated out of Africa the ancestors of the Aborigines split away from the main group very early, and before Europeans and East Asians split from each other, Dr. Eske and his colleagues write in an article published online Thursday in the journal Science.
They exclude an alternative possibility, which is that Europeans split first from Asians, and that people from the Asian group colonized
Based on the rate of mutation in DNA, the geneticists estimate that the Aborigines split from the ancestors of all Eurasians some 70,000 years ago, and that the ancestors of Europeans and East Asians split from each other about 30,000 years ago.
But the genetic data offers no information as to where these populations splits may have occurred, whether in
or even earlier, before the migratory group had left Africa.
“We can’t really put the geography in there,” said Morten Rasmussen, a member
of the team at the . Danish
Genetic dates are based on a mixture of statistics and best guesses, but the split times calculated by the Danish team are compatible with the more reliable archaeological dates, which record the earliest known human presence in
at 44,000 years ago. The Aborigines’ ancestors could have arrived several
thousand years before this date. Australia
The Aborigine occupation of
presents a series of
puzzles, starting with the nature of their stone tools. The early stone tools
found in Australia Australia are much
simpler than the Upper Paleolithic tools that appear in Europe
at the same era. “I don’t understand why they looked so primitive,” said
Richard Klein, a paleoanthropologist at . Stanford University
Primitive as the tools may be, the first inhabitants of
Australia must have possessed advanced
boat-building technology to cross from the nearest point in Asia to Sahul, the
ancient continent that included Australia,
New Guinea and until the rise
of sea level that occurred at the end of the last ice age, 10,000 years ago.
But there is no archaeological evidence for boats, Dr. Klein said. Tasmania
Despite the Aborigines’ genetic isolation, there is evidence of some profound cultural exchange that occurred around 6,000 years ago. The stone tools become more sophisticated, and the population increased. The Aborigines did not domesticate plants or animals, but a wild dog, the dingo, first appears in the archaeological record at this time. Researchers led by Peter Savolainen of the Royal Institute of Technology in Stockholm reported this month in the journal Proceedings of the Royal Society B that they had traced the spread of the dingo across the islands of the Pacific by analyzing ancient DNA in the bones of Polynesian dogs.
The dingo originated on the Asian mainland and became part of the Polynesian domestic menagerie along with the pig, the chicken and the rat. This ensemble had reached
by A.D. 1250. How the dingo arrived
is an “enigma,” Dr. Savolainen writes, because none of the other elements of
Polynesian culture are found there. Australia
Even stranger, dogs always travel with their masters, yet there is no sign yet of Polynesian genes in the Aborigine population.
is a forbidding desert, and this barrier may have been the downfall of most
invasions, whether of people or of animals, Dr. Klein said. The ancestors of
the Aborigines were lucky enough to find their way south, where there is more
vegetation, and the dingo is a skillful hunter, able to look after itself. But
this leaves unexplained the cultural changes that began around or shortly after
the dingo’s arrival. Australia
“Something remarkable happened in
6,000 to 4,000 years ago,
and it involved much more than the dingo,” Dr. Klein said Australia