Modern Asians have African ancestors
The theory that the ancestors of all modern humans came from Africa received a boost on Thursday with the publication of supporting research.
Scientists based across Asia, in the US and the UK examined the Y-chromosomes of more than 12,000 people from across Asia and found no traces of any ancient non-African influence.
"This result indicates that modern humans of African origin completely replaced earlier populations in East Asia," the researchers write in the journal Science.
The main alternative explanation of human origins - that modern humans are descended from separate populations which developed in different places - is known as multiregionalism.
"This really puts the nail in the coffin of multiregionalism," R Spencer Wells, co-author of the research, told BBC News Online. The value of the new research lies in the scale of the project, he said. BBC: More...
Thursday May 10 9:29 PM ET
WASHINGTON (AP) - A new genetic study suggests that Asia was populated by modern humans who migrated from Africa.
The study, appearing Friday in the journal Science, supports the Out of Africa Theory that homo sapiens, which are modern humans, moved into Asia and replaced homo erectus, an earlier human species that also migrated from Africa to Asia.
Researchers tested more than 12,000 males in 163 Asian populations to search for three mutations on the Y chromosome. Every one who was tested carried at least one of the mutations.
If the mutation was not found, it would have suggested a more ancient origin, such as from homo erectus, the researchers said. But since all tests showed the mutation, it was evidence that the populations now in Asia came from a migration from Africa of modern humans and not from a mingling of modern humans with homo erectus.
The research supports earlier studies that also suggested that modern humans in Europe and Asia originated from people who originated in Africa and then migrated to the rest of the world.
Shriver warns, however, that there are some ways in which this result could be accurate, even though interbreeding took place. If all of the Y chromosomes inherited from Homo erectus were eliminated from the population because those with Homo erectus ancestors were swept from the population due to a disease to which they were especially susceptible, they would not appear in the sample. Also, if only Homo erectus women mated with Homo sapiens men, but no Homo sapiens women mated with Homo erectus men, then there would be no Y chromosomal evidence of the admixture.
While these possibilities must be considered, one of the strongest components of this study is its size. The 163 population samples came from populations in Central Asia, Central Siberia, Okhotsk/Amur, Kamchatka/Chukotka, Northern East Asia, Northern Han Chinese, Southern Han Chinese, Taiwanese Aborigines, Southeast Asia, Indonesia/Malaysia, Poly/Micronesia and Northeast India, covering a broad geographic area.
The large number of populations also eliminates the possibility that genetic drift is the cause of the researcher's results. Genetic drift is a tendency for small populations to gradually alter their genetic make up over time. The researchers find it hard to imagine that all the 163 populations should drift in the same direction. www.sciencedaily.com
Thursday May 10 3:49 PM ET
Study Backs 'Out-Of-Africa' Theory of Human Origin
September 30, 1998
DNA traces Chinese back to Africa
BBC May 11, 2000
Fossils may be 'first Europeans'
The Remains of what may be the earliest human ancestors to migrate from Africa into Europe have been found in the Republic of Georgia.
Two skulls, which are probably about 1.7 million years old. More...
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