A new report confirms what I've been insisting on for a very long time now, that there is absolutely no support for multiregionalism in any shape or form, and all human populations outside of Africa are descended from a single small band of migrants who left the continent relatively recently.
By studying the DNA of an ancient people in Malaysia, a team of geneticists says it has illuminated many aspects of how modern humans migrated from Africa.
The geneticists say there was only one migration of modern humans out of Africa; that it took a southern route to India, Southeast Asia and Australia; and that it consisted of a single band of hunter-gatherers, probably just a few hundred people strong.
Because these events occurred in the last Ice Age, when Europe was at first too cold for human habitation, the researchers say, it was populated only later, not directly from Africa but as an offshoot of the southern migration. The people of this offshoot would presumably have trekked back through the lands that are now India and Iran to reach the Near East and Europe.
The findings depend on analysis of mitochondrial DNA, a type of genetic material inherited solely through the female line. They are reported today in Science by a team of geneticists led by Dr. Vincent Macaulay of the University of Glasgow.
With this approach, Dr. Macaulay's team calculates that the emigration from Africa occurred 65,000 years ago, pushed along the coasts of India and Southeast Asia and reached Australia by 50,000 years ago, the date of the earliest known archaeological site there.
Now, each base-pair has its own evolutionary history, so we can't rely completely on just what mtDNA is telling us, but given that this story is roughly in keeping with the tale told by the Y-chromosome, I think one can confidently say it's the right one. The only point of disagreement I'd have with this study is the migration date, which I think is at least 10,000 years too early, and I'm not alone in this regard.
There is no evidence of modern humans outside Africa earlier than 50,000 years ago, said Dr. Richard Klein, an archaeologist at Stanford. Also, if something happened 65,000 years ago to allow people to leave Africa, as Dr. Macaulay's team suggests, there should surely be some record of that in the archaeological record in Africa, Dr. Klein said. Yet signs of modern human behavior do not appear in Africa until 50,000 years ago, the transition between the Middle and Later Stone Ages, he said.
"If they want to push such an idea, find me a 65,000-year-old site with evidence of human occupation outside of Africa," Dr. Klein said.
Geneticists counter that many of the coastline sites occupied by the first emigrants would now lie under water, because the sea level has risen more than 200 feet since the last Ice Age. Dr. Klein expressed reservations about that argument, noting that people would not wait for the slowly rising sea levels to overwhelm them but would build new sites farther inland.
Dr. Macaulay said genetic dates had improved in recent years, now that it is affordable to decode the whole ring of mitochondrial DNA, and not just a small segment.
But he said he agreed "that archaeological dates are much firmer than the genetic ones" and that it was possible his 65,000-year date for the African exodus was too old.