Thursday, July 28, 2011

Modern Humans 10, Neandertals 1 - ScienceNOW

Modern Humans 10, Neandertals 1 - ScienceNOW

"This town ain't big enough for the both of us," says ranch foreman Nick Grindell to lawman Tim Barrett in the 1932 film The Western Code. Biologists know the principle well: Two animal species can rarely occupy the same niche. The same, it seems, goes for human populations. A new study of Neandertal and modern human sites in the south of France concludes that the moderns so greatly outnumbered their evolutionary cousins that Neandertals had little choice but to go extinct.

For more than 100,000 years, Neandertals had Europe all to themselves. Then, beginning roughly 40,000 years ago, modern humans—Homo sapiens—began migrating into the continent from Africa. Although researchers debate how long the Neandertals hung around, these ancient humans probably did not survive much longer than 5000 years. Just why they disappeared is also a matter of contention, but most experts agree that H. sapiens was able to outgun its rival in either direct or indirect competition for food and other resources.

Some genetic studies, based on both modern and ancient DNA sequences, have suggested that modern human population growth quickly outstripped that of Neandertals, but estimating population levels from these kinds of data is very difficult and inexact. So Paul Mellars and Jennifer French, archaeologists at the University of Cambridge in the United Kingdom, decided to look directly at the archaeological evidence for the presence of both groups in the region where the most excavations have taken place: southwestern France, including the lush Dordogne region, as well known for its prehistoric sites as for its wine and foie gras.

Mellars and French tapped into a comprehensive database of all Neandertal and H. sapiens sites in a 75,000-square-kilometer region that Pierre-Yves Demars of the University of Bordeaux had previously compiled. They looked at three prehistoric cultures and time periods: the Late Mousterian, from 55,000 to 44,000 years ago, associated with Neandertals; the Châtelperronian, from 44,000 to 40,250 years ago and also associated with Neandertals; and the Aurignacian, from 40,250 to 35,000 years ago and associated with modern humans.

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