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Recent African origin of modern humans

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In paleoanthropology, the single origin hypothesis (or Out-of-Africa model) is one of two competing accounts of the origin of anatomically modern humans, Homo sapiens sapiens.

Scientists do not dispute that the first species of the genus Homo, Homo habilis, evolved in Africa around two million years ago, and that members of this genus migrated "out of Africa" somewhat later. Their descendants have become known through fossils discovered far from Africa, such as "Peking man" and "Java man." The Neanderthals are also considered to have descended from early migrants.

According to the single-origin model, however, every species of the genus Homo was driven extinct but one: Homo sapiens (anatomically modern humans). This species evolved in Africa between 100,000 and 200,000 years ago, and began colonizing the rest of the world some time afterwards. According to the single-origin model, these migrants did not interbreed with the scattered descendants of earlier exoduses; for this reason, the model is sometimes called the "replacement scenario." In support of it, advocates have drawn from both fossil and DNA evidence, in particular from mitochondrial and Y-chromosome DNA sequences.

The opponents of a single origin argue that interbreeding indeed did occur, and that the characteristics of modern humans, including those that distinguish the races, reflect genetic contributions from several lineages that evolved semi-independently in different parts of the world. This is the "multiregional model".

Proponents

Literature

  • Stringer, Chris and Robin McKie, African Exodus, ISBN 0-7126-7307-5 (paperback), 1996.
  • Cavalli-Sforza, Luigi Luca and Francesco Cavalli-Sforza, The Great Human Diasporas - The History of Diversity and Evolution (Italian original Chi Siamo: La Storia della Diversit`a Umana), ISBN 0-201-44231-0 (paperback), 1993.
  • Foley, Robert, Humans Before Humanity, ISBN 0-631-20528-4 (paperback), 1995.

External References

"Modern Men Trace Ancestry to African Migrants," Science magazine, 2001 [1]

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