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Old August 6th, 2013 #5
Jean West
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The potential for conflict (shades of Kennewick Man?) here involves the Out of Africa vs. Multi-regional hypotheses (see bottom of page for definitions).

Blow to Neanderthal breeding theory
13 May, 2003



Early modern humans and Neanderthals probably did not interbreed, according to evidence collected by Italian scientists.

Neanderthal man Interbreeding debate continues

Researchers have long considered Neanderthals and the humans that lived in Europe 30,000 years ago as distinct species, even though they lived side by side. However, there is controversy over theories that Neanderthals made a contribution to the gene pool of people living today. This has been fuelled by a skeleton uncovered in Portugal that appears to show both Neanderthal and human features.

DNA taken

The latest research, from the University of Ferrara in Italy, compared genetic material from Neanderthals, Cro-Magnon humans and 21st-Century Europeans.

The DNA from the Neanderthals and Cro-Magnons was taken from their bones.

The genetic material was extracted from cell structures called mitochondria rather than the nucleus.

The scientists found that while, unsurprisingly, modern humans show clear genetic signs of their Cro-Magnon ancestry, no such link between Neanderthal DNA and modern European DNA could be established.

The results, they say, indicate that Neanderthals made little or no contribution to the genes of modern humans.

Out of Africa

The mitochondrial DNA of the two ancient species was very different, claims the study. "This discontinuity is difficult to reconcile with the hypothesis that both Neanderthals and early anatomically modern humans contributed to the current European gene pool."

The findings are said to support the theory that the "anatomically modern human" arose in Africa some 150,000 years ago and then dispersed across the globe, displacing the Neanderthals on the way.

It is a blow to the so-called multi-regional theory, in which some interbreeding between Neanderthal and early humans is said to have taken place.

The latest study is reported in the journal Proceedings of the National Academy of Sciences (PNAS).
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Out-of-Africa versus the multiregional hypothesis

Broadly speaking, there are two competing hypotheses on the origin of modern humans: the Out-of-Africa hypothesis and the multiregional hypothesis. Both agree that Homo erectus originated in Africa and expanded to Eurasia about one million years ago, but they differ in explaining the origin of modern humans (Homo sapiens sapiens). The first hypothesis proposes that a second migration out of Africa happened about 100,000 years ago, in which anatomically modern humans of African origin conquered the world by completely replacing archaic human populations (Homo sapiens; Model A). The multiregional hypothesis states that independent multiple origins (Model D) or shared multiregional evolution with continuous gene flow between continental populations (Model C) occurred in the million years since Homo erectus came out of Africa (the trellis theory). A compromised version of the Out-of-Africa hypothesis emphasizes the African origin of most human populations but allows for the possibility of minor local contributions (Model B).

© 2000 Nature Publishing Group Jin, L. & Su, B. Natives or immigrants: modern human origin in east Asia. Nature Reviews Genetics 1, 127.

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