John, you do realise that studies of Neaderthal mitochondrial DNA have shown that they did not breed with homo-sapiens and are not part of our evolutionary history. As others have pointed out they were an evolutionary dead end, they're extinct.
Look:
[size=-1]March 28[/size][size=+1] DNA from the bones of a Neanderthal baby who died 29,000 years ago offers further evidence that Neanderthals are cousins rather than ancestors of modern humans.[/size]
Writing in Thursdays issue of the journal
Nature, William Goodwin of the University of Glasgow in Scotland, along with collaborators from Russia and Sweden, report that the babys DNA is much more similar to another Neanderthal DNA sequence reported in 1997 than to that of modern humans.
[size=+1]Evolution or Replacement?[/size]
Some anthropologists have argued that people evolved at least partly from the Neanderthals. The opposing theory is that modern humans evolved in Africa, then spread outward, overwhelming earlier hominids including Neanderthals. The short, squat Neanderthals inhabited much of Europe from about 100,000 years ago until dying out about 28,000 years ago.
"Neanderthal DNA is distinct from modern humans," Goodwin says, "and there are no examples of humans having Neanderthal-type DNA."
[size=-2]The shaded area indicates the known range of Neanderthals. Mezmaiskaya is the location where the baby Neanderthal whose DNA was sequenced was found. An earlier Neanderthal DNA sequence was determined from bones found in Feldhofer Cave in Germany.[/size]
[size=-2](ABCNEWS.com/ Magellan Geographix)[/size]
The researchers isolated segments of DNA from the babys mitochondria small, energy-producing bodies within a cell that contain their own genetic code separate the main DNA strand in the nucleus of the cell. Mitochondrial DNA is easier to study, because each cell contains about 1,000 mitochondria, meaning there are about 1,000 times more DNA strands to extract. Unlike cell DNA, mitochondrial DNA is inherited only from the mother.
[size=+1]Not Human Enough[/size]
The babys mitochondrial DNA differed from that of the other Neanderthal in 3.5 percent of the locations tested, while the divergence from humans was 7 percent. Scientists consider that to be a substantial gap. "It all points away from the Neanderthal," Goodwin says.
Based on the number of differences, and the expected rate of change, Neanderthals and humans last shared a common ancestor about 500,000 years ago, the researchers say.
The Neanderthal DNA was also no more similar to the DNA of Europeans than people elsewhere, which might have been expected if Neanderthals had mated in large numbers with their human neighbors in Europe.
The baby, found in Russias Caucasus Mountains, has been estimated in age at somewhere between an unborn 7-month-old fetus and a newborn of a couple of months. Molecular biologist Matthias Hoss, an expert in ancient remains now working at the Swiss Institute for Cancer Research, said the research appears to support the theory that Neanderthals were an evolutionary dead end.
"This adds quite a lot of confidence that the Neanderthal didnt contribute to modern populations," he said.