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Neanderthals not human ancestors
BBC (08-09-05)

Modern humans do not have Neanderthal ancestors in their family tree, a new DNA study concludes. The DNA extracted from the ribs of a Neanderthal infant buried in southern Russia 29,000 years ago was found to be too distinct from modern human DNA to be related.

"There wasn't much, if any mixture, between Neanderthals and modern humans," said William Goodwin, of the University of Glasgow, UK. "Though they co-existed, we can't find any evidence of genetic material being passed from Neanderthals to modern humans."

The new work, published in the journal Nature, contradicts recent evidence from ancient remains of a child found in Portugal, which appeared to combine Neanderthal and human features. Those researchers concluded that some interbreeding must have taken place.

Last of the Neanderthals

The bones from the Neanderthal infant were very well preserved and the child must have been among the last of the Neanderthals as they died out about 30,000 years ago.

Exactly what happened to them is a mystery. Conflicting theories suggest that they were massacred, out-competed for food or simply absorbed by interbreeding with modern humans.

The research by Dr Goodwin and his Swedish and Russian colleagues agrees with the findings of the first analysis of Neanderthal DNA in 1997.

That study of DNA, taken from the first Neanderthal skeleton found in the Feldhofer Cave in Germany in 1856, supports the theory that modern humans replaced Neanderthals.























Neanderthal-to-Human Link Severed

Researchers conducted the first studies on three distinct Neandhertal specimens that date between 30,000 and possibly 100,000 years in age, from three locations in the Neanderthal’s range (Germa- ny, Russia, and Croatia). The DNA sequences obtained for all three Neanderthal specimens display remarkable agreement with one another. In fact, the DNA sequences vary by only about 3.7%. This sequence diversity compares favorably to that measured for modern humans (3.4%). Such similarity within the species, but dissimilarity between the species, indicates that these animals did not make any genetic (hence, evolutionary) contribution to modern humans.

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Little diversity
According to Dr Goodwin, the DNA sequence from the infant was very similar to the specimen from the Feldhofer Cave, proving that there was little diversity among Neanderthals.

"If they had been very diverse at the DNA level, they could have encompassed modern humans. The fact that these two Neanderthals are closely related and not related to modern humans implies that they don't have the diversity to encompass a modern human gene pool," said Dr Goodwin.

DNA comparisons also showed that different ethnic groups do not have any links to Neanderthals. In a commentary on the research in Nature, Matthias Hoss, of the Swiss Institute for Experimental Cancer Research, said the two studies provide the most reliable proof so far of the authenticity of ancient DNA sequences.

The similar features of the two samples "argues against the idea that modern Europeans are at least partly of Neanderthal origin," he said.

BBC

More recently, scientists have isolated, amplified, and sequenced mitochondrial DNA for two more Neanderthal specimens. The specimens were recovered from new excavations of Feldhofer cave deposits—the location in the Neander Valley, Germany, where Neanderthal remains were first discovered.2 The DNA sequences of these two newly discovered specimens closely agree with those obtained for the three earlier studies and fall within the parameters for Neanderthal genetic diversity.

Ancient-DNA analysis makes many scientists uneasy, since contamination can readily creep in during the isolation and amplification processes. This wariness, however, can be confidently dispelled for the Neanderthal mitochondrial DNA sequences since independent research teams have generated consistent results for five different specimens. The conclusion is undeniable: Neanderthals did not give rise to modern humans.

References:

  1. Matthias Krings et al., "Neanderthal DNA Sequences and the Origin of Modern Humans," Cell 90 (1997): 19-30; Matthias Krings et al., "DNA Sequence of the Mitochondrial Hypervariable Region II from the Neanderthal Type Specimen," Proceedings of the National Academy of Sciences, USA 96 (1999): 5581-85; Igor V. Ovchinnikov et al., "Molecular Analysis of Neanderthal DNA from the Northern Caucasus," Nature 404 (2000): 490-93; Matthias Krings et al., "A View of Neanderthal Genetic Diversity," Nature Genetics 26 (2000): 144-46.
  2. Ralf W. Schmitz et al., "The Neanderthal Type Site Revisited: Interdisciplinary Investigations of Skeletal Remains from the Neander Valley, Germany," Proceedings of the National Academy of Sciences, USA 99 (2002): 13342-47.