A Breed Apart
DNA Tests: Humans Not Descended from Neanderthals
By Kenneth Chang
March 28 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.
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.
Evolution or Replacement?
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.
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. (ABCNEWS.com/
The researchers isolated segments of DNA from the babys mitochondria small,
energy-producing bodies that contain their own genetic code separate from 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.
Not Human Enough
The babys mitochondrial DNA differed from that of the other Neanderthal in 3.5
percent of the locations tested, while the divergence of the Neanderthal DNA from humans
was twice as great: 7 percent. Scientists consider that to be a substantial gap.
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.
Loring Brace, an anthropologist at University of Michigan and a proponent of the idea that
people descended from Neanderthals he argues that features of skulls show a steady
progression from Neanderthal to human says the DNA evidence does not sway him.
Different patterns of movement may have caused mitochrondial DNA to diverge more quickly
in the past, he says. The whole picture is still very spotty, Brace says.
Erik Trinkaus, an anthropologist at Washington University in St. Louis, says the DNA
evidence does not disprove his assertion that the 25,000-year-old skeleton of a child
unearthed in Portugal is the descendent of a human-Neanderthal hybrid. The new research,
he says, just shows interbreeding was not common.
There is no contradiction, he says.
Goodwin also says his finding isnt the final word. Perhaps Neanderthals and humans
mated and produced sterile offspring, similar to mules, the crossbreed of horses and
donkeys. Its very hard to prove any negative, Goodwin says. I
wouldnt claim this to be conclusive.
The Associated Press contributed to this report.