Science unlocks Neanderthal secrets
For the first time, the genetic blueprint of an extinct human species has been
discovered. The implications, says Steve Connor, are extraordinary
Friday, 13 February 2009
Their lives may have been nasty, brutish and short but their DNA has survived
long enough to be almost fully decoded in a pioneering study that has revealed
just how closely related were the Neanderthals to modern humans.
For the first time, scientists have deciphered the genetic sequence of the
Neanderthal genome. It is the first genetic blueprint of an extinct human
species and a tour de force in terms of the scientific techniques used to
recover tiny strands of ancient DNA from fragments of fossilised bones tens of
thousand of years old.
Although scientists are far from answering the many questions about the last of
our relatives known to live alongside anatomically modern humans, they believe
that the research is close to finding out what it is, genetically, that made us
human.
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Professor Svante Paabo of the Max Planck Institute for Evolutionary
Anthropology in Leipzig will reveal at the American Association for the
Advancement of Science in Chicago this weekend that he and his colleagues have
deciphered 60 per cent of the Neanderthal genome and used it to calculate that
the last common, ape-like ancestor of modern man and the Neanderthals lived
about 830,000 years ago.
The project took more than two and half years of research on dozens of
Neanderthal bones between 40,000 and 70,000 years old and excavated from four
archaeological sites in Europe, stretching from southern Russia and Croatia, to
Germany and Spain.
They extracted enough DNA from an analysis of 70 fossilised bones to build up a
library of Neanderthal DNA covering 3.7 billion "base pairs" – the individual
letters of the genetic code – and in the process discovered that the extinct
humans were very closely related to modern people.
"The Neanderthals are so closely related to us that they fall into our
[genetic] variation," Professor Paabo said yesterday. In other words, it would
be difficult to distinguish Neanderthal DNA from the DNA of a modern European,
Asian or African.
The last Neanderthals died out about 30,000 years after sharing the same
European landscape with modern humans for many thousands of years. It has been
an enduring mystery as to why they disappeared and whether they ever interbred
with their close human cousins – although the latest evidence from the DNA
suggests they did not.
"What we have looked at from the point of view of variation today, is the
contribution from Neanderthals into the human gene pool. That was very little,
if anything. Our data shows that, if there was a contribution, it was very
small," Professor Paabo said. "But the cool thing is that interbreeding was a
two-way street. For the first time we can look at whether there was a
contribution from human ancestors into Neanderthals because, for the first
time, we have a Neanderthal genome," he said.
"We can analyse the Neanderthal genome and look at the contribution from human
ancestors into them and that question remains totally open, and the analysis is
ongoing."
Another question is whether Neanderthals could speak. Although they are known
to have a hyoid bone in the throat, which is anatomically important for
articulating words, the only other evidence comes from an analysis of a gene
called FOXP2, which is known to be critical for speech development in modern
humans. Professor Paabo said that the Neanderthal FOXP2 gene shares two changes
to its DNA sequence that is also seen in modern humans, but not in chimpanzees.
These two changes support the view that Neanderthals may have been able to
communicate verbally.
"So, from the point of view of this one gene, there is no reason to assume that
they couldn't articulate the same as we do although, of course, there are many
other genes involved in language," Professor Paabo said.
Other insights gained from a preliminary analysis of the Neanderthal genome are
that the species could not drink milk as adults – they have the same lactose
intolerance seen in the majority of modern humans – and they also have a
mutation in the gene involved in brain development seen in modern-day Africans.
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