A new study concludes that humans mated with Neanderthals 50,000
to 80,000 years ago, leaving traces of the Neanderthal genome in
some modern humans.
We have met Neanderthals, and they are us - or about 1 to 4
percent of each of us.
That is one implication of a four-year effort to sequence the
Neanderthal genome - essentially setting out in order some 3 billion
combinations of four key molecules that together represent the
Neanderthals' genetic blueprint.
So far, the international team reporting the results notes that
they've sequenced 60 percent of the Neanderthal genome. And the 60
percent they have - essentially a rough draft - is likely to be rife
with errors that will emerge and get corrected over time.
Still, the results mark "just the beginning of an exploration of
human uniqueness that it now possible" as anthropologists move
beyond fossils to genes in uncovering the story of human evolution,
says Svante Paabo, who heads the Neanderthal Genome Project at the
Max Planck Institute for Evolutionary Anthropology in Leipzig,
Among the tale the genes tell: A few anatomically modern humans
mated with Neanderthals, likely in North Africa or the Middle East
as modern humans initially were moving out of Africa, the
The team came to that conclusion after comparing the Neanderthal
genome with those of five humans today: one each from Europe, Asia,
and Papua New Guinea, and two from different regions of sub-Saharan
Africa. They found that from 1 to 4 percent of the DNA in the
genomes of people from Eurasia and the southwestern Pacific were
inherited from Neanderthals. Neanderthal-derived genes failed to
show up in the African genomes.
The results overturn what Dr. Paabo calls the "hard out-of-
Africa hypothesis" in which a small group of anatomically modern
humans migrates from Africa "and replaced everyone else in the world
without any admixture." It's entirely possible that African genomes
also contain some other form of what Paabo dubs "caveman biology"
from more archaic hominins. "We just don't know that yet," he says.
Nor is it clear yet whether the presence of this DNA in modern
humans represents positive selection - genetic material worth
holding on to - or biological antiques whose functions have long
been lost, the researchers say. So far, the inherited material does
not seem to be concentrated in genes, but spread somewhat randomly
in non-gene portions of the modern-human genomes. …