Our ancestors are now thought to have mated with at least two kinds
of archaic humans at two different times and places.
Pääbo suggests that X Woman may belong to a group
of archaic humans who migrated out of Africa at a different time from Neanderthals or modern humans.
«It is very satisfying to see that gene flow from Denisovans, an extinct
group of archaic humans that we discovered only four years ago, is now found to have had important consequences for people living today,» says Pääbo.
She also existed thousands of years after Neanderthals died out, and the paleoanthropologists who found her think she's from a different
species of archaic humans.
«Our work demonstrates that the generation of genome sequences from a large
number of archaic human individuals is now technically feasible, and opens the possibility to study Neandertal populations across their temporal and geographical range,» says Janet Kelso, the senior author of the new study.
To do the work — the most complete
reconstruction of archaic human DNA to date — Matthias Meyer at the Max Planck Institute for Evolutionary Anthropology in Germany amplified wisps of DNA from an 80,000 - year - old fingertip bone, yielding sequences as detailed as those swabbed from someone's cheek today.
What is known about Denisovan ancestry comes from a single
set of archaic human fossils found in the Altai mountains in Siberia.
Fossil fragments (yellow) were put together with their mirror - image pieces (purple) to visualize the
skull of an archaic human who lived in eastern China.
Modern humans co-existed and interbred not only with Neanderthals, but also with another
species of archaic humans, the mysterious Denisovans.
Both of these archaic human cousins lived in the same cave, although at different times in the past.