Michael Eisenstein in Nature:
Some 60,000 years ago, Neanderthals in western Eurasia acquired strange new neighbours: a wave of Homo sapiens migrants making their way out of Africa, en route to future global dominance. Now, a study1 of hundreds of ancient and modern genomes has pinpointed when the two species began pairing off — and has found that the genetic intermingling lasted for only a short time, at least on an evolutionary scale.
The high-resolution analysis also allowed the authors to track when certain Neanderthal DNA sequences appeared in the H. sapiens genome and determine whether they were retained.
More here.