Neanderthal genetics testing became possible in the 1990s with advances in ancient DNA analysis. In 2008, the Neanderthal genome project published the full sequence Neanderthal mitochondrial DNA (mtDNA), and in 2010 the full Neanderthal genome. Genetic data is useful in testing hypotheses about Neanderthal evolution and their divergence from early modern humans, as well as understanding Neanderthal demography, and interbreeding between archaic and modern humans.
Modern humans and Neanderthals had multiple different interbreeding episodes, but Neanderthal-derived genes in the present-day human genome descends from an episode 250,000 years ago probably in Eurasia, and 47,000 to 65,000 years ago in the Near East. While 20% of the Neanderthal genome survives today, most people only carry about a few percentage points of Neanderthal DNA, and most Neanderthal-derived DNA is non-coding. Neanderthals maintained a low genetic diversity and suffered from inbreeding depression; consequently most Neanderthal genes were probably selected out of the gene pool. Barring hybrid incompatibility or negative selection, most Neanderthal DNA may descend from the children of modern human females and Neanderthal males. Neanderthals also interbred with Denisovans in the Siberian Altai Mountains.
