Palaeogenetic research at the El Sidrón Neanderthal site.

El Sidrón (Asturias, north of Spain) is a subterranean karstic system, where the remains of a contemporaneous social Neanderthal group dated to about 49,000 years ago have been being excavated since their accidental discovery in 1994. Due to the particular preservation conditions of this site, all individuals identified so far have preserved DNA, and the anticontamination measures implemented during the excavation have made palaeogenetic studies possible on all individuals. The El Sidrón samples provide unique information on the kinship relationships and on the internal genetic diversity of Neanderthal groups, thus yielding for first time empirical data for the generation of demographic models of these extinct humans. Moreover, the exceptional preservation of some bone samples has allowed the retrieval of nuclear genes associated with some phenotypic traits involved in pigmentation, blood group, language or taste perception, as well as a significant fraction (0.1%) of the nuclear genome. A future project on Neanderthal genomic diversity could be based on at least some of the El Sidrón specimens.