ИСТИНА

The Caucasus mountains, bound by the Black and Caspian seas, connect the Near East and the Eurasian steppes. Recent archaeogenetics studies have described the formation of 'steppe ancestry' ultimately as a mixture of Eastern European and Caucasian huntergatherers. However, it remains unclear when this ancestry arose and whether cultural innovations originating in the Near East had facilitated the opening of the steppe environment for pastoralist economies. To test whether this also involved gene flow, we generated genome-wide SNP data from 50 prehistoric individuals along a 3000-year transect through time in the North Caucasus region, ranging from the Eneolithic (6300 yBP) to the Late Bronze Age (3400 yBP). We observe a genetic separation between the groups in the northern foothills and south of the Caucasus, and those of the bordering steppe regions in the north. We coin these 'mountain' and 'steppe' Caucasus groups, according to vegetation zones and characteristics of the associated archaeological cultures. Furthermore, 'Steppe Majkop' individuals harbor a distinct ancestry component that relates them to Upper Paleolithic Siberians and Native Americans. In contrast, genomic ancestry profiles of groups from the northern foothills are similar to those in ancient Georgia and Armenia. This suggests that the Caucasus Mountains are not an insurmountable barrier to human movement, and further permits the detection of periods of genetic continuity as well as occasional gene flow. Intriguingly, individuals associated with Yamnaya and subsequent pastoralist cultures show subtle evidence for Anatolian Neolithic-farming-related ancestry, possibly from different sources in the western and southern contact zones.