Figure 2. The three Eneolithic clines in the context of Eneolithic and Bronze Age admixture.

Six 3-source models elucidate a complex history of admixture. Individuals plotted at the triangle edge fit (p>0.05); the simpler 2-source model is plotted for individuals with a negative coefficient from one of the three sources. The corners of each triangle represent the sources. Unplotted individual all give fits at P<0.05 and so should be viewed as poorly described by the model. (a) Caucasus and European hunter-gatherer admixtures in the “Old Steppe”: Krivyansky on the Lower Don received much more CHG-related admixture than upriver people of the Middle Don at Golubaya Krinitsa. In the Middle and Upper Volga and the Kama River, populations belonged to the old EHG cline with negligible CHG-related influence. (b) The “Don-Volga” difference. On the Lower Volga and North Caucasus piedmont, the BPgroup did receive CHG-related ancestry like its western Lower Don counterpart at Krivyansky; but, unlike Krivyansky, it also received ancestry from Central Asia; this eastern influence was higher still in the Bronze Age Steppe Maikop. (c) The “Volga Cline” vis-à-vis the Don: populations at Khvalynsk, Klopkov Bugor, and Ekaterinovka are clinal between the Berezhnvoka cluster on the Lower Volga and the upriver EHG-like populations of the Middle Volga (Labazy and Lebyazhinka). (d) the “Volga Cline” vis-à-vis Central Asia: a slight excess of Central Asian ancestry in the Khi subset of Khvalynsk. (e) the “Dnipro” cline: the Core Yamnaya are on one end of a cline that also includes the Don Yamnaya and Serednii Stih populations. The cline is formed by admixture from the “Caucasus-Lower Volga” (CLV) cline that is formed by differential admixture of Neolithic Caucasus and BPgroup people. The CLV Cline includes diverse people buried in kurgans at Berezhnovka, Progress-2, Remontnoye, and Maikop sites Klady and Dlinnaya-Polyana ~5000–3000 BCE. (f) “West Asian”: CLV ancestry first appears in the Chalcolithic population at Areni-1 in Armenia and is also present in the Bronze Age at Maikop. The majority of the ancestry in both populations is from West Asian sources from the Mesopotamia-Caucasus (or Çayönü-Masis Blur-Aknashen) cline. Chalcolithic and Bronze Age Anatolians lack CLV ancestry but traces of it can be found in Bronze Age Central Anatolians.