Six complete mitochondrial genomes from Early Bronze Age humans in the North Caucasus

The North Caucasus region is rich in early Bronze Age sites, with burials yielding many artifacts, including those from the Chekon, Natukhaevskaya, Katusvina-Krivitsa kurgan groups (at Krasnodar Krai, Russia) and Klady kurgan (near Novosvobodnaya Village, Republic of Adygea, Russia). According to the mainstream archaeological hypothesis, these sites belong to the Maikop culture (3700-3000 years BC), with Novosvobodnaya communities representing an offshoot of Maikop ancestry. However, due to specific differences in Novosvobodnaya artifacts, the Maikop and Novosvobodnaya assemblages could represent two synchronous archaeological cultures living in almost sympatry but showing independent ancestry, from the Near East and Europe respectively. Here, we used target-enrichment together with high-throughput sequencing to characterize the complete mitochondrial sequence of three Maikop and three Novosvobodnaya individuals. We identified T2b, N1b1 and V7 haplogroups, all widely spread in Neolithic Europe. In addition, we identified the Paleolithic Eurasian U8b1a2 and M52 haplogroups, which are frequent in modern South Asia, particularly in modern India. Our data provide a deeper understanding of the diversity of Early Bronze Age North Caucasus communities and hypotheses of its origin. Analyzing non-human sequencing reads for microbial content, we found that one individual from the Klady kurgan was infected by the pathogen Brucella abortus that is responsible for zoonotic infections from cattle to humans. This finding is in agreement with Maikop/Novosvobodnaya livestock groups, mostly consisting of domestic pigs and cattle. This paper represents a first mitochondrial genome analysis of Maikop/Novosvobodnaya culture as well as the earliest brucellosis case in archaeological humans.