R1b already present in Romania since the Mesolithic era.

**Voskos** · 06-19-2017, 08:28 AM

The transition from hunting and gathering to farming involved profound cultural and technological changes. In Western and Central Europe, these changes occurred rapidly and synchronously after the arrival of early farmers of Anatolian origin [1, 2, 3], who largely replaced the local Mesolithic hunter-gatherers [1, 4, 5, 6]. Further east, in the Baltic region, the transition was gradual, with little or no genetic input from incoming farmers [7]. Here we use ancient DNA to investigate the relationship between hunter-gatherers and farmers in the Lower Danube basin, a geographically intermediate area that is characterized by a rapid Neolithic transition but also by the presence of archaeological evidence that points to cultural exchange, and thus possible admixture, between hunter-gatherers and farmers. We recovered four human paleogenomes (1.1× to 4.1× coverage) from Romania spanning a time transect between 8.8 thousand years ago (kya) and 5.4 kya and supplemented them with two Mesolithic genomes (1.7× and 5.3×) from Spain to provide further context on the genetic background of Mesolithic Europe. Our results show major Western hunter-gatherer (WHG) ancestry in a Romanian Eneolithic sample with a minor, but sizeable, contribution from Anatolian farmers, suggesting multiple admixture events between hunter-gatherers and farmers. Dietary stable-isotope analysis of this sample suggests a mixed terrestrial/aquatic diet. Our results provide support for complex interactions among hunter-gatherers and farmers in the Danube basin, demonstrating that in some regions, demic and cultural diffusion were not mutually exclusive, but merely the ends of a continuum for the process of Neolithization.
Results

We investigated the interactions between hunter-gatherers and Neolithic farmers in the Lower Danube basin in Romania by recovering the genomes of four prehistoric individuals: a Mesolithic hunter-gatherer from Ostrovul Corbului (OC1_Meso) dated at 8.7 thousand years ago (kya), two Mesolithic hunter-gatherers from Schela Cladovei (SC1_Meso and SC2_Meso) dated at around 8.8 kya, and an Eneolithic (the period between the Neolithic and the Bronze Age) individual dated at 5.3 kya from Gura Baciului (GB1_Eneo), located north-northeast of the Iron Gates on a terrace of the Suceag creek (Figure 1A and STAR Methods, Method Details). Contact between hunter-gatherers and farmers has been hypothesized for a number of archaeological sites across Europe. In 2012, Skoglund et al. [4] reported the first genomic data suggesting different origins for hunter-gatherers and early farmers in Scandinavia. Further work [1, 5, 6] provided additional paleogenomic evidence that Neolithization was driven by immigration of farming populations, supporting the demic diffusion model, at least for Scandinavia and Western and Central Europe. In Southeast Europe, the Lower Danube Basin has provided some of the best evidence for cultural exchange, and thus possible mixing, between hunter-gatherers and farmers [10, 11, 12]. Archaeological data put the arrival of the typical Neolithic package, including farming, pottery, and new burial practices, at around 8 kya. Isotopic analysis of very late Mesolithic burials from Lepenski Vir around that time revealed several individuals whose diets were relatively high in terrestrial proteins, a profile more typical of farming communities [11]; although the genetic origin of these individuals is unknown, their presence points to contact of this Mesolithic community with farmers (either through cultural exchange or immigration). The presence of personal ornaments of Neolithic type in some Late Mesolithic (8.3–8.0 kya) graves at Lepenski Vir and Vlasac [13] and the recovery of cereal starch granules from dental calculus on Mesolithic teeth from Vlasac [12] further support the hypothesized adoption of new practices by local hunter-gatherers in the Lower Danube basin

We investigated a number of phenotypic traits in our ancient samples. All three Romanian Mesolithic individuals were predicted to have dark hair and brown eyes, whereas the Eneolithic individual was predicted to have dark hair and light eye pigmentation (Figure S2 and Table S3). Based on the presence of the ancestral forms of both SLC45A2 (rs1426654) and SLC24A5 (rs16891982), two genes that were found to have gone through strong positive selection for skin depigmentation in the ancestors of modern Europeans, the three Romanian Mesolithic individuals were predicted to have had dark skin pigmentation. The Eneolithic individual most likely had a lighter skin tone, as it was homozygous for the derived version of SLC45A2 and heterozygous for the derived version of SLC24A5. Although an increase in the frequencies of these variants is generally associated with the Neolithic, it should be noted that they were already present at low frequency among Scandinavian hunter-gatherers [8], and a copy of the derived variant of SLC45A2 was also present in our late Spanish Mesolithic sample, Canes1_Meso. All individuals investigated were unlikely to be able to digest lactose as adults, as they all carried ancestral alleles at two key positions in the gene MCM6 (rs4988235 and rs182549).

Y and mt DNA:

At the level of mitochondrial DNA sequences, SC1_Meso belongs to U5b (Table 1), the same subhaplogroup to which a number of Western hunter-gatherers (WHGs) belong [17, 18, 19, 20]. SC2_Meso was assigned to U5a, a subhaplogroup mainly found in Scandinavian [5, 21] and Latvian hunter-gatherers and also in some samples from later periods in Eastern and Central Europe [6, 7, 22]. The two other samples from Romania, the Mesolithic OC1_Meso and the Eneolithic GB1_Eneo, both belong to K1, a haplogroup commonly found among early European farmers [17, 18] (see Table S4 and Method Details in STAR Methods for description of haplogroup assignment). At the Y chromosome level, all of our three male samples, SC1_Meso, SC2_Meso, and OC1_Meso, were assigned to the R1 and R1b haplogroups, both common in modern Europeans

Source: http://dx.doi.org/10.1016/j.cub.2017.05.023