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About the Authors:
Qiaomei Fu
* E-mail: [email protected]
Affiliation: Department of Evolutionary Genetics, Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany
Pavao Rudan
Affiliation: Department of Natural Sciences, Croatian Academy of Sciences and Arts, Zagreb, Croatia
Svante Pääbo
Affiliation: Department of Evolutionary Genetics, Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany
Johannes Krause
Affiliation: Institute for Archaeological Sciences, University of Tübingen, Tübingen, Germany
Introduction
Archaeological evidence suggests that agrarian societies emerged in Western Asia around 11,000 years before present (YBP) [1] and rapidly spread reaching South Eastern Europe by approximately 9,000 YBP [2]. The transition from pre-Neolithic hunter-gatherer societies to Neolithic farming and cattle breeding is often called the Neolithic revolution and marks one of the most pronounced cultural changes in European prehistory [3], [4] that can be observed in the archaeological record all over Europe [5]. By around 5,000 YBP almost all populations in mainland Europe practiced agriculture. There are two main hypotheses for how Neolithic cultures spread across Europe. The first, suggests cultural transmission as the main factor, i.e. that the new technologies and subsistence strategies were learned from neighbouring groups [6]. The second hypothesis suggests an expansion of farmer populations from the Near East into Europe, replacing most of the pre-Neolithic hunter-gatherer populations. This population replacement model, termed demic diffusion, is conceived as population spread and expansion, with limited admixture with resident populations.
Recently, mitochondrial DNA (mtDNA) from skeletal remains of European early farmers and late hunter-gatherers has been retrieved [7]–[13]. The frequency of mtDNA haplogroups, defined by substitutions shared by related mtDNA types (Phylotree.org-mtDNA tree build 12), in early farmers across Europe [7], [10]–[13] was found to be overall similar to those in modern Europeans (Figure 1, Figure S4, Figure S5), while pre-Neolithic hunter-gatherers appear to be quite distinct (Figure 1). In particular, 83% (19 out of 23) of hunter-gatherers analyzed to date carry mtDNAs belonging to haplogroup U [9], [10], [14] and none of the hunter-gatherers fall in haplogroup H. In contrast, haplogroup U has been found in only 13 of 105 (around 12%) individuals from early farming cultures of Europe and it occurs in less than 21% of modern Europeans, while haplogroup H comprises between 25% and 37% of mtDNAs retrieved from early farming cultures (Figure S4) and is...