Abstract
Little is known about the genetic prehistory of Sardinia because of the scarcity of pre-Neolithic human remains. From a genetic perspective, modern Sardinians are known as genetic outliers in Europe, showing unusually high levels of internal diversity and a close relationship to early European Neolithic farmers. However, how far this peculiar genetic structure extends and how it originated was to date impossible to test. Here we present the first and oldest complete mitochondrial sequences from Sardinia, dated back to 10,000 yBP. These two individuals, while confirming a Mesolithic occupation of the island, belong to rare mtDNA lineages, which have never been found before in Mesolithic samples and that are currently present at low frequencies not only in Sardinia, but in the whole Europe. Preliminary Approximate Bayesian Computations, restricted by biased reference samples for Mesolithic Sardinia (the two typed samples) and Neolithic Europe (limited to central and north European sequences), suggest that the first inhabitants of the island have had a small or negligible contribution to the present-day Sardinian population, which mainly derives its genetic diversity from continental migration into the island by Neolithic times.
Highlights
Origin of modern Sardinians, and suggest that Sardinians are a “modern-day ‘snapshot’ of the genetic structure of the first farmers associated with the spread of agriculture in Europe”[31]
Genetic exchanges and replacements during the Neolithic in continental Europe have been extensively studied by means of ancient genetic data[32,33,34,35,36,37,38,39,40,41,42]; the general European picture is getting clearer, many aspects of the Neolithic transition in Sardinia are still poorly understood, starting from whether, and to what extent, gene flow from mainland Europe during the time of the spread of agriculture contributed in shaping the genetic makeup of the island
Sardinians form a distinct outlier within the genetic variation of modern Europeans[14], often interpreted as a consequence of thousands years of genetic isolation and drift, but little is known about the demographic changes that could have shaped the observed pattern of genetic variation
Summary
Origin of modern Sardinians, and suggest that Sardinians are a “modern-day ‘snapshot’ of the genetic structure of the first farmers associated with the spread of agriculture in Europe”[31] This hypothesis has not been supported so far by evidence coming from ancient Sardinian genetic data, due to the paucity of Pre-Neolithic and actual absence of EN human remains. We present the first two complete mitochondrial genome sequences of Mesolithic human remains from Sardinia, dated back to around 10,000 yBP and associated with the earliest direct evidence of human presence in the island[43] We analyzed these sequences along with modern and ancient genetic data in order to contextualize the Mesolithic Sardinian haplotypes into the European genetic variation, as well as to investigate the Paleolithic contribution to the current Sardinian gene pool. Preliminary model testing under an Approximate Bayesian Computation (ABC) framework is so far, given the extremely limited reference samples for Mesolithic Sardinia and Neolithic Europe supporting the hypothesis that modern-day Sardinian genetic variation is mostly derived from a massive migration from continental Europe during Neolithic times
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