Population history from the Neolithic to present on the Mediterranean island of Sardinia: An ancient DNA perspective

Abstract

34Recent ancient DNA studies of western Eurasia have revealed a dynamic history of admixture, 35 with evidence for major migrations during the Neolithic and Bronze Age. The population of the 36 Mediterranean island of Sardinia has been notable in these studies -Neolithic individuals from 37 mainland Europe cluster more closely with Sardinian individuals than with all other present-day 38 Europeans. The current model to explain this result is that Sardinia received an initial influx 39 of Neolithic ancestry and then remained relatively isolated from expansions in the later Ne-40 olithic and Bronze Age that took place in continental Europe. To test this model, we generated 41 genome-wide capture data (approximately 1.2 million variants) for 43 ancient Sardinian individu-42 als spanning the Neolithic through the Bronze Age, including individuals from Sardinia's Nuragic 43 culture, which is known for the construction of numerous large stone towers throughout the is-44 land. We analyze these new samples in the context of previously generated genome-wide ancient 45 DNA data from 972 ancient individuals across western Eurasia and whole-genome sequence data 46 from approximately 1,500 modern individuals from Sardinia. The ancient Sardinian individuals 47 show a strong affinity to western Mediterranean Neolithic populations and we infer a high degree 48of genetic continuity on the island from the Neolithic (around fifth millennium BCE) through 49 the Nuragic period (second millennium BCE). In particular, during the Bronze Age in Sardinia, 50 we do not find significant levels of the "Steppe" ancestry that was spreading in many other parts 51 of Europe at that time. We also characterize subsequent genetic influx between the Nuragic 52 period and the present. We detect novel, modest signals of admixture between 1,000 BCE and 53 present-day, from ancestry sources in the eastern and northern Mediterranean. Within Sardinia, 54 we confirm that populations from the more geographically isolated mountainous provinces have 55 experienced elevated levels of genetic drift and that northern and southwestern regions of the 56 island received more gene flow from outside Sardinia. Overall, our genetic analysis sheds new 57 light on the origin of Neolithic settlement on Sardinia, reinforces models of genetic continuity on 58 the island, and provides enhanced power to detect post-Bronze-Age gene flow. Together, these 59 findings offer a refined demographic model for future medical genetic studies in Sardinia.60

The spread of steppe and Iranian-related ancestry in the islands of the western Mediterranean

“…An ancient DNA study of Sardinia that appears alongside this one concurs that modern Sardinians harbor large proportions of ancestry from early Sardinian farmers as well as significant contributions from later periods that are larger than previously estimated. That second study also agrees with our finding that many coastal Sardinian sites harbored people with little ancestry from earlier local Sardinians in the Iron Age and antiquity 85 .…”

Ancient genomes reveal social and genetic structure of Late Neolithic Switzerland

“…Therefore, it cannot be excluded, that these females also originate from regions further south since also some regions e.g., Italy are not genetically described so far for this particular time span. However, individuals without any steppe-related ancestry can be found up until 2479-1945 BCE for example in Iberia or until 2900-1700 BCE in the Minoan population of Crete 21,36 and even later on Sardinia where steppe-related ancestry arrives around 300 CE 37 and where studies of present-day Sardinians found indications of continuity in mountainous regions since Neolithic times 38 .…”

“…Then the membrane was washed two times with 720 μl of the commercial PE buffer form Qiagen, and then the DNA was eluted in 100 μl TET buffer (1 mM EDTA, 10 mM Tris-HCl, 0.05 % Tween-20, ref. 38 ). Sequencing libraries were prepared after 39 .…”

Y-chromosome and Surname Analyses for Reconstructing Past Population Structures: The Sardinian Population as a Test Case

“…The recent and detailed reconstruction of the phylogeny of this haplogroup [56] has revealed that the rare European R1b-V88 lineages (R1b-M18 and R1b-V35) originated from the root of the phylogeny much earlier (about 12.34 kya) than the separation of the African lineages (7.85 ± 0.90 kya), thus supporting an origin of R1b-V88 outside Africa and a subsequent diffusion in sub-Saharan Africa through the Last Green Sahara period during the Middle-Holocene [56]. Interestingly, recent studies on ancient DNA [60,61,62] identified the most ancient R1b-V88 samples (dated 11 and 9 ky) in East Europe (Serbia and Ukraine, respectively) and more recent R1b-V88 samples (dated 7 and 6 ky) in Spain (I0410) and Germany (I1593, I0559) thus supporting a European origin and opening new grounds for discussion concerning the routes towards Africa and Sardinia, where R1b-V88 characterizes a considerable number of ancient specimens [62,63].…”