The island of Sardinia has been of particular interest to geneticists for decades. The current model for Sardinia's genetic history describes the island as harboring a founder population that was established largely from the Neolithic peoples of southern Europe and remained isolated from later Bronze Age expansions on the mainland. To evaluate this model, we generate genome-wide ancient DNA data for 70 individuals from 21 Sardinian archaeological sites spanning the Middle Neolithic through the Medieval period. The earliest individuals show a strong affinity to western Mediterranean Neolithic populations, followed by an extended period of genetic continuity on the island through the Nuragic period (second millennium BCE). Beginning with individuals from Phoenician/Punic sites (first millennium BCE), we observe spatially-varying signals of admixture with sources principally from the eastern and northern Mediterranean. Overall, our analysis sheds light on the genetic history of Sardinia, revealing how relationships to mainland populations shifted over time.
It has been hypothesized that the Neolithic transition towards an agricultural and pastoralist economy facilitated the emergence of human adapted pathogens. Here, we recovered eight Salmonella enterica subsp. enterica genomes from human skeletons of transitional foragers, pastoralists, and agro-pastoralists in western Eurasia that were up to 6,500 years old. Despite the high genetic diversity of S. enterica all ancient bacterial genomes clustered in a single previously uncharacterized branch that contains S. enterica adapted to multiple mammalian species. All ancient bacterial genomes from prehistoric (agro-)pastoralists fall within a part of this branch that also includes the human-specific S. enterica Paratyphi C, illustrating the evolution of a human pathogen over a period of five thousand years. Bacterial genomic comparisons suggest that the earlier ancient strains were not host specific, differed in pathogenic potential, and experienced convergent pseudogenization that accompanied their downstream host adaptation. These observations support the concept that the emergence of human adapted S. enterica is linked to human cultural transformations.
Sardinians are “outliers” in the European genetic landscape and, according to paleogenomic nuclear data, the closest to early European Neolithic farmers. To learn more about their genetic ancestry, we analyzed 3,491 modern and 21 ancient mitogenomes from Sardinia. We observed that 78.4% of modern mitogenomes cluster into 89 haplogroups that most likely arose in situ. For each Sardinian-specific haplogroup (SSH), we also identified the upstream node in the phylogeny, from which non-Sardinian mitogenomes radiate. This provided minimum and maximum time estimates for the presence of each SSH on the island. In agreement with demographic evidence, almost all SSHs coalesce in the post-Nuragic, Nuragic and Neolithic-Copper Age periods. For some rare SSHs, however, we could not dismiss the possibility that they might have been on the island prior to the Neolithic, a scenario that would be in agreement with archeological evidence of a Mesolithic occupation of Sardinia.
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
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.