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Neolithic and Bronze Age migration to Ireland

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Republication from pnas.org

Significance

Modern Europe has been shaped by two episodes in prehistory, the advent of agriculture and later metallurgy. These innovations brought not only massive cultural change but also, in certain parts of the continent, a change in genetic structure. The manner in which these transitions affected the islands of Ireland and Britain on the northwestern edge of the continent remains the subject of debate. The first ancient whole genomes from Ireland, including two at high coverage, demonstrate that large-scale genetic shifts accompanied both transitions. We also observe a strong signal of continuity between modern day Irish populations and the Bronze Age individuals, one of whom is a carrier for the C282Y hemochromatosis mutation, which has its highest frequencies in Ireland today.

Abstract

The Neolithic and Bronze Age transitions were profound cultural shifts catalyzed in parts of Europe by migrations, first of early farmers from the Near East and then Bronze Age herders from the Pontic Steppe. However, a decades-long, unresolved controversy is whether population change or cultural adoption occurred at the Atlantic edge, within the British Isles. We address this issue by using the first whole genome data from prehistoric Irish individuals.

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India: Five distinct ancestral components and a complex structure revealed by genomic reconstruction of the history of extant populations

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Republication from pnas.org

(A) Scatterplot of 331 individuals from 18 mainland Indian populations by the first two PCs extracted from genome-wide genotype data. Four distinct clines and clusters were noted; these are encircled using four colors. (B) Estimates of ancestral components of 331 individuals from 18 mainland Indian populations. A model with four ancestral
 components (K = 4) was the most parsimonious to explain the variation and similarities of the genomewide genotype data on the 331 individuals. Each individual is represented by a vertical line partitioned into colored segments whose lengths are proportional to the contributions of the ancestral components to the genome of the individual. Population
labels were added only after each individual’s  ancestry had been estimated. We have used green and red to represent ANI and ASI ancestries; and cyan and blue with the inferred AAA and ATB ancestries. These colors correspond to the colors  used to encircle clusters of individuals in A. (Also see  SI Appendix, Figs. S2 and S3.)

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Significance

India, harboring more than one-sixth of the world population, has been underrepresented in genome-wide studies of variation. Our analysis reveals that there are four dominant ancestries in mainland populations of India, contrary to two ancestries inferred earlier. We also show that (i) there is a distinctive ancestry of the Andaman and Nicobar Islands populations that is likely ancestral also to Oceanic populations, and (ii) the extant mainland populations admixed widely irrespective of ancestry, which was rapidly replaced by endogamy, particularly among Indo-European–speaking upper castes, about 70 generations ago. This coincides with the historical period of formulation and adoption of some relevant sociocultural norms.

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P. Mitochondrial Genomes Suggest a Single Major Dispersal of Non-Africans and a Late Glacial Population Turnover in Europe

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Republished from Cell.com

 

Late Pleistocene and Early Holocene Archeological Sites and Hunter-Gatherer mtDNA Haplogroups

(A) Pre-LGM dispersal of non-African populations, carrying both M and N lineages (hgs R, U, U5, and U2′3′4′7′8′9 belong to the N clade, distinct from the M clade).

(B) Post-LGM re-expansion in Europe while ice sheets retracted.

(C) Late Glacial shift in mtDNA hg frequency.

(D) Holocene hunter-gatherer mtDNA, mainly belonging to hg U5.

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How modern humans dispersed into Eurasia and Australasia, including the number of separate expansions and their timings, is highly debated [1, 2]. Two categories of models are proposed for the dispersal of non-Africans: (1) single dispersal, i.e., a single major diffusion of modern humans across Eurasia and Australasia [3, 4, 5]; and (2) multiple dispersal, i.e., additional earlier population expansions that may have contributed to the genetic diversity of some present-day humans outside of Africa [6, 7, 8, 9]. Many variants of these models focus largely on Asia and Australasia, neglecting human dispersal into Europe, thus explaining only a subset of the entire colonization process outside of Africa [3, 4, 5, 8, 9].

 

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Rethinking the dispersal of Homo sapiens out of Africa

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Republication from Wiley Online library

Current fossil, genetic, and archeological data indicate that Homo sapiens originated in Africa in the late Middle Pleistocene. By the end of the Late Pleistocene, our species was distributed across every continent except Antarctica, setting the foundations for the subsequent demographic and cultural changes of the Holocene. The intervening processes remain intensely debated and a key theme in hominin evolutionary studies. We review archeological, fossil, environmental, and genetic data to evaluate the current state of knowledge on the dispersal of Homo sapiens out of Africa.

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Recent Admixture in Forming the Contemporary West Eurasians

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Republication from cell.com

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Highlights

  • Recent admixture events involved outside groups at the edges of West Eurasia
  • Admixture within Europe tended to fall within the European Migration Period
  • West Eurasian genetic structure today is likely to have been maintained by admixture

Summary

Over the past few years, studies of DNA isolated from human fossils and archaeological remains have generated considerable novel insight into the history of our species. Several landmark papers have described the genomes of ancient humans across West Eurasia, demonstrating the presence of large-scale, dynamic population movements over the last 10,000 years, such that ancestry across present-day populations is likely to be a mixture of several ancient groups [ 1–7 ].

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Extensive West Eurasian admixture throughout the African continent revealed

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Reoublication from Science mag

Characterizing genetic diversity in Africa is a crucial step for most analyses reconstructing the evolutionary history of anatomically modern humans. However, historic migrations from Eurasia into Africa have affected many contemporary populations, confounding inferences. Here, we present a 12.5x coverage ancient genome of an Ethiopian male (‘Mota’) who lived approximately 4,500 years ago. We use this genome to demonstrate that the Eurasian backflow into Africa came from a population closely related to Early Neolithic farmers, who had colonized Europe 4,000 years earlier.

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