Author
Aleksandr Khokhlov
Bio: Aleksandr Khokhlov is an academic researcher from Samara State University. The author has contributed to research in topics: Population & Geography. The author has an hindex of 6, co-authored 8 publications receiving 2123 citations.
Topics: Population, Geography, Archaeology, Steppe, Chalcolithic
Papers
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University of Adelaide1, Harvard University2, Broad Institute3, Howard Hughes Medical Institute4, University of Mainz5, Max Planck Society6, University of Tübingen7, Hungarian Academy of Sciences8, Stockholm University9, Facultad de Filosofía y Letras10, The Heritage Foundation11, University of Basel12, Autonomous University of Barcelona13, University of Valladolid14, Hartwick College15
TL;DR: In this paper, the authors generated genome-wide data from 69 Europeans who lived between 8,000-3,000 years ago by enriching ancient DNA libraries for a target set of almost 400,000 polymorphisms.
Abstract: We generated genome-wide data from 69 Europeans who lived between 8,000-3,000 years ago by enriching ancient DNA libraries for a target set of almost 400,000 polymorphisms. Enrichment of these positions decreases the sequencing required for genome-wide ancient DNA analysis by a median of around 250-fold, allowing us to study an order of magnitude more individuals than previous studies and to obtain new insights about the past. We show that the populations of Western and Far Eastern Europe followed opposite trajectories between 8,000-5,000 years ago. At the beginning of the Neolithic period in Europe, ∼8,000-7,000 years ago, closely related groups of early farmers appeared in Germany, Hungary and Spain, different from indigenous hunter-gatherers, whereas Russia was inhabited by a distinctive population of hunter-gatherers with high affinity to a ∼24,000-year-old Siberian. By ∼6,000-5,000 years ago, farmers throughout much of Europe had more hunter-gatherer ancestry than their predecessors, but in Russia, the Yamnaya steppe herders of this time were descended not only from the preceding eastern European hunter-gatherers, but also from a population of Near Eastern ancestry. Western and Eastern Europe came into contact ∼4,500 years ago, as the Late Neolithic Corded Ware people from Germany traced ∼75% of their ancestry to the Yamnaya, documenting a massive migration into the heartland of Europe from its eastern periphery. This steppe ancestry persisted in all sampled central Europeans until at least ∼3,000 years ago, and is ubiquitous in present-day Europeans. These results provide support for a steppe origin of at least some of the Indo-European languages of Europe.
1,332 citations
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Harvard University1, Broad Institute2, Howard Hughes Medical Institute3, University College Dublin4, Emory University5, University of Copenhagen6, Trinity College, Dublin7, University of Adelaide8, Russian Academy of Sciences9, Complutense University of Madrid10, Rovira i Virgili University11, University of Valladolid12, University of Tübingen13, Max Planck Society14, Danube Private University15, University of Basel16, Hartwick College17, Pompeu Fabra University18
TL;DR: A genome-wide scan for selection using ancient DNA is reported, capitalizing on the largest ancient DNA data set yet assembled: 230 West Eurasians who lived between 6500 and 300 bc, including 163 with newly reported data.
Abstract: Ancient DNA makes it possible to observe natural selection directly by analysing samples from populations before, during and after adaptation events. Here we report a genome-wide scan for selection using ancient DNA, capitalizing on the largest ancient DNA data set yet assembled: 230 West Eurasians who lived between 6500 and 300 bc, including 163 with newly reported data. The new samples include, to our knowledge, the first genome-wide ancient DNA from Anatolian Neolithic farmers, whose genetic material we obtained by extracting from petrous bones, and who we show were members of the population that was the source of Europe's first farmers. We also report a transect of the steppe region in Samara between 5600 and 300 bc, which allows us to identify admixture into the steppe from at least two external sources. We detect selection at loci associated with diet, pigmentation and immunity, and two independent episodes of selection on height.
1,083 citations
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TL;DR: It is proposed that several Y. pestis lineages were established during the Bronze Age, some of which persist to the present day, and genomic evidence compatible with flea-mediated transmission causing bubonic plague is found.
Abstract: The origin of Yersinia pestis and the early stages of its evolution are fundamental subjects of investigation given its high virulence and mortality that resulted from past pandemics. Although the earliest evidence of Y. pestis infections in humans has been identified in Late Neolithic/Bronze Age Eurasia (LNBA 5000–3500y BP), these strains lack key genetic components required for flea adaptation, thus making their mode of transmission and disease presentation in humans unclear. Here, we reconstruct ancient Y. pestis genomes from individuals associated with the Late Bronze Age period (~3800 BP) in the Samara region of modern-day Russia. We show clear distinctions between our new strains and the LNBA lineage, and suggest that the full ability for flea-mediated transmission causing bubonic plague evolved more than 1000 years earlier than previously suggested. Finally, we propose that several Y. pestis lineages were established during the Bronze Age, some of which persist to the present day.
116 citations
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TL;DR: Genomic inference reveals that Scythians in the east and the west of the steppe zone can best be described as a mixture of Yamnaya-related ancestry and an East Asian component, and finds evidence that significant gene-flow from east to west Eurasia must have occurred early during the Iron Age.
Abstract: During the 1st millennium before the Common Era (BCE), nomadic tribes associated with the Iron Age Scythian culture spread over the Eurasian Steppe, covering a territory of more than 3,500 km in breadth. To understand the demographic processes behind the spread of the Scythian culture, we analysed genomic data from eight individuals and a mitochondrial dataset of 96 individuals originating in eastern and western parts of the Eurasian Steppe. Genomic inference reveals that Scythians in the east and the west of the steppe zone can best be described as a mixture of Yamnaya-related ancestry and an East Asian component. Demographic modelling suggests independent origins for eastern and western groups with ongoing gene-flow between them, plausibly explaining the striking uniformity of their material culture. We also find evidence that significant gene-flow from east to west Eurasia must have occurred early during the Iron Age.
88 citations
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Max Planck Society1, University of Tübingen2, Kazan Federal University3, Samara State University4, Russian Academy of Sciences5, Deutsches Archäologisches Institut6, Moscow State University7, Ludwig Maximilian University of Munich8, University of Florence9, Durham University10, University of Leicester11, Oeschger Centre for Climate Change Research12, University of Bern13, Hacettepe University14, University of Warwick15
TL;DR: Ancient Salmonella enterica genomes from Neolithic Eurasian humans compared with those from later archaeological contexts illuminate the evolving host specificity of the pathogen from an initial multi-mammalian adaptation towards an increasingly human specialization.
Abstract: 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 agropastoralists in western Eurasia that were up to 6,500 yr 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 5,000 yr. 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.
61 citations
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01 Jan 2010
TL;DR: In this paper, the authors show that hundreds of genetic variants, in at least 180 loci, influence adult height, a highly heritable and classic polygenic trait, revealing patterns with important implications for genetic studies of common human diseases and traits.
Abstract: Most common human traits and diseases have a polygenic pattern of inheritance: DNA sequence variants at many genetic loci influence the phenotype. Genome-wide association (GWA) studies have identified more than 600 variants associated with human traits, but these typically explain small fractions of phenotypic variation, raising questions about the use of further studies. Here, using 183,727 individuals, we show that hundreds of genetic variants, in at least 180 loci, influence adult height, a highly heritable and classic polygenic trait. The large number of loci reveals patterns with important implications for genetic studies of common human diseases and traits. First, the 180 loci are not random, but instead are enriched for genes that are connected in biological pathways (P = 0.016) and that underlie skeletal growth defects (P < 0.001). Second, the likely causal gene is often located near the most strongly associated variant: in 13 of 21 loci containing a known skeletal growth gene, that gene was closest to the associated variant. Third, at least 19 loci have multiple independently associated variants, suggesting that allelic heterogeneity is a frequent feature of polygenic traits, that comprehensive explorations of already-discovered loci should discover additional variants and that an appreciable fraction of associated loci may have been identified. Fourth, associated variants are enriched for likely functional effects on genes, being over-represented among variants that alter amino-acid structure of proteins and expression levels of nearby genes. Our data explain approximately 10% of the phenotypic variation in height, and we estimate that unidentified common variants of similar effect sizes would increase this figure to approximately 16% of phenotypic variation (approximately 20% of heritable variation). Although additional approaches are needed to dissect the genetic architecture of polygenic human traits fully, our findings indicate that GWA studies can identify large numbers of loci that implicate biologically relevant genes and pathways.
1,751 citations
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TL;DR: Some of the key events in the peopling of the world in the light of the findings of work on ancient DNA are reviewed.
Abstract: Ancient DNA research is revealing a human history far more complex than that inferred from parsimonious models based on modern DNA. Here, we review some of the key events in the peopling of the world in the light of the findings of work on ancient DNA.
1,365 citations
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University of Copenhagen1, University of Gothenburg2, Technical University of Denmark3, Leiden University4, Lund University5, University of Oxford6, University of Wrocław7, University of Zurich8, Wrocław Medical University9, University of Toronto10, Gorno-Altaisk State University11, South Ural State University12, Polish Academy of Sciences13, Ludwig Maximilian University of Munich14, Hungarian Natural History Museum15, Eötvös Loránd University16, Hungarian Academy of Sciences17, Masaryk University18, Academy of Sciences of the Czech Republic19, University of Tartu20, Yerevan State University21, University of Szeged22, Hungarian National Museum23, University of Wisconsin-Madison24, Russian Academy of Sciences25, First Faculty of Medicine, Charles University in Prague26, Armenian National Academy of Sciences27, Moscow State University28, University of California, Berkeley29
TL;DR: It is shown that the Bronze Age was a highly dynamic period involving large-scale population migrations and replacements, responsible for shaping major parts of present-day demographic structure in both Europe and Asia.
Abstract: The Bronze Age of Eurasia (around 3000-1000 BC) was a period of major cultural changes. However, there is debate about whether these changes resulted from the circulation of ideas or from human migrations, potentially also facilitating the spread of languages and certain phenotypic traits. We investigated this by using new, improved methods to sequence low-coverage genomes from 101 ancient humans from across Eurasia. We show that the Bronze Age was a highly dynamic period involving large-scale population migrations and replacements, responsible for shaping major parts of present-day demographic structure in both Europe and Asia. Our findings are consistent with the hypothesized spread of Indo-European languages during the Early Bronze Age. We also demonstrate that light skin pigmentation in Europeans was already present at high frequency in the Bronze Age, but not lactose tolerance, indicating a more recent onset of positive selection on lactose tolerance than previously thought.
1,088 citations
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Harvard University1, Broad Institute2, Howard Hughes Medical Institute3, University College Dublin4, Emory University5, Trinity College, Dublin6, University of Copenhagen7, University of Adelaide8, Russian Academy of Sciences9, Complutense University of Madrid10, Rovira i Virgili University11, University of Valladolid12, University of Tübingen13, Max Planck Society14, University of Basel15, Danube Private University16, Hartwick College17, Pompeu Fabra University18
TL;DR: A genome-wide scan for selection using ancient DNA is reported, capitalizing on the largest ancient DNA data set yet assembled: 230 West Eurasians who lived between 6500 and 300 bc, including 163 with newly reported data.
Abstract: Ancient DNA makes it possible to observe natural selection directly by analysing samples from populations before, during and after adaptation events. Here we report a genome-wide scan for selection using ancient DNA, capitalizing on the largest ancient DNA data set yet assembled: 230 West Eurasians who lived between 6500 and 300 bc, including 163 with newly reported data. The new samples include, to our knowledge, the first genome-wide ancient DNA from Anatolian Neolithic farmers, whose genetic material we obtained by extracting from petrous bones, and who we show were members of the population that was the source of Europe's first farmers. We also report a transect of the steppe region in Samara between 5600 and 300 bc, which allows us to identify admixture into the steppe from at least two external sources. We detect selection at loci associated with diet, pigmentation and immunity, and two independent episodes of selection on height.
1,083 citations
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TL;DR: The results indicate that diet-sensing, metabolism, and immune defense are important drivers of human-microbiome co-evolution.
774 citations