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Post by Admin on Feb 19, 2024 2:10:13 GMT
Thousands of years ago, the steep geologic folds of the Danube Gorges region, in present-day Romania and Serbia, were lushly forested and filled with game. The Danube River itself teemed with fish. It was an ideal home for the foragers who had lived there for millennia. But around 6200 B.C., foreigners began appearing. They came from the south and east, and hailed from farming communities, says anthropologist T. Douglas Price of the University of Wisconsin–Madison. Price recently analyzed strontium isotopes in 153 sets of human teeth from ancient burials in the Gorges. Strontium, which is present in the environment and becomes a permanent part of our tooth enamel in childhood, leaves a distinctive signature that lets scientists pinpoint an individual’s place of origin. The technique allowed Price and Dušan Borić, of Cardiff University, to document an influx of farmers into the area, including a number of women, who may have married into foraging groups. The work helps settle a decades-old debate about whether farming was brought to Europe by colonizers or diffused from community to community. “In Southeastern Europe,” Price says, “the colonization model is what’s going on.” According to a statement released by Lund University, DNA analysis of bone and teeth samples from prehistoric human remains unearthed in Denmark suggests that the first farmers to arrive in Scandinavia some 5,900 years ago wiped out the hunter-gatherer population within a few generations. “This transition has previously been presented as peaceful,” said Anne Birgitte Nielsen of Lund University. “However, our study indicates the opposite. In addition to violent death, it is likely that new pathogens from livestock finished off many gatherers,” she added. Then, some 4,850 years ago, seminomadic domestic cattle herders from southern Russia with Yamnaya ancestors entered Scandinavia and replaced those early farmers. This may have also occurred through violence and disease, Nielsen explained. Today’s Scandinavian population in Denmark can be traced to a mix of the Yamnaya and Eastern Europe’s Neolithic people. “We don’t have as much [ancient] DNA material from Sweden, but what there is points to a similar course of events,” Nielsen said. Read the original scholarly article about this research in Nature. The rise of farming in late Stone Age Europe was no smooth transition from hunter-gatherer lifestyles but a bloody takeover that saw nomadic populations wiped out by farmer-settlers in a few generations, a new study has found. In fact, twice in just a thousand years, the population of southern Scandinavia was entirely replaced by newcomers to the area, whose remains bear next to no trace of their predecessors in DNA profiles, analyzed by an international team of researchers. "This transition has previously been presented as peaceful," explains study author and palaeoecologist Anne Birgitte Nielsen of Lund University. "However, our study indicates the opposite. In addition to violent death, it is likely that new pathogens from livestock finished off many gatherers." Using a technique called shotgun sequencing, the team analyzed DNA samples from 100 human remains found in Denmark. The remains spanned 7,300 years of the Mesolithic period (or Middle Stone Age when hunter-gatherer lifestyles started to decline), the Neolithic period (or New Stone Age when humans settled into farming life), and the Early Bronze Age. Focusing on one specific region – that just so happens to have a climate suitable for both foraging and farming, and preserving human remains – allowed the researchers to map out the gene flows between populations, alongside changes in vegetation that reflect how they used the land. The analysis shows that around 5,900 years ago, a farmer population drove out the hunters, foragers, and fishers who had previously populated Scandinavia, and lopped forests to make farmland. Previous research (comparing DNA from a handful of skeletons) had suggested that these first Scandinavian farmers inherited around 30 percent of their genomes from hunter-gatherers, which would mean that their populations mixed – not that one wiped out the other. Plenty of archeological evidence suggests, instead, that this was a particularly violent time, and the new study shows that hunter-gatherer DNA was essentially erased, hardly detectable in the genomes of Scandinavia's first farmers. But their dominance was relatively short-lived. The farmers, also known as the Funnelbeaker culture, lived for about another 1,000 years before another wave of new arrivals from the eastern Steppes moved in. The newcomers carried with them their ancestry from the Yamnaya, a livestock-herding people with origins in southern Russia. They quickly replaced the Funnelbeakers, giving rise to a new cultural group called the Single Grave culture. "This time there was also a rapid population turnover, with virtually no descendants from the predecessors," Nielsen says, noting how the DNA profile of the first farmers to settle in Denmark has been essentially erased from modern-day Danish populations. "We don't have as much DNA material from Sweden, but what there is points to a similar course of events," Nielsen adds. Extensive archeological evidence unearthed before this study had chronicled this transition from the Funnelbeakers to the Single Grave culture, but the relationship between the two groups was often debated. Now, by better understanding the ancestry of Danish and Swedish people, researchers hope they may be able to uncover genetic markers in ancient DNA that could explain modern-day health patterns – in the same way that scientists just pinpointed why multiple sclerosis is more common among white, northern Europeans than their southern counterparts. "Our results help to enhance our knowledge of our heredity and our understanding of the development of certain diseases. Something that in the long term could be beneficial, for example in medical research," concludes Nielsen. The study has been published in Nature. www.nature.com/articles/s41586-023-06862-3
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Post by Admin on Feb 20, 2024 4:18:14 GMT
100 ancient genomes show repeated population turnovers in Neolithic Denmark
Abstract Major migration events in Holocene Eurasia have been characterized genetically at broad regional scales1,2,3,4. However, insights into the population dynamics in the contact zones are hampered by a lack of ancient genomic data sampled at high spatiotemporal resolution5,6,7. Here, to address this, we analysed shotgun-sequenced genomes from 100 skeletons spanning 7,300 years of the Mesolithic period, Neolithic period and Early Bronze Age in Denmark and integrated these with proxies for diet (13C and 15N content), mobility (87Sr/86Sr ratio) and vegetation cover (pollen). We observe that Danish Mesolithic individuals of the Maglemose, Kongemose and Ertebølle cultures form a distinct genetic cluster related to other Western European hunter-gatherers. Despite shifts in material culture they displayed genetic homogeneity from around 10,500 to 5,900 calibrated years before present, when Neolithic farmers with Anatolian-derived ancestry arrived. Although the Neolithic transition was delayed by more than a millennium relative to Central Europe, it was very abrupt and resulted in a population turnover with limited genetic contribution from local hunter-gatherers. The succeeding Neolithic population, associated with the Funnel Beaker culture, persisted for only about 1,000 years before immigrants with eastern Steppe-derived ancestry arrived. This second and equally rapid population replacement gave rise to the Single Grave culture with an ancestry profile more similar to present-day Danes. In our multiproxy dataset, these major demographic events are manifested as parallel shifts in genotype, phenotype, diet and land use.
Main The Mesolithic and Neolithic periods in southern Scandinavia are marked by a number of pivotal and well-described cultural transitions8. However, the genetic and demographic impacts of these events remain largely uncharacterized. The early postglacial human colonization of the Scandinavian peninsula (Sweden and Norway) is believed to comprise at least two distinct migration waves: a source related to western European hunter-gatherers (WHG) from the south, and an eastern European hunter-gatherer (EHG) source into the far north, before venturing south along the Atlantic coast of Norway9,10. However, insight into the fine-scale structure and mobility of Scandinavian Mesolithic populations is limited, including an almost complete absence of genetic data from southern Scandinavian populations associated with the consecutive Maglemose, Kongemose and Ertebølle cultures in Denmark.
The Neolithic transition represents a watershed event in European prehistory, marked by the spread of domesticated crops and livestock from Southwest Asia, starting around 11,000 BP. Although migrations and population turnovers associated with this transition have been demonstrated at broad geographical and chronological scales1,2,3,4, coarse sampling and a one-sided focus on genetics have hindered insights on social interaction and detailed demographic processes in the contact zones between locals and newcomers5,6,7. Southern Scandinavia occupies an enigmatic position in this discussion. The Neolithic transition was delayed here by a millennium compared to Central Europe, during which hunter-gatherer societies continued to flourish until around 5,900 calibrated years BP (cal. BP), only marginally affected by farmer populations to the south11. The substantial delay could suggest that the transition to farming in Denmark occurred by a different mechanism involving a stronger element of cultural diffusion12 than the migration of people (demic diffusion) observed in the rest of Europe13,14,15.
An extensive archaeological record has indicated that the Funnel Beaker culture (FBC) thrived for the first millennium of the Neolithic in Denmark, before an apparent decline16 was followed by the appearance of the Single Grave culture (SGC). Owing to a lack of genetic data and a robust absolute chronology, the relation between the FBC and the SGC has been extensively debated17,18,19. Population dynamics associated with this second cultural transition in Neolithic Denmark are similarly unresolved, including its possible link to the ‘steppe migrations’ that transformed the gene pools elsewhere in Europe around the same time1,2.
To investigate these defining events at high temporal and spatial resolution, we analyse a detailed and continuous dataset of 100 ancient Danish shotgun-sequenced genomes (0.01× to 7.1× autosomal coverage3), spanning about 7,300 years from the Early Mesolithic Maglemose, the Kongemose and Late Mesolithic Ertebølle epochs, the Early and Middle Neolithic FBC and the SGC, up until the Bronze Age (Fig. 1 and Supplementary Data 1). The archaeological record in Denmark represents a very large assemblage of well-documented Mesolithic and Neolithic human skeletal remains, from a wide range of chronological, topographical and socio-cultural contexts. This is a result of an environment and climate that was amenable to both Mesolithic fisher-hunter-gatherer lifeways20 and the later Neolithic farming practices, combined with taphonomically favourable preservation conditions for skeletal remains, and a long, prolific history of archaeological research. We used a multiproxy approach, combining autosomal imputed genomes3,21 with Y chromosomal and mitochondrial haplogroups, 14C-dating, genetic phenotype predictions, as well as 87Sr/86Sr, δ13C and δ15N isotope data as proxies for mobility and diet. Moreover, to investigate a direct link between demographic and environmental processes, we align the genetic changes observed in the Danish population over time with changes in local vegetation, based on pollen analyses and quantitative vegetation cover reconstruction.
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Post by Admin on Feb 24, 2024 20:47:00 GMT
Fig. 1: Overview of dataset. a, Geographic locations and age ranges relating to the 100 sequenced genomes from Denmark. Groupings are designated through a combination of chronology, culture, and ancestry (see Supplementary Notes 1 and 3). b, PCA for 179 ancient Danish individuals (Supplementary Data 3) ranging from the Mesolithic to the Viking Age, including previously published ones1,47,57,76, in the context of broader West Eurasian genetic diversity (n = 983 modern individuals, open grey circles; n = 1,105 ancient individuals, filled grey circles). Ancient individuals from Denmark are coloured according to the period as defined in a and c. c, Unsupervised model-based clustering (ADMIXTURE) for K = 8 ancestry components in Danish individuals, as well as contextual data from selected groups (left) that represent relevant ancestry components. See Extended Data Fig. 1 for individual labels. Black crosses indicate low-coverage genomes represented by pseudo-haploid genotypes. BA, Bronze Age. The Mesolithic period It is not known whether shifts in southern Scandinavian Mesolithic material culture occurred in a population continuum or were facilitated by incoming migrants. The Early Mesolithic settlement in Denmark is associated with the Maglemose culture (around 11,000–8,400 cal. BP), characterized archaeologically by small flint projectiles in geometric shapes. Until the recent development of underwater archaeology, this culture was known mainly from inland locations along lakes and rivers22. During the succeeding Kongemose culture (around 8,400–7,400 cal. BP), trapeze-shaped flint points dominate the assemblages of arrowheads23 along with high quality long blades. Most of the larger settlements cluster at good fishing locations along the coasts24, but there are also specialized hunting camps in the interior25. The Late Mesolithic Ertebølle culture (about 7,400–5,900 cal. BP), is characterized by flint points with transverse edges. Pottery was introduced from other hunter-gatherer groups to the east and perhaps the southwest26 and ‘exotic’ shaft-hole axes suggest exchange with farming societies south of the Baltic Sea27. The larger habitation sites, densely scattered along the coasts, probably represent multi-family, year-round occupation24,28 and they have provided important insights into the physical anthropology and spiritual culture of the period. By analysing genomes from 38 Danish hunter-gatherers and inferring their ancestry, we examine whether cultural transitions observed in the Danish archaeological record are associated with any genetic changes in the population. Model-based clustering (ADMIXTURE), PCA and IBD-sharing analyses show that throughout the Maglemose (n = 4), Kongemose (n = 8) and Ertebølle (n = 27) epochs the region displayed a remarkable genetic homogeneity across a 4,500-year transect (Figs. 1–3 and Extended Data Figs. 1–3), supporting interpretations of demographic continuity favoured by some archaeologists23,24,25. From the earliest known skeleton in Denmark, ‘Koelbjerg Man’ (NEO254, 10,648–10,282 cal. BP29), to the most recent Mesolithic skeleton included here, ‘Rødhals Man’ (NEO645, 5,916–5,795 cal. BP), the individuals derive their ancestry almost exclusively from the same southern European source (Italy_15000BP_9000BP) that predominated in WHG ancestry in Mesolithic Western Europe3.
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Post by Admin on Feb 26, 2024 19:42:33 GMT
Fig. 2: Identity-by-descent sharing patterns in ancient Danish individuals from circa 10,500–3000 cal. BP. Fig. 3: Genetic, phenotypic, dietary and environmental shifts in Denmark through time. Evidence of two population turnovers in chronologically sorted multiproxy data from 100 Danish Mesolithic, Neolithic and Early Bronze Age skeletons (Supplement Data 1). The figure shows concomitant changes in (from the top) admixture proportions in non-imputed genome-wide data, Y chromosomal and mitochondrial haplogroups, genetic phenotype predictions (based on imputed data) and 87Sr/86Sr and δ13C and δ15N isotope data as proxies for mobility and diet, respectively. Predicted height values represent differences (in cm) from the average height of the present-day Danish population; probabilities for the hair colours (blond, brown, black and red) and eye colours (blue and brown) are shown, with grey denoting probability of intermediate eye colour (including grey, green and hazel). Lower panel shows the quantitative changes in vegetation cover, based on pollen analyses at Lake Højby in Zealand. Note that the vegetation panel covers a shorter time interval than the other panels. Black vertical lines mark the first presence of Anatolian Neolithic farmer ancestry and Steppe-related ancestry, respectively. Individuals with low genomic coverage, signs of possible contamination and/or low genotype prediction score (GP) are indicated (Methods). In the IBD-based principal components analysis (PCA), the Danish Mesolithic individuals cluster closely together (Extended Data Fig. 4a), but beyond this tight local genetic connection they share most recent ancestry with the geographically and temporally proximate hunter-gatherer individuals from Western Europe (such as Cheddar Man, Loschbour and Bichon, commonly referred to as WHG; genetic cluster EuropeW_13500BP_8000BP; Fig. 2). A subtle shift of the earliest Danish individuals towards these western individuals probably reflects their closer temporal proximity captured through IBD sharing (Extended Data Fig. 4a). Although pressure-debitage of blades in the Maglemosian culture and pottery in the Ertebølle culture are both argued to have an eastern origin9,10,30,31, our data show no evidence for admixture with more eastern hunter-gatherers during those times. This points to cultural diffusion as the source of these introductions in Denmark. When tested with D-statistics, all Danish Mesolithic individuals form a clade with the earliest individual (NEO254), to the exclusion of Swedish Mesolithic hunter-gatherers (Sweden_10000BP_7500BP; Extended Data Fig. 2a) despite the close proximity to Sweden. However, a weak signal of gene flow with EHGs was shared across the whole Danish Mesolithic transect (Extended Data Fig. 2b), suggesting contact with communities further to the east prior to their expansion into Denmark before or during the earliest Mesolithic. Genetic phenotype predictions (Supplementary Note 2) indicate a high probability of blue eye pigmentation throughout the Mesolithic, consistent with previous findings1,15,32, showing that this feature was present already in the early Mesolithic but was not fixed in the population. The Mesolithic hunter-gatherers from Denmark all display high probability of brown or black hair and height predictions generally suggest slightly lower and/or less variable stature than in the succeeding Neolithic period. We caution, however, that the relatively large genetic distance to modern individuals included in the genome-wide association studies (GWAS) panel produces scores that are less applicable to Mesolithic individuals than to more recent groups33. Stable isotope δ13C values in collagen can inform on the proportion of marine versus terrestrially-derived protein, whereas δ15N values reflect the trophic level of the protein sources34. The earliest skeleton (NEO254) shows depleted dietary isotopic values (Fig. 3) representing a lifestyle of inland hunter-gatherers of the Early Mesolithic. This result is mirrored in the second earliest known skeleton from Denmark (Tømmerupgårds Mose34). From later Maglemose (around 9,500 cal. BP) and throughout the Kongemose and Ertebølle epochs, we observe gradually increased δ13C and δ15N values (Extended Data Fig. 5 and Supplementary Figs. 4.1 and 4.2). This implies that marine foods progressed to constitute the major supply of proteins, as suggested previously based on data from more than 30 Mesolithic humans and dogs, from both coastal and inland sites in Denmark34,35. During this period global sea-level rise gradually transformed present-day Denmark into an archipelago, where all human groups had ample access to coastal resources within their annual territories24. The local Mesolithic population adapted their diet and culture over time to the changing landscape and our data show that this occurred in a continuous population, without any detectable influx of migrants over a 4,500-year period. Low variability in 87Sr/86Sr isotope ratios throughout the Mesolithic (Fig. 3 and Supplementary Note 5) could indicate limited long-range mobility and/or deriving dietary sources from more homogeneous environments (for example, marine) than in the succeeding Neolithic periods. Notably, some of the Danish Mesolithic individuals proved to be closely related3. Close kinship is demonstrated in the case of two individuals (NEO568/NEO569), father and son, interred next to each other in the locus classicus shell midden site of Ertebølle, and in the case of two individuals (NEO732/NEO733), mother and daughter, that were buried together at Dragsholm. The Ertebølle grave was the first discovered human skeleton in Denmark (excavated in the 1890s) that indisputably represented hunter-gatherers. After the excavation of this site, academic reasoning rooted in Biblical narration about early prehistory in Scandinavia lost momentum. The excavation data cannot reveal whether they were buried simultaneously; it can be ascertained only that the boy (infant, less than two years of age) was positioned less than one metre from his father (the ‘Ertebølle Man’). Excavations at Dragsholm in 1973 uncovered a well-preserved double burial containing a grave with two Mesolithic women as well as a male grave with grave goods suggesting an Early Neolithic date for the latter36. A close kin relationship was suggested for the two Dragsholm women on the basis of physical anthropological observations37. It was suggested that they were sisters, but this can now be corrected to a co-burial of a mother and daughter. Our data also show that the male in the adjacent burial (‘Dragsholm Man’, NEO962) was not related to the two women. These cases show that close biological kinship was socially relevant to Late Mesolithic groups in Northern Europe and affected the mortuary treatment of dead members of their society.
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Post by Admin on Feb 28, 2024 21:17:11 GMT
Fig. 3: Genetic, phenotypic, dietary and environmental shifts in Denmark through time. Evidence of two population turnovers in chronologically sorted multiproxy data from 100 Danish Mesolithic, Neolithic and Early Bronze Age skeletons (Supplement Data 1). The figure shows concomitant changes in (from the top) admixture proportions in non-imputed genome-wide data, Y chromosomal and mitochondrial haplogroups, genetic phenotype predictions (based on imputed data) and 87Sr/86Sr and δ13C and δ15N isotope data as proxies for mobility and diet, respectively. Predicted height values represent differences (in cm) from the average height of the present-day Danish population; probabilities for the hair colours (blond, brown, black and red) and eye colours (blue and brown) are shown, with grey denoting probability of intermediate eye colour (including grey, green and hazel). Lower panel shows the quantitative changes in vegetation cover, based on pollen analyses at Lake Højby in Zealand. Note that the vegetation panel covers a shorter time interval than the other panels. Black vertical lines mark the first presence of Anatolian Neolithic farmer ancestry and Steppe-related ancestry, respectively. Individuals with low genomic coverage, signs of possible contamination and/or low genotype prediction score (GP) are indicated (Methods). In the IBD-based principal components analysis (PCA), the Danish Mesolithic individuals cluster closely together (Extended Data Fig. 4a), but beyond this tight local genetic connection they share most recent ancestry with the geographically and temporally proximate hunter-gatherer individuals from Western Europe (such as Cheddar Man, Loschbour and Bichon, commonly referred to as WHG; genetic cluster EuropeW_13500BP_8000BP; Fig. 2). A subtle shift of the earliest Danish individuals towards these western individuals probably reflects their closer temporal proximity captured through IBD sharing (Extended Data Fig. 4a). Although pressure-debitage of blades in the Maglemosian culture and pottery in the Ertebølle culture are both argued to have an eastern origin9,10,30,31, our data show no evidence for admixture with more eastern hunter-gatherers during those times. This points to cultural diffusion as the source of these introductions in Denmark. When tested with D-statistics, all Danish Mesolithic individuals form a clade with the earliest individual (NEO254), to the exclusion of Swedish Mesolithic hunter-gatherers (Sweden_10000BP_7500BP; Extended Data Fig. 2a) despite the close proximity to Sweden. However, a weak signal of gene flow with EHGs was shared across the whole Danish Mesolithic transect (Extended Data Fig. 2b), suggesting contact with communities further to the east prior to their expansion into Denmark before or during the earliest Mesolithic. Genetic phenotype predictions (Supplementary Note 2) indicate a high probability of blue eye pigmentation throughout the Mesolithic, consistent with previous findings1,15,32, showing that this feature was present already in the early Mesolithic but was not fixed in the population. The Mesolithic hunter-gatherers from Denmark all display high probability of brown or black hair and height predictions generally suggest slightly lower and/or less variable stature than in the succeeding Neolithic period. We caution, however, that the relatively large genetic distance to modern individuals included in the genome-wide association studies (GWAS) panel produces scores that are less applicable to Mesolithic individuals than to more recent groups33. Stable isotope δ13C values in collagen can inform on the proportion of marine versus terrestrially-derived protein, whereas δ15N values reflect the trophic level of the protein sources34. The earliest skeleton (NEO254) shows depleted dietary isotopic values (Fig. 3) representing a lifestyle of inland hunter-gatherers of the Early Mesolithic. This result is mirrored in the second earliest known skeleton from Denmark (Tømmerupgårds Mose34). From later Maglemose (around 9,500 cal. BP) and throughout the Kongemose and Ertebølle epochs, we observe gradually increased δ13C and δ15N values (Extended Data Fig. 5 and Supplementary Figs. 4.1 and 4.2). This implies that marine foods progressed to constitute the major supply of proteins, as suggested previously based on data from more than 30 Mesolithic humans and dogs, from both coastal and inland sites in Denmark34,35. During this period global sea-level rise gradually transformed present-day Denmark into an archipelago, where all human groups had ample access to coastal resources within their annual territories24. The local Mesolithic population adapted their diet and culture over time to the changing landscape and our data show that this occurred in a continuous population, without any detectable influx of migrants over a 4,500-year period. Low variability in 87Sr/86Sr isotope ratios throughout the Mesolithic (Fig. 3 and Supplementary Note 5) could indicate limited long-range mobility and/or deriving dietary sources from more homogeneous environments (for example, marine) than in the succeeding Neolithic periods.
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