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Post by Admin on Feb 27, 2023 22:13:14 GMT
At least two genetically distinct groups of people made their way to Britain at the end of the last ice age, an analysis of the oldest human DNA discovered in the country has found. To make the discovery, researchers from University College London, the Natural History Museum and the Francs Crick Institute analysed the remains of two palaeolithic humans using radiocarbon dating and genome sequencing techniques. One, a female unearthed from Gough’s Cave in Somerset, was found to have lived around 15,000 years ago. She belonged to a group known for their use of stone tools and production of cave art, that moved through northern Europe around 16,000 years ago.  The other, a male found in Kendrick’s Cave, North Wales, lived around 13,500 years ago and belonged to a group known as western hunter-gatherers, who migrated to Britain around 14,000 years ago from the Near East. Around 17,000 years ago, as the last ice age was coming to an end, the climate in the UK began to warm. As temperatures increased, the glaciers that covered much of the country began to melt. The increasingly favourable conditions led to groups of palaeolithic humans to make their way to the UK from the continent. "The period we were interested in, from 20-10,000 years ago, is part of the Palaeolithic – the Old Stone Age. This is an important time period for the environment in Britain, as there would have been significant climate warming, increases in the amount of forest, and changes in the type of animals available to hunt," said Dr Sophy Charlton, formally of the Natural History Museum but now a lecturer in Bioarchaeology at the University of York. "There are very few human remains of this age in Britain; perhaps around a dozen individuals from six sites.” As well as differing genetically, the two groups also differed culturally, having different diets and ritualistic practices. “Chemical analyses of the bones showed that the individuals from Kendrick’s Cave ate a lot of marine and freshwater foods, including large marine mammals,” said study co-author Dr Rhiannon Stevens, from University College London’s Institute of Archaeology. “Humans at Gough’s Cave, however, showed no evidence of eating marine and freshwater foods, and primarily ate terrestrial herbivores such as red deer, bovids (such as wild cattle called aurochs) and horses.” In Kendrick’s Cave, decorated animal bones were found alongside the human remains, while Gough’s Cave contained cups made from modified human skulls – an indication of ritualistic cannibalism. Studying remains from other areas in the UK and across Europe is now needed to help fill out the picture further, the researchers say. "Finding the two ancestries so close in time in Britain, only a millennium or so apart, is adding to the emerging picture of Palaeolithic Europe, which is one of a changing and dynamic population," said Mateja Hajdinjak, Postdoctoral Research Fellow at the Francis Crick Institute. www.nature.com/articles/s41559-022-01883-z |
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Post by Admin on Mar 1, 2023 17:31:11 GMT
 Modern humans began to spread across Eurasia about 45,000 years ago, but previous research showed that the first modern humans that arrived in Europe did not contribute to later populations. A new study published in Nature Ecology & Evolution focuses on the people who lived between 35,000 and 5,000 years ago and that are, at least partially, the ancestors of the present-day population of Western Eurasia, including—for the first time—the genomes of people who lived during the Last Glacial Maximum (LGM), the coldest phase of the last Ice Age, around 25,000 years ago. The team analyzed the genomes of 356 prehistoric hunter gatherers from different archaeological cultures—including new data sets of 116 individuals from 14 different European and Central Asian countries. Climatic refugium or dead end? Surprisingly, the research team found that populations from different regions associated with the Gravettian culture, which was widespread across the European continent between 32,000 and 24,000 years ago, were not closely related to each other. They were linked by a common archaeological culture: they used similar weapons and produced similar portable art. Genetically, however, the populations from western and southwestern Europe (today's France and Iberia) differed from contemporaneous populations from central and southern Europe (today's Czech Republic and Italy).  Furthermore, the gene pool of the western Gravettian populations is found continuously for at least 20,000 years: their descendants who are associated with the Solutrean and Magdalenian cultures stayed in southwestern Europe during the coldest period of the last Ice Age (between 25,000 and 19,000 years ago) and later spread north-eastward to the rest of Europe. "With these findings, we can for the first time directly support the hypothesis that during the Last Glacial Maximum people found refuge in the climatically more favorable region of southwestern Europe," says first author Cosimo Posth. The Italian peninsula was previously considered to be another climatic refugium for humans during the LGM. However, the research team found no evidence for this, on the contrary: hunter-gatherer populations associated with the Gravettian culture and living in central and southern Europe are no longer genetically detectable after the LGM. People with a new gene pool settled in these areas, instead. "We find that individuals associated with a later culture, the Epigravettian, are genetically distinct from the area's previous inhabitants," says co-author He Yu. "Presumably, these people came from the Balkans, arrived first in northern Italy around the time of the glacial maximum and spread all the way south to Sicily." Large-scale genetic replacement The analyzed genomes also show that the descendants of these Epigravettian inhabitants of the Italian peninsula spread across the rest of Europe about 14,000 years ago, replacing populations associated with the Magdalenian culture. The research team describes a large-scale genetic replacement that may have been caused, in part, by climatic changes that forced people to migrate. "At that time, the climate warmed up quickly and considerably and forests spread across the European continent. This may have prompted people from the south to expand their habitat. The previous inhabitants may have migrated to the north as their habitat, the 'mammoth' steppe, dwindled," says Johannes Krause, the study's senior author.  Furthermore, the findings show that there had been no genetic exchange between contemporaneous hunter-gatherer populations in western and eastern Europe for more than 6,000 years. Interactions between people from central and eastern Europe can only be detected again from 8,000 years ago. "At that time, hunter-gatherers with distinct ancestries and appearances started to mix with each other. They were different in many aspects, including their skin and eye color," says He Yu. During this time agriculture and a sedentary lifestyle spread from Anatolia to Europe. "It is possible that the migration of early farmers into Europe triggered the retreat of hunter-gatherer populations to the northern edge of Europe. At the same time, these two groups started mixing with each other, and continued to do so for around 3,000 years," Krause says. "The data we gained from this study provides us with astonishingly detailed insights into the developments and encounters of West Eurasian hunter-gatherer groups," Posth summarizes. "Further interdisciplinary research will clarify which exact processes were responsible for the genetic replacements of entire Ice Age populations." More information: Cosimo Posth, Palaeogenomics of Upper Palaeolithic to Neolithic European hunter-gatherers, Nature Ecology & Evolution (2023). DOI: 10.1038/s41586-023-05726-0. www.nature.com/articles/s41586-023-05726-0 |
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Post by Admin on Mar 2, 2023 5:05:17 GMT
A 45,000-year-old leg bone from Siberia has yielded the oldest genome sequence for Homo sapiens on record — revealing a mysterious population that may once have spanned northern Asia. The DNA sequence from a male hunter-gatherer also offers tantalizing clues about modern humans’ journey from Africa to Europe, Asia and beyond, as well as their sexual encounters with Neanderthals. His kind might have remained unknown were it not for Nikolai Peristov, a Russian artist who carves jewellery from ancient mammoth tusks. In 2008, Peristov was looking for ivory along Siberia’s Irtysh River when he noticed a bone jutting from the riverbank. He dug it out and showed it to a police forensic scientist, who identified it as probably human. The bone turned out to be a human left femur, and eventually made it to the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, where researchers carbon-dated it. “It was quite fossilized, and the hope was that it might turn out old. We hit the jackpot,” says Bence Viola, a palaeoanthropologist who co-led the study of the remains. “It was older than any other modern human yet dated.” The luck continued when Viola’s colleagues found that the bone contained well-preserved DNA, and they sequenced its genome to the same accuracy as that achieved for contemporary human genomes (Q. Fu et al.Nature 514, 445–449; 2014).
From the extent of sharing of derived alleles between the Neanderthal and the Ust’-Ishim genomes we estimate the proportion of Neanderthal admixture in the Ust’-Ishim individual to be 2.3 6 0.3% (Supplementary Information section 16), similar to present-day east Asians (1.7–2.1%) and present-day Europeans (1.6–1.8%). Thus, admixture with Neanderthals had already occurred by 45,000 years ago. In contrast, we fail to detect any contribution from Denisovans, although such a contribution exists in present-day people not only in Oceania22,23, but to a lesser extent also in mainland east Asia12,24 (Supplementary Information section 17).
The DNA segments contributed by Neanderthals to the Ust’-Ishim individual are expected to be longer than such segments in presentday people as the Ust’-Ishim individual lived closer in time to when the admixture occurred, so there was less time for the segments to be fragmented by recombination. To test if this is indeed the case, we identified putative Neanderthal DNA segments in the Ust’-Ishim and presentday genomes based on derived alleles shared with the Neanderthal genome at positions where Africans are fixed for ancestral alleles. Figure 5 shows that fragments of putative Neanderthal origin in the Ust’-Ishim individual are substantially longer than those in present-day humans. We use the covariance in such derived alleles of putative Neanderthal origin across the Ust’-Ishim genome to infer that mean fragment sizes in the Ust’-Ishim genome are in the order of ,1.8–4.2 times longer than in present-day genomes and that the Neanderthal gene flow occurred 232–430 generations before the Ust’-Ishim individual lived (Supplementary Information section 18; Fig. 6). Under the simplifying assumption that the gene flow occurred as a single event, and assuming a generation time of 29 years16,25, we estimate that the admixture between the ancestors of the Ust’-Ishim individual and Neanderthals occurred approximately 50,000 to 60,000 years BP, which is close to the time of the major expansion of modern humans out of Africa and the Middle East. However, we also note that the presence of some longer fragments (Fig. 5) may indicate that additional admixture occurred even later. Nevertheless, these results suggest that the bulk of the Neanderthal contribution to present-day people outside Africa does not go back to mixture between Neanderthals and the anatomically modern humans who lived in the Middle East at earlier times; for example, the modern humans whose remains have been found at Skhul and Qafzeh26,
The researchers named their find Ust’-Ishim, after the district where Peristov found the remains. They dated him to between 43,000 and 47,000 years old, nearly twice the age of the next-oldest known complete modern-human genome, although older, archaic-human genomes exist. DNA may be the only chance to connect the remains to other humans. “This guy came out of nowhere — there’s no archaeology site we could connect it to,” says Viola, suggesting that his group roamed far and wide. The Ust’-Ishim man was probably descended from an extinct group that is closely related to humans who left Africa more than 50,000 years ago to populate the rest of the world, but later went extinct, Viola says. The most intriguing clue about his origin is that about 2% of his genome comes from Neanderthals. This is roughly the same level that lurks in the genomes of all of today’s non-Africans, owing to ancient trysts between their ancestors and Neanderthals. The Ust’-Ishim man probably got his Neanderthal DNA from these same matings, which, past studies suggest, happened after the common ancestor of Europeans and Asians left Africa and encountered Neanderthals in the Middle East. Until now, the timing of this interbreeding was uncertain — dated to between 37,000 and 86,000 years ago. But Neanderthal DNA in the Ust’-Ishim genome pinpoints it to between 50,000 and 60,000 years ago on the basis of the long Neanderthal DNA segments in the Ust’-Ishim man’s genome. Paternal and maternal chromosomes are shuffled together in each generation, so that over time the DNA segments from any individual become shorter.
Population relationships About 7.7 positions per 10,000 are heterozygous in the Ust’-Ishim 1genome, whereas between 9.6 and 10.5 positions are heterozygous in present-day Africans and 5.5 and 7.7 in present-day non-Africans (Sup-plementary Information section 12). Thus, with respect to genetic di-versity, the population to which the Ust’-Ishim individual belonged wasmore similar to present-day Eurasians than to present-day Africans,which probably reflects the out-of-Africa bottleneck shared by non-African populations. The Ust’-Ishim mtDNA sequence falls at the root of a large group of related mtDNAs (the ‘R haplogroup’), which occurs today across Eurasia (Supplementary Information section 8). The Ychromosome sequence of the Ust’-Ishim individual is similarly inferred to be ancestral to a group of related Y chromosomes (haplogroup K(xLT))that occurs across Eurasia today6(Supplementary Information section 9).As expected, the number of mutations inferred to have occurred on thebranch leading to the Ust’-Ishim mtDNA is lower than the numbers inferred to have occurred on the branches leading to related present-day mtDNAs (Supplementary Fig. 8.1). Using this observation and nine directly carbon-dated ancient modern human mtDNAs as calibrationpoints5,7in a relaxed molecular clock model, we estimate the age of the Ust’-Ishim bone to be ,49,000 yearsBP (95% highest posterior den-sity: 31,000–66,000 yearsBP), consistent with the radiocarbon date.In a principal component analysis of the Ust’-Ishim autosomal ge-nome along with genotyping data from 922 present-day individuals from 53 populations8(Fig. 2a), the Ust’-Ishim individual clusters with non-Africans rather than Africans. When only non-African popula-tions are analysed (Fig. 2b), the Ust’-Ishim individual falls close to zero on the two first principal component axes, suggesting that it does not share much more ancestry with any particular group of present-day humans.
The more precise dates for Neanderthal–human mating pose a challenge for scientists who have proposed that modern humans left Africa before 100,000 years ago and reached Asia more than 75,000 years ago, says Chris Stringer, a palaeoanthropologist at London’s Natural History Museum. Those researchers, who include Michael Petraglia, an archaeologist at the University of Oxford, UK, have pointed to H. sapiens-like bones from the Levant that are older than 100,000 years and to 70,000-year-old stone tools found in India as evidence for an early human exodus to Asia along a southern coastal route that eventually reached Oceania and Australia. But Petraglia sees Ust’-Ishim’s genome differently. “I think this is part of a population boom that’s going on around 45,000 years ago, which means modern humans got to the ends of the world by 45,000 years ago,” he says. Their numbers might have swamped human populations that arrived in earlier migrations.
the Ust’-Ishim genome shares more derived alleles with present-day people from East Asia than with present-day Europeans(jZj5 2.1–6.4).However, when an ,8,000-year-old genome from western Europe (LaBran˜a)9or a 24,000-year-old genome from Siberia (Mal’ta 1)10 were analysed, there is no evidence that the Ust’-Ishim genome shares more derived alleles with present-day East Asians than with these prehistoric individuals (jZj, 2). This suggests that the population to which the Ust’-Ishim individual belonged diverged from the ancestors of present-day West Eurasian and East Eurasian populations before—or simultaneously with—their divergence from each other. The finding that the Ust’-Ishim individual is equally closely related to present-day Asians and to 8,000-to 24,000-year-old individuals from western Eurasia, but not to present-day Europeans, is compatible with the hypothesis that present-day Europeans derive some of their ancestry from a population that did not participate in the initial dispersals of modern humans into Europeand Asia11.
Petraglia expects that ancient DNA and other fossil finds will paint a much more complicated picture of the peopling of Asia. “This is just a random find in a Siberian river deposit,” Stringer says. “What else could be there when they start looking systematically?”
A common model for the modern human colonization of Asia23,28 assumes that an early coastal migration gave rise to the present-day people of Oceania, while a later more northern migration gave rise to Europeans and mainland Asians. The fact that the 45,000-year-old individual from Siberia is not more closely related to the Onge from the Andaman Islands (putative descendants of an early coastal migration) than he is to present-day East Asians or Native Americans (putative descendants of a northern migration) (Fig. 3) shows that at least one other group to which the ancestors of the Ust’-Ishim individual belonged colonized Asia before 45,000 years ago. Interestingly, the Ust’-Ishim individual probably lived during a warm period (Greenland Interstadial 12) that has been proposed to be a time of expansion of modern humans into Europe29,30. However, the latter hypothesis is based only on the appearance of the so-called ‘Initial Upper Paleolithic’ industries (Supplementary Information section 5), and not on the identification of modern human remains31,32. It is possible that the Ust’-Ishim individual was associated with the Asian variant of Initial Upper Paleolithic industry, documented at sites such as Kara-Bom in the Altai Mountains at about 47,000 years BP. This individual would then represent an early modern human radiation into Europe and Central Asia that may have failed to leave descendants among present-day populations29.
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Post by Admin on Mar 3, 2023 3:41:58 GMT
Published in PLoS ONE, the findings reveal for the first time that multiple humid periods in ancient Iran led to the expansions of human populations, opening dispersal route across the region, and the possible interactions of species such as Neanderthals and our own Homo sapiens.  Professor Michael Petraglia, a key researcher in the study, said historic humid periods resulted in massive changes to ecosystems and led the team to identify large lakes in areas that were formerly deserts. "Conversely, during glacial periods this increased aridity would have led to the expansion of deserts, led to contractions, and the isolation of hominin populations," said Professor Petraglia, who is the Director of Griffith's Australian Research Center for Human Evolution. "This cycle of wetting and drying is shown for the first time in Iran." The research team, led by Ph.D. candidate Mohammad Javad Shoaee from the Max Planck Institute for Geoanthropology in Germany, found that during Marine Isotope Stage (MIS) 5, a warm, humid period beginning roughly 130,000 years ago, lakes and rivers enabled two pathways for human groups. One was a northern route through the Alborz and Kopet Dagh Mountains and north of the Dasht-I Kavir desert. The other route, first identified here, ran south along the Zagros Mountains before extending eastwards towards Pakistan and Afghanistan. The researchers also found evidence for a potential northern route during MIS 3, beginning about 57,000 years ago, which, given artifacts attributed to multiple tool making groups, could have permitted interactions between modern humans and Neanderthals.  "These findings highlight the importance of Iran for our species' dispersals out of Africa and ultimately around the globe," said Professor Petraglia. "As in other regions long considered too arid for early human occupations, such as the Arabian Peninsula, recent paleoclimatic research is changing how we understand the human story and the role that changing climates have played." "We recognized a new southern route along the Zagros Mountains and extending eastwards towards Pakistan and Afghanistan. We found evidence for a potential northern route during MIS 3, which would have permitted hominin movements and species interactions in Southwest Asia," Shoaee said. To find out how human groups made their way into Iran, the team developed the first spatially comprehensive, high resolution palaeohydrological model for Iran. They then compared their model, which showed when and where water was available, to the distribution of previously documented archaeological sites. The result was a clear relationship between the availability of water and the evidence of human presence. Not only does the current study help to explain the presence of previously documented sites, it also serves as a guide for future archaeological surveys in the region. "Our paleohydrological analyses identified 145,354km of rivers and 115 paleolakes calculated from 6,380 paleolake deposits. Only a handful of these paleolakes have so far been studied," Shoaee said. By focusing on regions where water once made human occupations possible, Professor Petraglia said "researchers could maximize the potential of finding archaeological sites." More information: Defining paleoclimatic routes and opportunities for hominin dispersals across Iran, PLoS ONE (2023). DOI: 10.1371/journal.pone.0281872 journals.plos.org/plosone/article?id=10.1371/journal.pone.0281872 |
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Post by Admin on Mar 15, 2023 17:36:27 GMT
 The migration of individuals from North Asia to North America across the Bering Sea is a well-established event in early human history. Despite this, the genetic composition of the people who inhabited North Asia during this time period has remained elusive due to a scarce number of ancient genomes obtained from this region. However, in a recent report published in Current Biology, researchers reveal genomes from ten individuals, some up to 7,500 years old, which shed light on this gap and demonstrate gene flow in the reverse direction, from North America to North Asia. The researchers’ analysis uncovers a previously undocumented group of early Holocene Siberian people who lived in the Neolithic Altai-Sayan region, located in close proximity to the intersection of Russia, China, Mongolia, and Kazakhstan. The genetic data reveals that they were descendants of both paleo-Siberian and Ancient North Eurasian (ANE) individuals. “We describe a previously unknown hunter-gatherer population in the Altai as early as 7,500 years old, which is a mixture between two distinct groups that lived in Siberia during the last Ice Age,” says Cosimo Posth at the University of Tübingen, Germany, and senior author of the study. “The Altai hunter-gatherer group contributed to many contemporaneous and subsequent populations across North Asia, showing how great the mobility of those foraging communities was.” Posth notes that the Altai region is known in the media as the location where a new archaic hominin group, the Denisovans, was discovered. But the region also has importance in human history as a crossroad for population movements between northern Siberia, Central Asia, and East Asia over millennia. Posth and colleagues report that the unique gene pool they uncovered may represent an optimal source for the inferred ANE-related population that contributed to Bronze Age groups from North and Inner Asia, such as Lake Baikal hunter-gatherers, Okunevo-associated pastoralists, and Tarim Basin mummies. They uncovered Ancient Northeast Asian (ANA) ancestry as well—which had initially been described in Neolithic hunter-gatherers from the Russian Far East—in another Neolithic Altai-Sayan individual associated with distinct cultural features. The findings reveal the spread of ANA ancestry about 1,500 kilometers farther to the west than previously observed. In the Russian Far East, they also identified 7,000-year-old individuals with Jomon-associated ancestry, indicating links with hunter-gatherer groups from the Japanese Archipelago. The data also are consistent with multiple phases of gene flow from North America to northeastern Asia over the last 5,000 years, reaching the Kamchatka Peninsula and central Siberia. The researchers note that the findings highlight a largely interconnected population throughout North Asia from the early Holocene onwards. “The finding that surprised me the most is from an individual dated to a similar period as the other Altai hunter-gatherers but with a completely different genetic profile, showing genetic affinities to populations located in the Russian Far East,” says Ke Wang at Fudan University, China, and lead author of the study. “Interestingly, the Nizhnetytkesken individual was found in a cave containing rich burial goods with a religious costume and objects interpreted as a possible representation of shamanism.” The genetic data from the Altai show that North Asia harbored highly connected groups as early as 10,000 years ago, across long geographic distances. “This suggests that human migrations and admixtures were the norm and not the exception also for ancient hunter-gatherer societies,” Posth says. Reference: “Middle Holocene Siberian genomes reveal highly connected gene pools throughout North Asia” by Ke Wang, He Yu, Rita Radzevičiūtė, Yuriy F. Kiryushin, Alexey A. Tishkin, Yaroslav V. Frolov, Nadezhda F. Stepanova, Kirill Yu. Kiryushin, Artur L. Kungurov, Svetlana V. Shnaider, Svetlana S. Tur, Mikhail P. Tiunov, Alisa V. Zubova, Maria Pevzner, Timur Karimov, Alexandra Buzhilova, Viviane Slon, Choongwon Jeong, Johannes Krause and Cosimo Posth, 12 January 2023, Current Biology. DOI: 10.1016/j.cub.2022.11.062 Summary The peopling history of North Asia remains largely unexplored due to the limited number of ancient genomes analyzed from this region. Here, we report genome-wide data of ten individuals dated to as early as 7,500 years before present from three regions in North Asia, namely Altai-Sayan, Russian Far East, and the Kamchatka Peninsula. Our analysis reveals a previously undescribed Middle Holocene Siberian gene pool in Neolithic Altai-Sayan hunter-gatherers as a genetic mixture between paleo-Siberian and ancient North Eurasian (ANE) ancestries. This distinctive gene pool represents an optimal source for the inferred ANE-related population that contributed to Bronze Age groups from North and Inner Asia, such as Lake Baikal hunter-gatherers, Okunevo-associated pastoralists, and possibly Tarim Basin populations. We find the presence of ancient Northeast Asian (ANA) ancestry—initially described in Neolithic groups from the Russian Far East—in another Neolithic Altai-Sayan individual associated with different cultural features, revealing the spread of ANA ancestry ∼1,500 km further to the west than previously observed. In the Russian Far East, we identify 7,000-year-old individuals that carry Jomon-associated ancestry indicating genetic links with hunter-gatherers in the Japanese archipelago. We also report multiple phases of Native American-related gene flow into northeastern Asia over the past 5,000 years, reaching the Kamchatka Peninsula and central Siberia. Our findings highlight largely interconnected population dynamics throughout North Asia from the Early Holocene onward. www.cell.com/current-biology/fulltext/S0960-9822(22)01892-9?_returnURL=https%3A%2F%2Flinkinghub.elsevier.com%2Fretrieve%2Fpii%2FS0960982222018929%3Fshowall%3Dtrue |
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