Monday, October 24, 2022

UK’s oldest human DNA obtained, revealing two distinct Palaeolithic populations


The first genetic data from Palaeolithic human individuals in the UK - the oldest human DNA obtained from the British Isles so far - indicates the presence of two distinct groups that migrated to Britain at the end of the last ice age, finds new research.


The first genetic data from Palaeolithic human individuals in the UK - the oldest human DNA obtained from the British Isles so far - indicates the presence of two distinct groups that migrated to Britain at the end of the last ice age, according to new research.

Published today in Nature Ecology and Evolution, the new study by UCL Institute of Archaeology, the Natural History Museum and the Francis Crick Institute researchers reveals for the first time that the recolonisation of Britain consisted of at least two groups with distinct origins and cultures.

The study team explored DNA evidence from an individual from Gough’s Cave, Somerset, and an individual from Kendrick’s Cave, North Wales, who both lived more than 13,500 years ago. Very few skeletons of this age exist in Britain, with around a dozen found across six sites in total. The study, which involved radiocarbon dating and analysis as well as DNA extraction and sequencing, shows that it is possible to obtain useful genetic information from some of the oldest human skeletal material in the country.

The authors say that these genome sequences now represent the earliest chapter of the genetic history of Britain, but ancient DNA and proteins promise to take us back even further into human history.

The researchers found that the DNA from the individual from Gough’s Cave, who died about 15,000 years ago, indicates that her ancestors were part of an initial migration into northwest Europe around 16,000 years ago. However, the individual from Kendrick’s Cave is from a later period, around 13,500 years ago, with his ancestry from a western hunter-gatherer group. This group’s ancestral origins are thought to be from the near East, migrating to Britain around 14,000 years ago.

Study co-author Dr Mateja Hajdinjak (Francis Crick Institute) said: “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.”

The authors note that these migrations occurred after the last ice age when approximately two-thirds of Britain was covered by glaciers. As the climate warmed and the glaciers melted, drastic ecological and environmental changes took place and humans began to move back into northern Europe.

Study co-author Dr Sophy Charlton, who undertook the study whilst at the Natural History Museum, said: “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.”

As well as genetically, the two groups were found to be culturally distinct, with differences in what they ate and how they buried their dead.

Study co-author Dr Rhiannon Stevens (UCL Institute of Archaeology) said: “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.

“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.”

The researchers discovered that the mortuary practices of the two groups also differed. Although there were animal bones found at Kendrick’s Cave, these included portable art items, such as a decorated horse jawbone. No animal bones were found that showed evidence of being eaten by humans, and the scientists say that this indicates the cave was used as a burial site by its occupiers.

In contrast, animal and human bones found in Gough’s Cave showed significant human modification, including human skulls modified into ‘skull-cups’, which the researchers believe to be evidence for ritualistic cannibalism. Individuals from this earlier population seem to be the same people who created the Magdalenian stone tools, a culture known also for iconic cave art and bone artefacts.

Gough’s Cave is also the site where Britain’s famous Cheddar Man was discovered in 1903, dated to 10,564-9,915 years BP. In this study, Cheddar Man was found to have a mixture of ancestries, mostly (85%) western hunter-gatherer and some (15%) of the older type from the initial migration.

Co-author Dr Selina Brace (Natural History Museum) said: “We really wanted to find out more about who these early populations in Britain might have been.

“We knew from our previous work, including the study of Cheddar Man, that western hunter-gatherers were in Britain by around 10,500 years BP, but we didn’t know when they first arrived in Britain, and whether this was the only population that was present.”

Images available to download here


·     The human remains from Kendrick’s Cave are on display at Llandudno Museum by permission of Conwy County Borough Council, and from Gough’s Cave at the Natural History Museum, by permission of the Longleat Estate.

·     The deglacial (end of the last ice-age) began around 20,000 years ago.

·     Rapid climate warming occurred during the Late Glacial, which began ~14,700 years ago and ended at the start of the Holocene, ~11,700 years ago.

·     The early, southwest European ancestry described has been associated with Magdalenian-associated individuals closely related to those from sites such as El Mirón Cave, Spain, and Troisième Caverne in Goyet, Belgium.

·     Western hunter-gatherer ancestry has been associated with Epigravettian, Azilian/Federmesser, Epipalaeolithic and Mesolithic cultures.

·     Gough’s Cave is also where Britain’s famous Cheddar Man was found. Cheddar Man is dated to 10,564-9,915 years BP and interestingly in this study was found to have a mixture of ancestries, mostly (85%) western hunter-gatherer and but also some (15%) of the older southwest European ancestry.

Thursday, October 20, 2022

The Black Death shaped the evolution of immunity genes, setting the course for how we respond to disease today,

 An international team of scientists who analyzed centuries-old DNA from victims and survivors of the Black Death pandemic has identified key genetic differences that determined who lived and who died, and how those aspects of our immune systems have continued to evolve since that time.

 

Researchers from McMaster University, the University of Chicago, the Pasteur Institute and other organizations analyzed and identified genes that protected some against the devastating bubonic plague pandemic that swept through Europe, Asia and Africa nearly 700 years ago. Their study has been published today in the journal Nature.

 

The same genes that once conferred protection against the Black Death are today associated with an increased susceptibility to autoimmune diseases such as Crohn’s and rheumatoid arthritis, the researchers report.

 

The team focused on a 100-year window before, during and after the Black Death, which reached London in the mid-1300s.  It remains the single greatest human mortality event in recorded history, killing upwards of 50 per cent of the people in what were then some of the most densely populated parts of the world. 

 

More than 500 ancient DNA samples were extracted and screened from the remains of individuals who had died before the plague, died from it or survived the Black Death in London, including individuals buried in the East Smithfield plague pits used for mass burials in 1348-9.  Additional samples were taken from remains buried in five other locations across Denmark.

 

Scientists searched for signs of genetic adaptation related to the plague, which is caused by the bacterium Yersinia pestis.

 

They identified four genes that were under selection, all of which are involved in the production of proteins that defend our systems from invading pathogens and found that versions of those genes, called alleles, either protected or rendered one susceptible to plague.

 

Individuals with two identical copies of a particular gene, known as ERAP2, survived the pandemic at a much higher rates than those with the opposing set of copies, because the ‘good’ copies allowed for more efficient neutralization of Y. pestis by immune cells.  

 

“When a pandemic of this nature – killing 30 to 50 per cent of the population – occurs, there is bound to be selection for protective alleles in humans, which is to say people susceptible to the circulating pathogen will succumb. Even a slight advantage means the difference between surviving or passing. Of course, those survivors who are of breeding age will pass on their genes,” explains evolutionary geneticist Hendrik Poinar, an author of the Nature paper, director of McMaster’s Ancient DNA Centre, and a principal investigator with the Michael G. DeGroote Institute for Infectious Disease Research and McMaster’s Global Nexus for Pandemics & Biological Threats.

 

Europeans living at the time of the Black Death were initially very vulnerable because they had had no recent exposure to Yersinia pestis. As waves of the pandemic occurred again and again over the following centuries, mortality rates decreased.  

 

Researchers estimate that people with the ERAP2 protective allele (the good copy of the gene, or trait), were 40 to 50 per cent more likely to survive than those who did not. 

 

“The selective advantage associated with the selected loci are among the strongest ever reported in humans showing how a single pathogen can have such a strong impact to the evolution of the immune system,” says human geneticist Luis Barreiro, an author on the paper, and professor in Genetic Medicine at the University of Chicago.

 

The team reports that over time our immune systems have evolved to respond in different ways to pathogens, to the point that what had once been a protective gene against plague in the Middle Ages is today associated with increased susceptibility to autoimmune diseases. This is the balancing act upon which evolution plays with our genome.

 

"This highly original work has been possible only through a successful collaboration between very complementary teams working on ancient DNA, on human population genetics and the interaction between live virulent Yersinia pestis and immune cells,” says Javier Pizarro-Cerda, head of the Yersinia Research Unit and director of the World Health Organization Collaborating Centre for Plague at the Pasteur Institute. 

 

“Understanding the dynamics that have shaped the human immune system is key to understanding how past pandemics, like the plague, contribute to our susceptibility to disease in modern times,” says Poinar.

 

The findings, the result of seven years of work from graduate student Jennifer Klunk, formally of McMaster’s Ancient DNA Centre and postdoctoral fellow Tauras Vigylas, from the University of Chicago, allowed for an unprecedented look at the immune genes of victims of the Black Death.  

 


Wednesday, October 19, 2022

In medieval Norway, high-class people had stronger bones

 


Higher status individuals – especially women– were taller and had stronger bones, according to buried remains

Peer-Reviewed Publication


DXA-analysis: research on bone mineral density variation, as measured by Dual Energy X-Ray Absorptiometry. 

IMAGE: THE IMAGE SHOWS THE ORIENTATION OF THE PROXIMAL FEMUR AND STANDARDIZATION OF THE FEMUR DIAPHYSIS. view more 

CREDIT: ELIN T. BRØDHOLT, CC-BY 4.0 (HTTPS://CREATIVECOMMONS.ORG/LICENSES/BY/4.0/)

In medieval Norway, high status individuals tended to be taller and to have stronger bones, possibly as a result of a favorable lifestyle, according to a study published October 19, 2022 in the open-access journal PLOS ONE by Elin Brødholt of the University of Oslo and colleagues.

Throughout modern history, socioeconomic status has been linked to health and longevity, a relationship that can potentially be detected even in the skeletal remains of past cultures. Medieval Norway was a period characterized by notable levels of social stratification and poverty and is therefore a valuable case study in identifying correlations between social status and individual health.

The authors examined the remains of 227 individuals from five burial sites spanning the 11th through 16th centuries AD. Two of the sites, a royal church and a Dominican monastery, yielded the remains of high-status individuals, while the other three sites represented parish populations. For each individual, the researchers measured patterns of bone mineral density as well as stature and found significant skeletal differences between the socioeconomic groups.

In general, high-status individuals were taller and had higher bone mineral density compared with the parish populations. This pattern likely reflects differences in nutrition, activity level, and susceptibility to disease brought on by differing lifestyles between high-class and low-class individuals. These results were also influenced by other factors. For example, women showed more marked differences in skeletal traits between the socioeconomic groups as compared to men, possibly indicating that women in medieval Norway experienced a particularly high degree of lifestyle differences influenced by social class. These data are valuable in understanding the complex ways in which socioeconomic status has influenced health over the centuries.

The authors add: “Bone mineral density (BMD) has varied notably between archaeological populations and time periods in Scandinavia, and these exciting results demonstrate the effect of social inequality on skeletal BMD. By combining DXA-scanning and osteological analysis, we were able to elucidate new facts about life according to socioeconomic status in the medieval society of Norway.”

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In your coverage please use this URL to provide access to the freely available article in PLOS ONE: https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0275448

Citation: Brødholt ET, Gautvik KM, Günther C-C, Sjøvold T, Holck P (2022) Social stratification reflected in bone mineral density and stature: Spectral imaging and osteoarchaeological findings from medieval Norway. PLoS ONE 17(10): e0275448. https://doi.org/10.1371/journal.pone.0275448

Author Countries: Norway, Sweden

Funding: The authors received no specific funding for this work.

Meet the first Neandertal family

 

Ancient genomes of thirteen Neandertals provide a rare snapshot of their community and social organization

The first Neandertal draft genome was published in 2010. Since then, researchers from the Max Planck Institute for Evolutionary Anthropology have sequenced a further 18 genomes from 14 different archaeological sites throughout Eurasia. While these genomes have provided insights into the broader strokes of Neandertal history, we still know little of individual Neandertal communities.

To explore the social structure of Neandertals, the researchers turned their attention to southern Siberia, a region that has previously been very fruitful for ancient DNA research – including the discovery of Denisovan hominin remains at the famous Denisova Cave. From work done at that site, we know that Neandertals and Denisovans were present in this region over hundreds of thousands of years, and that Neandertals and Denisovans have interacted with each other – as the finding of a child with a Denisovan father and a Neandertal mother has shown.

First Neandertal community

In their new study, the researchers focused on the Neandertal remains in Chagyrskaya and Okladnikov Caves, which are within 100 kilometers of Denisova Cave. Neandertals briefly occupied these sites around 54,000 years ago, and multiple potentially contemporaneous Neandertal remains had been recovered from their deposits. The researchers  successfully retrieved DNA from 17 Neandertal remains – the largest number of Neandertal remains ever sequenced in a single study.

Chagyrskaya Cave has been excavated over the last 14 years by researchers from the Institute of Archaeology and Ethnography, Russian Academy of Sciences. Besides several hundred thousand stone tools and animal bones, they also recovered more than 80 bone and tooth fragments of Neandertals, one of the largest assemblages of these fossil humans not only in the region but also in the world.

The Neandertals at Chagyrskaya and Okladnikov hunted ibex, horses, bison and other animals that migrated through the river valleys that the caves overlook. They collected raw materials for their stone tools dozens of kilometers away, and the occurrence of the same raw material at both Chagyrskaya and Okladnikov Caves also supports the genetic data that the groups inhabiting these localities were closely linked.

Previous studies of a fossil toe from Denisova cave showed that Neandertals inhabited the Altai mountains considerably earlier as well, around 120,000 years ago. Genetic data shows though, that the Neandertals from Chagyrskaya and Okladnikov Caves are not descendants of these earlier groups, but are closer related to European Neandertals. This is also supported by the archaeological material: the stone tools from Chagyrskaya Cave are most similar to the so-called Micoquian culture known from Germany and Eastern Europe.

The 17 remains came from 13 Neandertal individuals – 7 men and 6 women, of which 8 were adults and 5 were children and young adolescents. In their mitochondrial DNA, the researchers  found several so-called heteroplasmies that were shared between individuals. Heteroplasmies are a special kind of genetic variant that only persists for a small number of generations.

The easternmost Neandertals

Among these remains were those of a Neandertal father and his teenage daughter. The researchers also found a pair of second degree relatives: a young boy and an adult female, perhaps a cousin, aunt or grandmother. The combination of heteroplasmies and related individuals strongly suggests that the Neandertals in Chagyrskaya Cave must have lived – and died – at around the same time.

“The fact that they were living at the same time is very exciting. This means that they likely came from the same social community. So, for the first time, we can use genetics to study the social organization of a Neandertal community,” says Laurits Skov, who is first author on this study.

Another striking finding is the extremely low genetic diversity within this Neandertal community, consistent with a group size of 10 to 20 individuals. This is much lower than those recorded for any ancient or present-day human community, and is more similar to the group sizes of endangered species at the verge of extinction.

However, Neandertals didn’t live in completely isolated communities. By comparing the genetic diversity on the Y-chromosome, which is inherited father-to-son, with the mitochondrial DNA diversity, which is inherited from mothers, the researchers could answer the question: Was it the men or the women who moved between communities? They found that the mitochondrial genetic diversity was much higher than the Y chromosome diversity, which suggests that these Neandertal communities were primarily linked by female migration. Despite the proximity to Denisova Cave, these migrations do not appear to have involved Denisovans – the researchers found no evidence of Denisovan gene flow in the Chagyrskaya Neandertals in the last 20,000 years before these individuals lived.

“Our study provides a concrete picture of what a Neandertal community may have looked like”, says Benjamin Peter, the last author of the study. “It makes Neandertals seem much more human to me.”

Tuesday, October 18, 2022

Neanderthals appear to have been carnivores

 A new study published on October 17th in the journal PNAS, led by a CNRS researcher, has for the first time used zinc isotope analysis to determine the position of Neanderthals in the food chain. Their findings suggest that they were in fact carnivores.

Were Neanderthals carnivores? Scientists have not yet settled the question. While some studies of the dental tartar of individuals from the Iberian Peninsula appear to show that they were major consumers of plants, other research carried out at sites outside Iberia seem to suggest that they consumed almost nothing but meat. Using new analytical techniques on a molar belonging to an individual of this species, researchers1 have shown that the Neanderthals at the Gabasa site in Spain appear to have been carnivores.

To determine an individual's position in the food chain, scientists have until now generally had to extract proteins and analyse the nitrogen isotopes present in the bone collagen. However, this method can often only be used in temperate environments, and only rarely on samples over 50,000 years old. When these conditions are not met, nitrogen isotope analysis is very complex, or even impossible. This was the case for the molar from the Gabasa site analysed in this study.

Given these constraints, Klevia Jaouen, a CNRS researcher, and her colleagues decided to analyse the zinc isotope ratios present in the tooth enamel, a mineral that is resistant to all forms of degradation. This is the first time this method has been used to attempt to identify a Neanderthal's diet. The lower the proportions of zinc isotopes in the bones, the more likely they are to belong to a carnivore. The analysis was also carried out on the bones of animals from the same time period and geographical area, including carnivores such as lynxes and wolves, and herbivores like rabbits and chamois. The results showed that the Neanderthal to whom this tooth from the Gabasa site belonged was probably a carnivore who did not consume the blood of their prey.

Broken bones found at the site, together with isotopic data, indicate that this individual also ate the bone marrow of their prey, without consuming the bones, while other chemical tracers show that they were weaned before the age of two. Analyses also show that this Neanderthal probably died in the same place they had lived in as a child.

Compared to previous techniques, this new zinc isotope analysis method makes it easier to distinguish between omnivores and carnivores. To confirm their conclusions, the scientists hope to repeat the experiment on individuals from other sites, especially from the Payre site in south-east France, where new research is under way.

 


New analysis of obsidian blades reveals dynamic Neolithic social networksf

 

 An analysis of obsidian artifacts excavated during the 1960s at two prominent archaeological sites in southwestern Iran suggests that the networks Neolithic people formed in the region as they developed agriculture are larger and more complex than previously believed, according to a new study by Yale researchers.


The study, published Oct. 17 in the journal Proceedings of the National Academy of Sciences, is the first to apply state-of-the-art analytical tools to a collection of 2,100 obsidian artifacts housed at the Yale Peabody Museum. The artifacts were unearthed more than 50 years ago at Ali Kosh and Chagha Sefid, sites on Iran’s Deh Luran Plain that yielded important archaeological discoveries from the Neolithic Era — the period beginning about 12,000 years ago when people began farming, domesticating animals, and establishing permanent settlements. 

Original analyses performed shortly after the artifacts were discovered had suggested people first acquired the obsidian — volcanic glass — from Nemrut Dağ, a now dormant volcano in Eastern Turkey, and then relied on an unknown second source for the material. This new elemental analysis showed the obsidian came from seven distinct sources, including Nemrut Dağ, in present-day Turkey and Armenia, which is as far as about 1,000 miles on foot from the excavation sites.

“It wasn’t a simple pattern of people obtaining obsidian from one source and then shifting to the next,” said Ellery Frahm, an archaeological scientist in the Department of Anthropology in Yale’s Faculty of Arts and Sciences, and the study’s lead author. “Rather, our analysis shows that they were acquiring obsidian from an increasingly diverse number of geological sources over time — a trend that was impossible to detect with the technology and methods available 50 years ago.”

The new analysis, combined with computer modeling, indicates that there were intensifying connections among Neolithic people, suggesting the presence of a greater number of settlements between the source volcanoes and the two sites where the artifacts were unearthed thousands of years later, Frahm said. 

The artifacts were collected in the 1960s during multiple excavations of the two sites led by Frank Hole, the C.J. MacCurdy Professor Emeritus of Anthropology at Yale. The initial analyses were based largely on the artifacts’ appearance, specifically their color when held up to sunlight. A subset of 28 artifacts were then subjected to an elemental analysis method common at the time that involved grinding them into powder.

Frahm and coauthor Christina M. Carolus, a doctoral student in the Department of Anthropology, are the first researchers to study the elemental composition of the obsidian artifacts since these early analyses. They used state-of-the-art portable X-ray fluorescence instruments, which allowed them to examine the entire collection without damaging the artifacts.   

“Every aspect of the discoveries made at these sites had been revisited since the 1960s except the elemental composition and sourcing of the obsidian artifacts,” Carolus said. “A lot more is known about the source volcanoes today than 50 years ago, and we know that sorting obsidian by color will miss a lot of nuances. Fortunately, we have instruments the size of cordless drills that, in a matter of seconds and without destroying material, give us a more accurate elemental signature than anything that was possible in the past.” 

Scientists widely believed that humanity’s transition from the hunter-gatherer lifestyle to agriculture produced a period of rapid population growth due to the increased birth rates made possible by enhanced food supplies and permanent settlements. Finding evidence of this demographic shift often requires excavating locations that include burial sites, which can indicate a given settlement’s population and provide a clearer picture of how agriculture allowed people to disperse across a landscape, Frahm said.

The researchers’ analysis of the obsidian provided similar evidence.

“Tracing these obsidian artifacts from their sources to their endpoints offers insight into how they moved from hand to hand to hand over time, which helps us better understand population changes in the region during the Neolithic Era,” Frahm said. “It suggested there were larger social networks and more settlements between the source volcanoes and the excavation sites than we previously thought.”