Wednesday, September 30, 2020

Neandertal gene variant increases risk of severe COVID-19



Research News

A study published in Nature shows that a segment of DNA that causes their carriers to have an up to three times higher risk of developing severe COVID-19 is inherited from Neandertals. The study was conducted by researchers at Karolinska Institutet and Max Planck Institute for Evolutionary Anthropology.

COVID-19 affects some people much more severely than others. Some reasons for this - such as old age - are already known, but other as yet unknown factors also play a role. This summer, a large international study linked a gene cluster on chromosome 3 to a higher risk of hospitalisation and respiratory failure upon infection with the SARS-CoV-2 virus.

Hugo Zeberg and Svante Pääbo at Karolinska Institutet in Sweden and Max Planck Institute for Evolutionary Anthropology in Germany now report that the version of the gene cluster associated with a higher risk of severe COVID-19 is very similar to the corresponding DNA sequences of a roughly 50,000-year-old Neandertal from Croatia, and indeed comes from Neandertals.

"It turns out that this gene variant was inherited by modern humans from the Neandertals when they interbred some 60,000 years ago," says Hugo Zeberg. "Today, the people who inherited this gene variant are three times more likely to need artificial ventilation if they are infected by the novel coronavirus SARS-CoV-2."

The study also reveals considerable differences in how common this genetic risk variant is in different parts of the world. It is particularly common among people in South Asia where about half of the population carry the Neandertal risk variant. In Europe, one in six people carry the risk variant, while in Africa and East Asia it is almost non-existent.

The study provides no explanation as to why this genetic variant confers a higher risk.

"It is striking that the genetic heritage from the Neandertals has such tragic consequences during the current pandemic. Why this is must now be investigated as quickly as possible," says Svante Pääbo, director at the Max Planck Institute for Evolutionary Anthropology.

Monday, September 28, 2020

Modern humans reached westernmost Europe 5,000 years earlier than previously known

Discovery may indicate modern humans and Neanderthals lived in the area concurrently


Research News

LOUISVILLE, Ky. - Modern humans arrived in the westernmost part of Europe 41,000 - 38,000 years ago, about 5,000 years earlier than previously known, according to Jonathan Haws, Ph.D., professor and chair of the Department of Anthropology at the University of Louisville, and an international team of researchers. The team has revealed the discovery of stone tools used by modern humans dated to the earlier time period in a report published this week in the journal Proceedings of the National Academy of Sciences.

The tools, discovered in a cave named Lapa do Picareiro, located near the Atlantic coast of central Portugal, link the site with similar finds from across Eurasia to the Russian plain. The discovery supports a rapid westward dispersal of modern humans across Eurasia within a few thousand years of their first appearance in southeastern Europe. The tools document the presence of modern humans in westernmost Europe at a time when Neanderthals previously were thought to be present in the region. The finding has important ramifications for understanding the possible interaction between the two human groups and the ultimate disappearance of the Neanderthals.

"The question whether the last surviving Neanderthals in Europe have been replaced or assimilated by incoming modern humans is a long-standing, unsolved issue in paleoanthropology," said Lukas Friedl, an anthropologist at the University of West Bohemia in Pilsen, Czech Republic, and project co-leader. "The early dates for Aurignacian stone tools at Picareiro likely rule out the possibility that modern humans arrived into the land long devoid of Neanderthals, and that by itself is exciting."

Until now, the oldest evidence for modern humans south of the Ebro River in Spain came from Bajondillo, a cave site on the southern coast. The discovery of stone stools characterized as Aurignacian, technology associated with early modern humans in Europe, in a secure stratigraphic context at Picareiro provide definitive evidence of early modern human arrival.

"Bajondillo offered tantalizing but controversial evidence that modern humans were in the area earlier than we thought," Haws said. "The evidence in our report definitely supports the Bajondillo implications for an early modern human arrival, but it's still not clear how they got here. People likely migrated along east-west flowing rivers in the interior, but a coastal route is still possible."

"The spread of anatomically modern humans across Europe many thousands of years ago is central to our understanding of where we came from as a now-global species," said John Yellen, program director for archaeology and archaeometry at the National Science Foundation, which supported the work. "This discovery offers significant new evidence that will help shape future research investigating when and where anatomically modern humans arrived in Europe and what interactions they may have had with Neanderthals."

The Picareiro cave has been under excavation for 25 years and has produced a record of human occupation over the last 50,000 years. An international research team from the Interdisciplinary Center for Archaeology and Evolution of Human Behavior (ICArEHB) in Faro, Portugal, is investigating the arrival of modern humans and extinction of Neanderthals in the region.

The project is led by Haws, Michael Benedetti of the University of North Carolina Wilmington, and Friedl, in collaboration with Nuno Bicho and João Cascalheira of the University of Algarve, where ICArEHB is housed, and Telmo Pereira of the Autonomous University of Lisbon.

With support from U.S. National Science Foundation grants to Haws and Benedetti, the team has uncovered rich archaeological deposits that include stone tools in association with thousands of animal bones from hunting, butchery and cooking activities.

Sahra Talamo of the University of Bologna, Italy, and the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, joined the research team to determine the age of the early modern human and Neanderthal occupations. She used state-of-the-art bone pretreatment and accelerator mass spectrometry (AMS) to date the bones that show evidence of butchery cut marks and intentional breakage by humans to extract bone marrow, a highly prized and nutritious food consumed by ancient people. The dating results place the modern human arrival to the interval between 41,000 and 38,000 years ago. The last Neanderthal occupation at the site took place between 45,000 and 42,000 years ago.

"The radiocarbon results from Lapa do Picareiro are not only very precise in terms of the dating method, but also demonstrate the meticulous work of the archeologists at the site," Talamo said. "The importance of collaboration between the radiocarbon specialist and the archaeologists is essential in order to obtain an accurate chronology like in the case of Picareiro."

Spatial analysis of high-resolution three-dimensional data confirmed the precise stratigraphic relationships between artifacts and radiocarbon samples and revealed discrete layers of occupation at the site.

"Analysis of high-resolution spatial data is crucial for documenting and observing lenses of human occupation and reconstructing occupational patterns, especially in cave environments where complex formation processes exist," said Grace Ellis, a Ph.D. student at Colorado State University studying landscape archaeology and ancient settlement patterns.

This was backed up by artifact refitting that showed the stone tools were not moved through post-depositional processes.

"Refitting is a task that requires a lot of time and patience, and in this case, it really was worthwhile because the results verified the geospatial observations," said Pereira, an archaeologist who specializes in stone technology.

While the dates suggest that modern humans arrived after Neanderthals disappeared, a nearby cave, Oliveira, has evidence for Neanderthals' survival until 37,000 years ago. The two groups may have overlapped for several thousand years in the area.

"If the two groups overlapped for some time in the highlands of Atlantic Portugal, they may have maintained contacts between each other and exchanged not only technology and tools, but also mates. This could possibly explain why many Europeans have Neanderthal genes," said Bicho, director of ICArEHB.

"Besides genetic and archeological evidence, high-resolution temporal context and fossil evidence across the continent is crucial for answering this question. With the preserved key layers dated to the transitional period, we are now awaiting human fossils to tell us more about the nature of the transition," Friedl said.

Despite the overlap in dates, there does not appear to be any evidence for direct contact between Neanderthals and modern humans. Neanderthals continued to use the same stone tools they had before modern humans arrived, bringing a completely different stone technology.

"Differences between the stone tool assemblages dated before and after about 41,000 years ago are striking at Picareiro," said Cascalheira, an ICArEHB board member and specialist on stone tool technology. "Older levels are dominated by quartzite and quartz raw materials and marked by the presence of Levallois technology, a typical element of Neanderthal occupations in Europe. Aurignacian levels, on the other hand, are dominated by flint and the production of very small blades that were likely used as inserts in arrow shafts for hunting."

Flint also was used to make tools for butchering animals such as red deer, ibex and possibly rabbits. The team recovered a few red deer canine teeth, often used as personal adornments, but so far these do not show traces of manufacturing jewelry.

"The bones from Lapa do Picareiro make up one of the largest Paleolithic assemblages in Portugal, and the preservation of these animal bones is remarkable," said Milena Carvalho, a Ph.D. candidate at the University of New Mexico and ICArEHB researcher studying the diets and paleoecology of Neanderthals and modern humans. "The collection will provide tremendous amounts of information on human behavior and paleoecology during the Paleolithic and we will be studying it for decades."

The cave sediments also contain a well-preserved paleoclimatic record that helps reconstruct environmental conditions at the time of the last Neanderthals and arrival of modern humans.

"We studied changes in the size of limestone clasts and the chemistry of muddy fine sediment filling the cave to understand the paleoclimatic context for the transition," Benedetti said. "Our analysis shows that the arrival of modern humans corresponds with, or slightly predates, a bitterly cold and extremely dry phase. Harsh environmental conditions during this period posed challenges that both modern human and Neanderthal populations had to contend with."

The cave itself has an enormous amount of sediment remaining for future work and the excavation still hasn't reached the bottom.

"I've been excavating at Picareiro for 25 years and just when you start to think it might be done giving up its secrets, a new surprise gets unearthed," Haws said. "Every few years something remarkable turns up and we keep digging."

Thursday, September 24, 2020

Y chromosomes of Neandertals and Denisovans now sequenced


Neandertals have adopted male sex chromosome from modern humans


Research News

In 1997, the very first Neandertal DNA sequence - just a small part of the mitochondrial genome - was determined from an individual discovered in the Neander Valley, Germany, in 1856. Since then, improvements in molecular techniques have enabled scientists at the Max Planck Institute for Evolutionary Anthropology to determine high quality sequences of the autosomal genomes of several Neandertals, and led to the discovery of an entirely new group of extinct humans, the Denisovans, who were relatives of the Neandertals in Asia.

However, because all specimens well-preserved enough to yield sufficient amounts of DNA have been from female individuals, comprehensive studies of the Y chromosomes of Neandertals and Denisovans have not yet been possible. Unlike the rest of the autosomal genome, which represents a rich tapestry of thousands of genealogies of any individual's ancestors, Y chromosomes have a peculiar mode of inheritance - they are passed exclusively from father to son. Y chromosomes, and also the maternally-inherited mitochondrial DNA, have been extremely valuable for studying human history.

New method to identify Y chromosome molecules

In this study, the researchers identified three male Neandertals and two Denisovans that were potentially suitable for DNA analysis, and developed an approach to fish out human Y chromosome molecules from the large amounts of microbial DNA that typically contaminate ancient bones and teeth. This allowed them to reconstruct the Y chromosome sequences of these individuals, which would not have been possible using conventional approaches.

By comparing the archaic human Y chromosomes to each other and to the Y chromosomes of people living today, the team found that Neandertal and modern human Y chromosomes are more similar to one another than they are to Denisovan Y chromosomes. "This was quite a surprise to us. We know from studying their autosomal DNA that Neandertals and Denisovans were closely related and that humans living today are their more distant evolutionary cousins. Before we first looked at the data, we expected that their Y chromosomes would show a similar picture," says Martin Petr, the lead author of the study. The researchers also calculated that the most recent common ancestor of Neandertal and modern human Y chromosomes lived around 370,000 years ago, much more recently than previously thought.

It is by now well established that all people with non-African ancestry carry a small amount of Neandertal DNA as a result of interbreeding between Neandertals and modern humans approximately 50,000-70,000 years ago, quite shortly after modern humans migrated out of Africa and started spreading around the world. However, whether Neandertals might also carry some modern human DNA has been a matter of some debate.

These Y chromosome sequences now provide new evidence that Neandertals and early modern humans met and exchanged genes before the major out of Africa migration - potentially as early as 370,000 years ago and certainly more than 100,000 years ago. This implies that some population closely related to early modern humans must already have been in Eurasia at that time. Surprisingly, this interbreeding resulted in the replacement of the original Neandertal Y chromosomes with those of early modern humans, a pattern similar to what has been seen for Neandertal mitochondrial DNA in an earlier study.

Selection for Y chromosomes from early modern humans

At first, the complete replacement of both Y chromosomes and mtDNA of early Neandertals was puzzling, as such replacement events are quite unlikely to occur by chance alone. However, the researchers used computer simulations to show that the known small size of Neandertal populations may have led to an accumulation of deleterious mutations in their Y chromosomes which would reduce their evolutionary fitness. This is quite similar to situations where extremely small population sizes and inbreeding can sometimes increase the incidence of some diseases. "We speculate that given the important role of the Y chromosome in reproduction and fertility, the lower evolutionary fitness of Neandertal Y chromosomes might have caused natural selection to favor the Y chromosomes from early modern humans, eventually leading to their replacement" says Martin Petr.

Janet Kelso, the senior author of the study, is optimistic that this replacement hypothesis could be tested in the near future: "If we can retrieve Y chromosome sequences from Neandertals that lived prior to this hypothesized early introgression event, such as the 430,000 year old Neandertals from Sima de los Huesos in Spain, we predict that they would still have the original Neandertal Y chromosome and will therefore be more similar to Denisovans than to modern humans."

Tuesday, September 22, 2020

Wild birds as offerings to the Egyptian gods



Research News




Millions of ibis and birds of prey mummies, sacrificed to the Egyptian gods Horus, Ra or Thoth, have been discovered in the necropolises of the Nile Valley. Such a quantity of mummified birds raises the question of their origin: were they bred, like cats, or were they hunted? Scientists from the CNRS, the Université Claude Bernard Lyon 1 and the C2RMF (1) have carried out extensive geochemical analyses on mummies from the Musée des Confluences, Lyon. According to their results, published on 22nd September 2020 in the journal Scientific Reports, they were wild birds.

Mammals, reptiles, birds: the tens of millions of animal mummies deposited as offerings in the necropolises of the Nile Valley bear witness to an intense religious fervour, and to the practices of collecting and preparing animals that undoubtedly contributed significantly to the economy from the Old Kingdom (3rd millennium BC) to Roman Egypt (1st-3rd centuries AD). However, the origin of these animals and the methods of supply remain unknown. For some tamed species, such as the cat, breeding was probably the most efficient way of supplying large numbers of animals for mummification. But unlike cats, bird mummies cover all stages of development, from egg to adult, which may indicate more opportunistic sourcing practices.

In order to determine the origin -- breeding or hunting -- of the mummified birds, tiny fragments of feathers, bones and embalming strips were taken from 20 ibis and birds of prey mummies from the collections of the Musée des Confluences, Lyon. If these birds, which migrate in the wild, had been bred, their diet would have been homogeneous, of local origin and reflected in the uniform isotopic composition (2) of the animal remains, regardless as to whether that diet had been produced specifically or derived from that of coexisting humans.

The various tissues were therefore dated using the carbon-14 method; and the isotopic compositions of oxygen, carbon, nitrogen, sulfur and strontium were measured, interpreted in terms of food sources and compared with those of contemporaneous human mummies. However, far from being homogeneous, these isotopic compositions showed a high variability and "exotic" signatures compared to those of ancient Egyptian humans: the birds were wild, migrating seasonally out of the Nile Valley.

These results, combined with that of a genetic study carried out by another team (3), suggest the mass hunting and capture of birds as documented on certain tomb frescoes (for example on the wall of Nakht's tomb in the Theban Necropolis). Indeed, the Egyptians probably exerted a significant ecological pressure on wild bird populations long before the decline in avifauna observed today.

Monday, September 21, 2020

Archaeology uncovers infectious disease spread in Asia - 4000 years ago

 New bioarchaeology research from a University of Otago PhD candidate has shown how infectious diseases may have spread 4000 years ago, while highlighting the dangers of letting such diseases run rife.

Yaws - from the same bacteria species responsible for syphilis (Treponema pallidum) - is a childhood disease causing highly infectious skin lesions. It is spread via touch from person to person and, in advanced cases, can leave sufferers with severe bone disfigurement. While it is easily curable in its early stages, the bone disfigurements are irreversible.

The disease has been eradicated from much of the world but is still prevalent in the Western Pacific, affecting some 30,000 people. A previous global attempt to eradicate this tropical disease failed at the last hurdle in the 1950's and a new attempt was curtailed by the COVID-19 outbreak, University of Otago Department of Anatomy PhD candidate Melandri Vlok says.

Ms Vlok's PhD research uses archaeology to shed light on the spread of diseases when different human populations interact for the first time. Her specific interest is in what she calls the "friction zone", where ancient agricultural people met hunter gatherer people.

In 2018 she travelled to Vietnam to study skeletal remains from the Man Bac archaeological site. From the Ninh Bình Province in the north of the country, Man Bac was excavated in 2005 and 2007 and has delivered a treasure trove of information for archaeologists thanks to its role during the transition away from foraging to farming in Mainland Southeast Asia.

Now housed in Hanoi's Institute of Archaeology those remains are well-studied but had not been analysed for evidence of yaws, Ms Vlok says.

Her supervisor at Otago, renowned bioarchaeologist Professor Hallie Buckley, had seen what she thought might be yaws on a photograph of Man Bac remains. Professor Buckley travelled with Ms Vlok and together with a passionate team of experts from Vietnam they confirmed their suspicions, Ms Vlok says. Later, Ms Vlok found a second example of the disease.

This was significant, as the Man Bac site dates back 4000 years. Till now, there was no strong evidence for yaws in prehistoric Asia.

Ms Vlok's research suggests yaws was introduced to hunter-gathers in present-day Vietnam by an agricultural population moving south from modern-day China. These hunter-gathers descended from the first people out of Africa and into Asia who also eventually inhabited New Guinea, the Solomon Islands and Australia.

The farmers had been in China for at least 9000 years but it wasn't until around 4000 years ago farming was introduced to Southeast Asia. It is possible this movement of people brought diseases, including yaws, at the same time.

Ms Vlok says the length of time the disease has existed in the region is relevant when addressing how hard it has been to eradicate.

"This matters, because knowing more about this disease and its evolution, it changes how we understand the relationship people have with it. It helps us understand why it's so difficult to eradicate. If it's been with us thousands of years it has probably developed to fit very well with humans."

This year's COVID-19 pandemic has focused people's attention on infectious diseases, and there are lessons to be learned from the past, Ms Vlok says.

"Archaeology like this is the only way to document how long a disease has been with us and been adapting to us. We understand with COVID-19 today how fantastic that disease is at adapting to humans. And Treponema has been with us for so much longer.

"So, this shows us what happens when we don't take action with these diseases. It's a lesson of what infectious diseases can do to a population if you let them spread widely. It highlights the need to intervene, because sometimes these diseases are so good at adapting to us, at spreading between us."

Friday, September 18, 2020

A 48,000 years old tooth that belonged to one of the last Neanderthals in Northern Italy




A milk-tooth found in the vicinity of "Riparo del Broion" on the Berici Hills in the Veneto region bears evidence of one of the last Neanderthals in Italy. This small canine tooth belonged to a child between 11 and 12 that had lived in that area around 48,000 years ago. This is the most recent Neanderthal finding in Northern Italy.

The study uncovering this tooth was carried out by a group of researchers from the Universities of Bologna and Ferrara, who have recently published a paper in the Journal of Human Evolution. "This work stems from the synergy between different disciplines and specializations", says Matteo Romandini, lead author of this study and researcher at the University of Bologna. "High-resolution prehistoric field-archaeology allowed us to find the tooth, then we employed virtual approaches to the analyses of its shape, genome, taphonomy and of its radiometric profile. Following this process, we could identify this tooth as belonging to a child that was one of the last Neanderthals in Italy".

The genetic analysis reveals that the owner of the tooth found in Veneto was a relative, on their mother's side, of Neanderthals that had lived in Belgium. This makes this site in Veneto a key-area for comprehending the gradual extinction of Neanderthals in Europe.

"This small tooth is extremely important", according to Stefano Benazzi, professor at the University of Bologna and research coordinator. "This is even more relevant if we consider that, when this child who lived in Veneto lost their tooth, Homo Sapiens communities were already present a thousand kilometres away in Bulgaria".

Researchers analysed the tooth by employing highly innovative virtual methods. "The techniques we employed to analyse the tooth led to the following discovery: this is an upper canine milk-tooth that belonged to a Neanderthal child, aged 11 or 12, that lived between 48,000 and 45,000 years ago", as report Gregorio Oxilia and Eugenio Bortolini, who are co-authors of the study and researchers at the University of Bologna. "According to this dating, this little milk-tooth is the most recent finding of the Neanderthal period in Northern Italy and one of the latest in the entire peninsula".

The findings retrieved from the "Riparo del Broion" are still being analysed. However, preliminary results show that this site had been used for a long period of time as there are signs of hunting activities and butchering of large prays. "The manufacturing of tools, mainly made of flint, shows Neanderthals' great adaptability and their systematic and specialized exploitation of the raw materials available in this area", adds Marco Peresanti, a professor of the University of Ferrara who contributed to the study.

Ancient human footprints in Saudi Arabia give glimpse of Arabian ecology 120000 years ago


Situated between Africa and Eurasia, the Arabian Peninsula is an important yet understudied region for understanding human evolution across the continents. Recent research highlighting the role of the Arabian Peninsula in human prehistory shows that humans repeatedly dispersed into the peninsula's interior at times when its harsh deserts were transformed into lush grasslands. However, the nature and timing of these dispersals have remained elusive, due to a scarcity of datable material and poor-resolution paleoecological data associated with evidence for humans.

In a new study published in Science Advances, researchers from the Max Planck Institutes for Chemical Ecology (MPI-CE) and the Science of Human History (MPI-SHH) in Jena, Germany and Royal Holloway University of London, UK, together with a team of international partners, describe a large assemblage of fossilized footprints discovered in an ancient lake deposit in Saudi Arabia's Nefud Desert. The footprints, dated to roughly 120 thousand-years-ago, include those of humans, elephants and horses, among other animals. These findings represent the earliest dated evidence for human movements into this part of the world, contemporary with well-known human dispersals from Africa to the Levant. In addition, it appears that the movements and landscape use patterns of humans and large mammals were tightly linked, perhaps in response to dry conditions and diminishing water supplies.

A Green Arabia in Human Prehistory

Because the Arabian Peninsula is characterized by large, hyper-arid deserts inhospitable to early humans and the animals they relied on, Arabia has received considerably less attention than Africa or Eurasia, neighboring regions that are vital to understanding human prehistory. However, research over the last decade has shown that this was not always the case, and it is now well-understood that conditions in Arabia have fluctuated significantly over the past million years.

"At certain times in the past, the deserts that dominate the interior of the peninsula transformed into expansive grasslands with permanent freshwater lakes and rivers," explains Richard Clark-Wilson of Royal Holloway, one of the lead authors of the study. "It was during these periods of climatic upturn that human and animal populations dispersed into the interior, as shown by the archaeological and fossil record."

Footprints as a High-Resolution Proxy

The footprints described in the new study were discovered during a recent survey of the Nefud Desert in Saudi Arabia. At an ancient lake deposit dubbed 'Alathar' (meaning "the trace" in Arabic) by the team, hundreds of human and animal footprints were discovered embedded in the surface, having been exposed following the erosion of overlying sediments.

"We immediately realized the potential of these findings," says Mathew Stewart of MPI-CE, one of the study's lead authors. "Footprints are a unique form of fossil evidence in that they provide snapshots in time, typically representing a few hours or days, a resolution we tend not get from other records."

Researchers were able to identify a number of animals from the footprints, including elephants, horses, and camels. The presence of elephants was particularly notable, as these large animals appear to have gone locally extinct in the Levant by around 400 thousand-years-ago.

"The presence of large animals such as elephants and hippos, together with open grasslands and large water resources, may have made northern Arabia a particularly attractive place to humans moving between Africa and Eurasia," says Michael Petraglia of MPI-SHH, who has been conducting research in the region for over a decade.

The dense concentration of footprints and evidence from the lake sediments suggests that animals may have been congregating around the lake in response to dry conditions and diminishing water supplies. Humans, too, may have been utilizing the lake for water and the surrounding area for foraging.

"We know people visited the lake, but the lack of stone tools or evidence of the use of animal carcasses suggests that their visit to the lake was only brief," says Stewart. Human movements and landscape use patterns, therefore, may have been closely linked to the large animals they shared the area with.

Early Human Dispersals into Arabia

The age of the footprints is of particular interest. They date to a period known as the last interglacial, a time of relatively humid conditions across the region and an important moment in human prehistory. Environmental changes during the last interglacial would have allowed humans and animals to disperse across otherwise desert regions, which normally acted as major barriers to dispersal during the less humid periods. Fossil and archaeological records indicate that these conditions also facilitated human dispersal from Africa into the Levant.

"It is only after the last interglacial with the return of cooler conditions that we have definitive evidence for Neanderthals moving into the region," says Stewart. "The footprints, therefore, most likely represent humans, or Homo sapiens."

These findings suggest that human movements beyond Africa during the last interglacial extended into northern Arabia, highlighting the importance of Arabia for the study of human prehistory.

Wednesday, September 16, 2020

Ancient DNA shows domestic horses were introduced in the southern Caucasus and Anatolia during the Bronze Age

Domestic horses likely did not originate in Anatolia as previously suspected, according to a new study of ancient horse remains dating as far back as 9000 BCE. Instead, they may have been introduced to the peninsula - which makes up most of modern-day Turkey - and the nearby Caucasus region from the Eurasian Steppe by about 2000 BCE, during the Bronze Age. The findings also suggest imported domestic horses were bred with local wild Anatolian horses and donkeys and provide the earliest genomic evidence for a mule in southwest Asia, dating to between 1100 and 800 BCE. Domestication of horses about 5,500 years ago forever changed transportation, trade, warfare, and migration. But despite their transformative role in human history, it remains unclear where, when, and how many times horses were domesticated. In recent years, careful recovery of horse remains from well-preserved archaeological sites in Anatolia and neighboring areas together with progress in paleogenetic approaches has made it possible to specifically address the processes responsible for the origins of domestic horses in this part of western Asia. To explore whether Anatolia might have been this mysterious point of origin, Silvia Guimaraes and colleagues analyzed more than 100 equid remains from 8 sites in central Anatolia and 6 sites in the Caucasus dating mostly from the Early Neolithic to the Iron Age (from 9000 to 500 BCE). The researchers performed both morphological and paleogenetic analyses, scrutinizing mitochondrial DNA, Y chromosome DNA, and DNA markers related to coat color. They found that nonlocal genetic lineages still present in domestic horses today suddenly appeared in about 2000 BCE rather than developing gradually over time, as would be expected if these changes emerged within Anatolia. This directs attention to nearby Black Sea regions as a more likely origin for domesticated horses, the authors say.

New Viking DNA research yields unexpected information about who they were

In the popular imagination, Vikings were fearsome blonde-haired warriors from Scandinavia who used longboats to carry out raids across Europe in a brief but bloody reign of terror. But the reality is more complex, says SFU Archaeology Prof. Mark Collard.

Collard is a member of an international team of researchers that has just published the results of the world's largest DNA sequencing of Viking skeletons, in this week's edition of Nature.

Led by Prof. Eske Willerslev of the Universities of Cambridge and Copenhagen, the research team extracted and analysed DNA from the remains of 442 men, women and children.

The remains were recovered from archaeological sites in Scandinavia, the U.K., Ireland, Iceland, Greenland, Estonia, Ukraine, Poland and Russia, and mostly date to the Viking Age (ca. 750-1050 AD).

The team's analyses yielded a number of findings. One of the most noteworthy is that contrary to what has often been assumed, Viking identity was not limited to people of Scandinavian ancestry--the team discovered that two skeletons from a Viking burial site in the Orkney Islands were of Scottish ancestry.

They also found evidence that there was significant gene flow into Scandinavia from the British Isles, Southern Europe, and Asia before and during the Viking Age, which further undermines the image of the Vikings as 'pure' Scandinavians.

Another discovery that runs counter to the standard image of the Vikings is that many had brown hair, not blonde hair.

The analyses' results also shed light on the Vikings' activities. For example, consistent with patterns documented by historians and archaeologists, the team found that Vikings who travelled to England generally had Danish ancestry, while the majority of Vikings who travelled to Scotland, Ireland, Iceland and Greenland had Norwegian ancestry. In contrast, Vikings who headed east were mostly from Sweden.

Interestingly, says Collard, data revealed a number of close kin among the 442 individuals. Four members of a Viking raiding party interred in a boat burial in Estonia were found to be brothers, while two individuals buried 300 to 400 kilometers apart in Sweden were found to be cousins. Perhaps even more strikingly, the team identified a pair of second-degree male relatives (i.e. half-brothers, nephew-uncle, or grandson-grandfather) from two sites, one in Denmark and one in England.

"We have this image of well-connected Vikings mixing with each other, trading and going on raiding parties to fight Kings across Europe because this is what we see on television and read in books - but genetically we have shown for the first time that it wasn't that kind of world. This study changes the perception of who a Viking actually was," says Willerslev. "No one could have predicted these significant gene flows into Scandinavia from Southern Europe and Asia happened before and during the Viking Age."

Of all the team's discoveries, Collard is most intrigued by the identification of close kin.

"While the 'big picture' discoveries are great, I was blown away by the fact that the analyses revealed the presence of four brothers in the Estonian boat burial, and a possible nephew and uncle on either side of the North Sea."

"These findings have important implications for social life in the Viking world, but we would've remained ignorant of them without ancient DNA. They really underscore the power of the approach for understanding history."

Tuesday, September 15, 2020

Dust may have controlled ancient human civilization


New study published in Geology


Research News




Boulder, Colo., USA: When early humans began to travel out of Africa and spread into Eurasia over a hundred thousand years ago, a fertile region around the eastern Mediterranean Sea called the Levant served as a critical gateway between northern Africa and Eurasia. A new study, published in Geology, shows that the existence of that oasis depended almost entirely on something we almost never think about: dust.

Dr. Rivka Amit, at the Geological Survey of Israel, and her team initially set out with a simple question: why are some soils around the Mediterranean thin and why are some thick? Their investigation led them to discover not only that dust deposition played a critical role in forming thick soils in the Levant, but also that had the source of dust not changed 200,000 years ago, early humans might have had a much tougher time leaving Africa, and parts of the Fertile Crescent wouldn't have been so hospitable for civilization to take root.

Thick soils tend to form in areas with wet, humid climates, and thin soils form in arid environments with lower weathering rates. But in the Mediterranean, where much of the bedrock is dissolvable carbonate, the opposite is true: wetter northern regions have thin, unproductive soils, and more arid southeastern regions have thick, productive soils. Some scientists have attributed these patterns to differences in the rates of erosion, driven by human activity. But for Amit, who has been studying the area for years, a high erosion rate alone didn't make sense. She challenged the existing hypotheses, reasoning that another factor--dust input--likely plays a critical role when weathering rates are too slow to form soils from bedrock.

To assess the influence of dust on Mediterranean soils, Amit and her team needed to trace the dust back to its original source. They collected dust samples from soils in the region, as well as nearby and far-flung dust sources, and compared the samples' grain size distribution. The team identified a key difference between areas with thin and thick soils: thin soils comprised only the finest grain sizes sourced from distant deserts like the Sahara, whereas the thicker, more productive soils had coarser dust called loess, sourced from the nearby Negev desert and its massive dune fields. The thick soils in the eastern Mediterranean formed 200,000 years ago when glaciers covered large swaths of land, grinding up bedrock and creating an abundance of fine-grained sediments. "The whole planet was a lot dustier," Amit said, which allowed extensive dune fields like those in the Negev to build up, creating new sources of dust and ultimately, thicker soils in places like the Levant.

Amit, then, had her answer: regions with thin soils simply hadn't received enough loess to form thick, agriculturally productive soils, whereas the southeastern Mediterranean had. "Erosion here is less important," she said. "What's important is whether you get an influx of coarse [dust] fractions. [Without that], you get thin, unproductive soils."

Amit didn't stop there. She now knew that the thickest soils had received a large flux of coarse dust, leading to the area's designation as the "land of milk and honey" for its agricultural productivity. Her next question was, had it always been like this?

She was surprised at what they found. Looking below the loess in the soil profile, they found a dearth of fine-grained sediments. "What was [deposited] before the loess were very thin soils," she said. "It was a big surprise... The landscape was totally different, so I'm not sure that people would [have chosen] this area to live in because it was a harsh environment and [an] almost bare landscape, without much soil." Without the changing winds and formation of the Negev dune field, then, the fertile area that served as a passage for early humans may have been too difficult to pass through and survive.

In the modern Mediterranean, the soils aren't accumulating any more. "The dust source is cut off," Amit explained, since the glaciers retreated in the Holocene, "now we're only reworking the old loess." Even if there were a dust source, it would take tens of thousands of years to rebuild a soil there. That leaves these mountainous soils in a fragile state, and people living there must balance conservation and agricultural use. Employing responsible agricultural practices in the region, as terracing has been used for thousands of years, is critical for soil preservation if agriculture is to continue.