̽��ֱ�� of Cambridge - Robert Foley

Mapping the family tree of stars

ps748 — Mon, 20 Feb 2017 12:31:37 +0000

By studying chemical signatures found in the stars, they are piecing together these evolutionary trees looking at how the stars formed and how they are connected to each other. ̽��ֱ��signatures act as a proxy for DNA sequences. It’s akin to chemical tagging of stars and forms the basis of a discipline astronomers refer to as Galactic archaeology.

It was Charles Darwin, who, in 1859 published his revolutionary theory that all life forms are descended from one common ancestor. This theory has informed evolutionary biology ever since but it was a chance encounter between an astronomer and an biologist over dinner at King’s College in Cambridge that got the astronomer thinking about how it could be applied to stars in the Milky Way.

Writing in Monthly Notices of the Royal Astronomical Society, Dr Paula Jofré, of the ̽��ֱ�� of Cambridge’s Institute of Astronomy, describes how she set about creating a phylogenetic “tree of life” that connects a number of stars in the galaxy.

“ ̽��ֱ��use of algorithms to identify families of stars is a science that is constantly under development. Phylogenetic trees add an extra dimension to our endeavours which is why this approach is so special. ̽��ֱ��branches of the tree serve to inform us about the stars’ shared history“ she says.

̽��ֱ��team picked twenty-two stars, including the Sun, to study. ̽��ֱ��chemical elements have been carefully measured from data coming from ground-based high-resolution spectra taken with large telescopes located in the north of Chile. Once the families were identified using the chemical DNA, their evolution was studied with the help of their ages and kinematical properties obtained from the space mission Hipparcos, the precursor of Gaia, the spacecraft orbiting Earth that was launched by the European Space Agency and is almost halfway through a 5-year project to map the sky.

Stars are born from violent explosions in the gas clouds of the galaxy. Two stars with the same chemical compositions are likely to have been born in the same molecular cloud. Some live longer than the age of the Universe and serve as fossil records of the composition of the gas at the time they were formed. ̽��ֱ��oldest star in the sample analysed by the team is estimated to be almost ten billion years old, which is twice as old as the Sun. ̽��ֱ��youngest is 700 million years old.

In evolution, organisms are linked together by a pattern of descent with modification as they evolve. Stars are very different from living organisms, but they still have a history of shared descent as they are formed from gas clouds, and carry that history in their chemical structure. By applying the same phylogenetic methods that biologists use to trace descent in plants and animals it is possible to explore the ‘evolution’ of stars in the Galaxy.

“ ̽��ֱ��differences between stars and animals is immense, but they share the property of changing over time, and so both can be analysed by building trees of their history”, says Professor Robert Foley, of the Leverhulme Centre for Human Evolutionary Studies at Cambridge.

With an increasing number of datasets being made available from both Gaia and more advanced telescopes on the ground, and on-going and future large spectroscopic surveys, astronomers are moving closer to being able to assemble one tree that would connect all the stars in the Milky Way.

Paula Jofré et al. ‘Cosmic phylogeny: reconstructing the chemical history of the solar neighbourhood with an evolutionary tree’ is published by Monthly Notices of the Royal Astronomical Society. DOI 10.1093/mnras/stx075

Astronomers are borrowing principles applied in biology and archaeology to build a family tree of the stars in the galaxy.

̽��ֱ��branches of the tree serve to inform us about the stars' shared history

Dr Paula Jofré

Institute of Astronomy

Image showing family trees of stars in our Galaxy, including the Sun

̽��ֱ��text in this work is licensed under a Creative Commons Attribution 4.0 International License. For image use please see separate credits above.

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Unprecedented study of Aboriginal Australians points to one shared Out of Africa migration for modern humans

tdk25 — Wed, 21 Sep 2016 18:00:19 +0000

̽��ֱ��first major genomic study of Aboriginal Australians ever undertaken has confirmed that all present-day non-African populations are descended from the same single wave of migrants, who left Africa around 72,000 years ago.

Researchers sequenced the complete genetic information of 83 Aboriginal Australians, as well as 25 Papuans from New Guinea, to produce a host of significant new findings about the origins of modern human populations. Their work is published alongside several other related papers in the journal Nature.

̽��ֱ��study, by an international team of academics, was carried out in close collaboration with elders and leaders from various Aboriginal Australian communities – some of whom are co-authors on the paper – as well as with various other organisations representing the participating groups.

Alongside the prevailing conclusion, that the overwhelming majority of the genomes of non-Africans alive today stem from one ancestral group of migrants who left Africa together, there are several other standout findings. These include:

Compelling evidence that Aboriginal Australians are descended directly from the first people to inhabit Australia – which is still the subject of periodic political dispute.
Evidence of an uncharacterised – and perhaps unknown – early human species which interbred with anatomically modern humans as they migrated through Asia.
Evidence that a mysterious dispersal from the northeastern part of Australia roughly 4,000 years ago contributed to the cultural links between Aboriginal groups today. These internal migrants defined the way in which people spoke and thought, but then disappeared from most of the continent, in a manner which the researchers describe as “ghost-like”.

̽��ֱ��study’s senior authors are from the ̽��ֱ�� of Cambridge, the Wellcome Trust Sanger Institute, the Universities of Copenhagen, Bern and Griffith ̽��ֱ�� Australia. Within Cambridge, members of the Leverhulme Centre for Evolutionary Studies also contributed to the research, in particular by helping to place the genetic data which the team gathered in the field within the context of wider evidence about early human population and migration patterns.

Professor Eske Willerslev, who holds posts at St John’s College, ̽��ֱ�� of Cambridge, the Sanger Institute and the ̽��ֱ�� of Copenhagen, initiated and led the research. He said: “ ̽��ֱ��study addresses a number of fundamental questions about human evolution – how many times did we leave Africa, when was Australia populated, and what is the diversity of people in and outside Australia?”

“Technologically and politically, it has not really been possible to answer those questions until now. We found evidence that there was only really one wave of humans who gave rise to all present-day non-Africans, including Australians.”

Anatomically modern humans are known to have left Africa approximately 72,000 years ago, eventually spreading across Asia and Europe. Outside Africa, Australia has one of the longest histories of continuous human occupation, dating back about 50,000 years.

Some researchers believe that this deep history indicates that Papuans and Australians stemmed from an earlier migration than the ancestors of Eurasian peoples; others that they split from Eurasian progenitors within Africa itself, and left the continent in a separate wave.

Until the present study, however, the only genetic evidence for Aboriginal Australians, which is needed to investigate these theories, came from one tuft of hair (taken from a long-since deceased individual), and two unidentified cell lines.

̽��ֱ��new research dramatically improves that picture. Working closely with community elders, representative organisations and the ethical board of Griffith ̽��ֱ��, Willerslev and colleagues obtained permission to sequence dozens of Aboriginal Australian genomes, using DNA extracted from saliva.

This was compared with existing genetic information about other populations. ̽��ֱ��researchers modelled the likely genetic impact of different human dispersals from Africa and towards Australia, looking for patterns that best matched the data they had acquired. Dr Marta Mirazon Lahr and Professor Robert Foley, both from the Leverhulme Centre, assisted in particular by analysing the likely correspondences between this newly-acquired genetic evidence and a wider framework of existing archaeological and anthropological evidence about early human population movements.

Dr Manjinder Sandhu, a senior author from the Sanger Institute and ̽��ֱ�� of Cambridge, said: “Our results suggest that, rather than having left in a separate wave, most of the genomes of Papuans and Aboriginal Australians can be traced back to a single ‘Out of Africa’ event which led to modern worldwide populations. There may have been other migrations, but the evidence so far points to one exit event.”

̽��ֱ��Papuan and Australian ancestors did, however, diverge early from the rest, around 58,000 years ago. By comparison, European and Asian ancestral groups only become distinct in the genetic record around 42,000 years ago.

̽��ֱ��study then traces the Papuan and Australian groups’ progress. Around 50,000 years ago they reached “Sahul” – a prehistoric supercontinent that originally united New Guinea, Australia and Tasmania, until these regions were separated by rising sea levels approximately 10,000 years ago.

̽��ֱ��researchers charted several further “divergences” in which various parts of the population broke off and became genetically isolated from others. Interestingly, Papuans and Aboriginal Australians appear to have diverged about 37,000 years ago – long before they became physically separated by water. ̽��ֱ��cause is unclear, but one reason may be the early flooding of the Carpentaria basin, which left Australia connected to New Guinea by a strip of land that may have been unfavourable for human habitation.

Once in Australia, the ancestors of today’s Aboriginal communities remained almost completely isolated from the rest of the world’s population until just a few thousand years ago, when they came into contact with some Asian populations, followed by European travellers in the 18th Century.

Indeed, by 31,000 years ago, most Aboriginal communities were genetically isolated from each other. This divergence was most likely caused by environmental barriers; in particular the evolution of an almost impassable central desert as the Australian continent dried out.

Assistant Professor Anna-Sapfo Malaspinas, from the Universities of Copenhagen and Bern, and a lead author, said: “ ̽��ֱ��genetic diversity among Aboriginal Australians is amazing. Because the continent has been populated for such a long time, we find that groups from south-western Australia are genetically more different from north-eastern Australia, than, for example, Native Americans are from Siberians.”

Two other major findings also emerged. First, the researchers were able to reappraise traces of DNA which come from an ancient, extinct human species and are found in Aboriginal Australians. These have traditionally been attributed to encounters with Denisovans – a group known from DNA samples found in Siberia.

In fact, the new study suggests that they were from a different, as-yet uncharacterised, species. “We don’t know who these people were, but they were a distant relative of Denisovans, and the Papuan/Australian ancestors probably encountered them close to Sahul,” Willerslev said.

Finally, the research also offers an intriguing new perspective on how Aboriginal culture itself developed, raising the possibility of a mysterious, internal migration 4,000 years ago.

About 90% of Aboriginal communities today speak languages belonging to the “Pama-Nyungan” linguistic family. ̽��ֱ��study finds that all of these people are descendants of the founding population which diverged from the Papuans 37,000 years ago, then diverged further into genetically isolated communities.

This, however, throws up a long-established paradox. Language experts are adamant that Pama-Nyungan languages are much younger, dating back 4,000 years, and coinciding with the appearance of new stone technologies in the archaeological record.

Scientists have long puzzled over how – if these communities were completely isolated from each other and the rest of the world – they ended up sharing a language family that is much younger? ̽��ֱ��traditional answer has been that there was a second migration into Australia 4,000 years ago, by people speaking this language.

But the new research finds no evidence of this. Instead, the team uncovered signs of a tiny gene flow, indicating a small population movement from north-east Australia across the continent, potentially at the time the Pama-Nyungan language and new stone tool technologies appeared.

These intrepid travellers, who must have braved forbidding environmental barriers, were small in number, but had a significant, sweeping impact on the continent’s culture. Mysteriously, however, the genetic evidence for them then disappears. In short, their influential language and culture survived – but they, as a distinctive group, did not.

“It’s a really weird scenario,” Willerslev said. “A few immigrants appear in different villages and communities around Australia. They change the way people speak and think; then they disappear, like ghosts. And people just carry on living in isolation the same way they always have. This may have happened for religious or cultural reasons that we can only speculate about. But in genetic terms, we have never seen anything like it before.”

̽��ֱ��paper, A Genomic History of Aboriginal Australia, is published in Nature. doi:10.1038/nature18299.

Inset images: Professor Eske Willerslev talking to Aboriginal elders in the Kalgoorlie area in southwestern Australia in 2012. (Photo credit: Preben Hjort, Mayday Film). / Map showing main findings from the paper. Credit: St John's College, Cambridge.

̽��ֱ��first significant investigation into the genomics of Aboriginal Australians has uncovered several major findings about early human populations. These include evidence of a single “Out of Africa” migration event, and of a previously unidentified, “ghost-like” population spread which provided a basis for the modern Aboriginal cultural landscape.

We found evidence that there was only really one wave of humans who gave rise to all present-day non-Africans, including Australians

Eske Willerslev

Preben Hjort, Magus Film

Aubrey Lynch, elder from the Wongatha Aboriginal language group, who participated in the study.

̽��ֱ��text in this work is licensed under a Creative Commons Attribution 4.0 International License. For image use please see separate credits above.

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Opinion: No giant leap for mankind: why we’ve been looking at human evolution in the wrong way

Anonymous — Tue, 14 Jun 2016 13:21:45 +0000

Understanding exactly how and why humans evolved is clearly one of the most important goals in science. But despite a significant amount of research to date, these questions have remained a bit of a mystery. Of course, there is no shortage of theories – it has even been suggested that humans are just visiting aliens. However, most of the credible models tend to take something that is unique to humans – such as language – and show how all the other bits of being human derive from that.

But focusing on one dramatic change as an evolutionary driver in this way may not be the best approach to understanding our past. ̽��ֱ��question was discussed in a series of papers in Philosophical Transactions of the Royal Society B.

Hunting is a good example, as it is often used to explain human evolution. We eat far more meat than other primates – most of them are in fact entirely vegetarian. It has therefore been argued that meat was the high quality resource that allowed humans to evolve large and complex brains.

What’s more, it takes communication, cooperation and technology (those stone tools came in handy) to acquire it, so hunting could also explain a number of other typically human traits. Eating large animals also could also taught humans to share, leading to social cohesion and interdependence. Hunting is just one of many models that have been proposed to explain human uniqueness and cultural complexity – language, fire, cooking and grandmothers, who enhanced human success by investing in their daughters children instead of having more themselves.

Vince Smith/Flickr, CC BY-SA

̽��ֱ��problem with these theories is that they depend on evolution being a sort of one-step game, where one change produces a great leap forward, one from which other changes cascade. But the record does not support this. We split from our last common ancestor with the chimpanzees 5-6m years ago. But when we look at human ancestors between then and now, we do not find a single moment of dramatic change. Instead, it was cumulative – some 4m years ago we started walking upright on two legs, and about a million years later we started using stone tools. ̽��ֱ��size of our brains only started enlarging about 2m years ago.

Certainly there were periods that involved a more dynamic series of changes than others. For example, there was one at the beginning based on how hominins moved across the landscape, becoming bipedal and ranging over larger areas. Then about 2-3m years ago, there was another period of changes when brain size started to increase and childhood and adolescence periods started getting longer. This was coupled with boosts in technology and resource acquisition, such as hunting and gathering.

A final such period occurred in the last half million years, when cognitive changes associated with language, cooperation and cumulative culture – such as the development of more complex and composite technology, and the use of material culture for symbolic purposes – came to the fore. But even these periods, each lasting hundreds of thousands of years, were multi-event processes.

̽��ֱ��big picture

As far as we can tell, human evolution is like a mosaic of change, made up of many small steps, each of which adds a piece to what it is to be human. Only at the end do we see the full configuration, but had we stopped the clock at any point along that continuum, we would have seen a different mosaic. Human evolution is not one great transition, therefore, but many smaller ones.

Part of the problem in trying to see the big pattern of human evolution is that we look at it through the lens of the present – how we are today is the guide to how we were in the past. But the past was different in so many ways, and our extinct relatives show some surprising departures from what we expect when we base those expectations on ourselves.

̽��ֱ��remains of a Neanderthal wikimedia, CC BY-SA

Take body size. In the developed world, we are big, and sadly getting bigger in unhealthy ways. Better nutrition has led to increased body mass in many populations across the world. We also associate being large with being human, as it was thought that our ultimate ancestors, the australopithecines (living in Africa between about 4m and 2m years ago) were small, and that our own genus, Homo, marked a substantial increase in body size.

But that may not have been the case. In fact, nearly all the early, extinct species and subspecies of Homo were small, if not very small. ̽��ֱ��global average human body weight (combined sexes) now is over 60kg. No fossil hominin until the Neanderthals and modern humans reached an average of 50 kg, and most were below 40 kg – half the size of the average American male. Pygmy populations in Africa and Asia also weigh about 40kg, which means that most early and extinct hominins were pygmy sized. There are many advantages to large body size – such as resisting predators, access to larger prey – and the fact that our earliest ancestors did not become large tells us a lot about the energetic constraints under which they lived and reproduced.

We may picture our ancestors as rugged versions of ourselves, tall and strong, but they were not. We need to start thinking of them as creatures that were as unique as ourselves, but in different ways.

Understanding more about human evolution will depend on finding more fossils and applying more and more powerful scientific techniques. Ancient DNA, for example, is revealing extraordinary new details about our recent past. As important, however, will be using our greater knowledge of the overall pattern of human evolution, its tempo and mode, to inform us about the cumulative processes by which we became human, rather than expecting that with one great evolutionary bound, our hero was free.

Robert Foley, Professor of Human Evolution, ̽��ֱ�� of Cambridge

This article was originally published on ̽��ֱ��Conversation. Read the original article.

̽��ֱ��opinions expressed in this article are those of the individual author(s) and do not represent the views of the ̽��ֱ�� of Cambridge.

Robert Foley (Department of Archaeology and Anthropology) discusses the cumulative processes by which we became human.

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Australopithecus afarensis reconstruction

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Evidence of a prehistoric massacre extends the history of warfare

fpjl2 — Wed, 20 Jan 2016 17:35:21 +0000

̽��ֱ��fossilised bones of a group of prehistoric hunter-gatherers who were massacred around 10,000 years ago have been unearthed 30km west of Lake Turkana, Kenya, at a place called Nataruk.

Researchers from Cambridge ̽��ֱ��’s Leverhulme Centre for Human Evolutionary Studies (LCHES) found the partial remains of 27 individuals, including at least eight women and six children.

Twelve skeletons were in a relatively complete state, and ten of these showed clear signs of a violent death: including extreme blunt-force trauma to crania and cheekbones, broken hands, knees and ribs, arrow lesions to the neck, and stone projectile tips lodged in the skull and thorax of two men.

Several of the skeletons were found face down; most had severe cranial fractures. Among the in situ skeletons, at least five showed “sharp-force trauma”, some suggestive of arrow wounds. Four were discovered in a position indicating their hands had probably been bound, including a woman in the last stages of pregnancy. Foetal bones were uncovered.

̽��ֱ��bodies were not buried. Some had fallen into a lagoon that has long since dried; the bones preserved in sediment.

̽��ֱ��findings suggest these hunter-gatherers, perhaps members of an extended family, were attacked and killed by a rival group of prehistoric foragers. Researchers believe it is the earliest scientifically-dated historical evidence of human conflict – an ancient precursor to what we call warfare.

̽��ֱ��origins of warfare are controversial: whether the capacity for organised violence occurs deep in the evolutionary history of our species, or is a symptom of the idea of ownership that came with the settling of land and agriculture.

̽��ֱ��Nataruk massacre is the earliest record of inter-group violence among prehistoric hunter-gatherers who were largely nomadic. ̽��ֱ��only comparable evidence, discovered in Sudan in the 1960s, is undated, although often quoted as of similar age. It consists of cemetery burials, suggesting a settled lifestyle.

“ ̽��ֱ��deaths at Nataruk are testimony to the antiquity of inter-group violence and war,” said Dr Marta Mirazón Lahr, from Cambridge’s LCHES, who directs the ERC-funded IN-AFRICA Project and led the Nataruk study, published today in the journal Nature.

“These human remains record the intentional killing of a small band of foragers with no deliberate burial, and provide unique evidence that warfare was part of the repertoire of inter-group relations among some prehistoric hunter-gatherers,” she said.

̽��ֱ��site was first discovered in 2012. Following careful excavation, the researchers used radiocarbon and other dating techniques on the skeletons – as well as on samples of shell and sediment surrounding the remains – to place Nataruk in time. They estimate the event occurred between 9,500 to 10,500 years ago, around the start of the Holocene: the geological epoch that followed the last Ice Age.

Now scrubland, 10,000 years ago the area around Nataruk was a fertile lakeshore sustaining a substantial population of hunter-gatherers. ̽��ֱ��site would have been the edge of a lagoon near the shores of a much larger Lake Turkana, likely covered in marshland and bordered by forest and wooded corridors.

This lagoon-side location may have been an ideal place for prehistoric foragers to inhabit, with easy access to drinking water and fishing – and consequently, perhaps, a location coveted by others. ̽��ֱ��presence of pottery suggests the storage of foraged food.

“ ̽��ֱ��Nataruk massacre may have resulted from an attempt to seize resources – territory, women, children, food stored in pots – whose value was similar to those of later food-producing agricultural societies, among whom violent attacks on settlements became part of life,” said Mirazón Lahr.

“This would extend the history of the same underlying socio-economic conditions that characterise other instances of early warfare: a more settled, materially richer way of life. However, Nataruk may simply be evidence of a standard antagonistic response to an encounter between two social groups at that time.”

Click on images to enlarge

Antagonism between hunter-gatherer groups in recent history often resulted in men being killed, with women and children subsumed into the victorious group. At Nataruk, however, it seems few, if any, were spared.

Of the 27 individuals recorded, 21 were adults: eight males, eight females, and five unknown. Partial remains of six children were found co-mingled or in close proximity to the remains of four adult women and of two fragmentary adults of unknown sex.

No children were found near or with any of the men. All except one of the juvenile remains are children under the age of six; the exception is a young teenager, aged 12-15 years dentally, but whose bones are noticeably small for his or her age.

Ten skeletons show evidence of major lesions likely to have been immediately lethal. As well as five – possibly six – cases of trauma associated with arrow wounds, five cases of extreme blunt-force to the head can be seen, possibly caused by a wooden club. Other recorded traumas include fractured knees, hands and ribs.

Three artefacts were found within two of the bodies, likely the remains of arrow or spear tips. Two of these are made from obsidian: a black volcanic rock easily worked to razor-like sharpness. “Obsidian is rare in other late Stone Age sites of this area in West Turkana, which may suggest that the two groups confronted at Nataruk had different home ranges,” said Mirazón Lahr.

One adult male skeleton had an obsidian ‘bladelet’ still embedded in his skull. It didn’t perforate the bone, but another lesion suggests a second weapon did, crushing the entire right-front part of the head and face. “ ̽��ֱ��man appears to have been hit in the head by at least two projectiles and in the knees by a blunt instrument, falling face down into the lagoon’s shallow water,” said Mirazón Lahr.

Another adult male took two blows to the head – one above the right eye, the other on the left side of the skull – both crushing his skull at the point of impact, causing it to crack in different directions.

̽��ֱ��remains of a six-to-nine month-old foetus were recovered from within the abdominal cavity of one of the women, who was discovered in an unusual sitting position – her broken knees protruding from the earth were all Mirazón Lahr and colleagues could see when they found her. ̽��ֱ��position of the body suggests that her hands and feet may have been bound.

The Nataruk remains are now housed at the Turkana Basin Institute, Turkwell Station, for the National Museums of Kenya.

While we will never know why these people were so violently killed, Nataruk is one of the clearest cases of inter-group violence among prehistoric hunter-gatherers, says Mirazón Lahr, and evidence for the presence of small-scale warfare among foraging societies.

For study co-author Professor Robert Foley, also from Cambridge’s LCHES, the findings at Nataruk are an echo of human violence as ancient, perhaps, as the altruism that has led us to be the most cooperative species on the planet.

“I’ve no doubt it is in our biology to be aggressive and lethal, just as it is to be deeply caring and loving. A lot of what we understand about human evolutionary biology suggests these are two sides of the same coin,” Foley said.

Skeletal remains of a group of foragers massacred around 10,000 years ago on the shores of a lagoon is unique evidence of a violent encounter between clashing groups of ancient hunter-gatherers, and suggests the “presence of warfare” in late Stone Age foraging societies.

̽��ֱ��deaths at Nataruk are testimony to the antiquity of inter-group violence and war

Marta Mirazón Lahr

Left: Skull of a man found lying prone in the lagoons sediments. ̽��ֱ��skull has multiple lesions consistent with wounds from a blunt implement. Right: ̽��ֱ��skull in situ.

̽��ֱ��text in this work is licensed under a Creative Commons Attribution 4.0 International License. For image use please see separate credits above.

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Opinion: Finding a hunter-gatherer massacre scene that may change history of human warfare

Anonymous — Tue, 19 Jan 2016 13:09:24 +0000

̽��ֱ��area surrounding Lake Turkana in Kenya was lush and fertile 10,000 years ago, with thousands of animals – including elephants, giraffes and zebras – roaming around alongside groups of hunter gatherers. But it also had a dark side. We have discovered the oldest known case of violence between two groups of hunter gatherers took place there, with ten excavated skeletons showing evidence of having been killed with both sharp and blunt weapons.

̽��ֱ��findings, published in Nature, are important because they challenge our understanding of the roots of conflict and suggest warfare may have a much older history than many researchers believe.

Shocking finding

Our journey started in 2012, when Pedro Ebeya, one of our Turkana field assistants, reported seeing fragments of human bones on the surface at Nataruk. Located just south of Lake Turkana, Nataruk is today a barren desert, but 10,000 years ago was a temporary camp set up by a band of hunter-gatherers next to a lagoon. I led a team of researchers, as part of the In-Africa project, which has been working in the area since 2009. We excavated the remains of 27 people – six young children, one teenager and 20 adults. Twelve of these – both men and women – were found as they had died, unburied, and later covered by the shallow water of the lagoon.

Ten of the 12 skeletons show lesions caused by violence to the parts of the body most commonly involved in cases of violence. These include one where the projectile was still embedded in the side of the skull; two cases of sharp-force trauma to the neck; seven cases of blunt and/or sharp-force trauma to the head; two cases of blunt-force trauma to the knees and one to the ribs. There were also two cases of fractures to the hands, possibly caused while parrying a blow.

There must have at least three types of weapons involved in these murders – projectiles (stoned-tipped as well as sharpened arrows), something similar to a club, and something close to a wooden handle with hafted sharp-stone blades that caused deep cuts. Two individuals have no lesions in the preserved parts of the skeleton, but the position of their hands suggests they may have been bound, including a young woman who was heavily pregnant at the time.

Me and my colleague, Justus Edung, during the excavations. Credit: Robert Foley

We dated the remains and the site to between 10,500 and 9,500 years ago, making them the earliest scientifically dated case of a conflict between two groups of hunter-gatherers. Stones in the weapons include obsidian, a rare stone in the Nataruk area, suggesting the attackers came from a different place.

̽��ֱ��(pre)history of warfare

Today we think of warfare, or inter-group conflict, as something that happens when one group of people wants the territory, resources or power held by another. But prehistoric societies were usually small groups of nomads moving from place to place – meaning they didn’t own land or have significant possessions. They typically didn’t have strong social hierarchies either. Therefore, many scholars have argued that warfare must have emerged after farming and more complex political systems arose.

Man with an obsidian bladelet embedded into the left side of his skull, and a projectile lesion (possibly of a sharpened arrow shaft) on the right side of the skull. Marta Mirazon Lahr

Naturuk therefore challenges our views about what the causes of conflict are. It is possible that human prehistoric societies simply responded antagonistically to chance encounters with another group. But this is not what seems to have happened at Nataruk. ̽��ֱ��group which attacked was carrying weapons that would not normally be carried while hunting and fishing. In addition, the lesions show that clubs of at least two sizes were used, making it likely that more than one of the attackers were carrying them.

̽��ֱ��fact that the attack combined long-distance weapons such as arrows and close-proximity weaponry such as clubs suggests they planned the attack. Also, there are other, but isolated, examples of violent trauma in this area from this period in time – one discovered in the 1970s about 20km north of Nataruk, and two discovered by our project at a nearby site. All three involved projectiles, one of the hallmarks of inter-group conflict. Two of the projectiles found embedded in the bones at Nataruk and in two of the other cases were made of obsidian. This tells us that such attacks happened multiple times, and were part of the life of the hunter-gatherer communities at the time.

So why were the people of Nataruk attacked? We have to conclude that they had valuable resources that were worth fighting for – water, meat, fish, nuts, or indeed women and children. This suggests that two of the conditions associated with warfare among settled societies – territory and resources – were probably common among these hunter-gatherers, and that we have underestimated their role so far.

Evolution is about survival, and our species is no different from others in this respect. ̽��ֱ��injuries suffered by the people of Nataruk are merciless and shocking, but no different from those suffered in wars throughout much of our history – sadly even today. It may be human nature, but we should not forget that extraordinary acts of altruism, compassion and caring are also unique parts of who we are.

Marta Mirazon Lahr, Reader in Human Evolutionary Biology & Director of the Duckworth Collection, ̽��ֱ�� of Cambridge

This article was originally published on ̽��ֱ��Conversation. Read the original article.

̽��ֱ��opinions expressed in this article are those of the individual author(s) and do not represent the views of the ̽��ֱ�� of Cambridge.

Marta Mirazon Lahr (Leverhulme Centre for Human Evolutionary Studies) discusses the discovery, made by her and her team, of the oldest known case of violence between two groups of hunter gatherers.

Image by Marta Mirazon Lahr, enhanced by Fabio Lahr

Skull of a man with multiple lesions on the side, probably caused by a club.

̽��ֱ��text in this work is licensed under a Creative Commons Attribution 4.0 International License. For image use please see separate credits above.

Yes

Plague in humans ‘twice as old’ but didn’t begin as flea-borne, ancient DNA reveals

fpjl2 — Thu, 22 Oct 2015 16:09:48 +0000

New research using ancient DNA has revealed that plague has been endemic in human populations for more than twice as long as previously thought.

̽��ֱ��study suggests that ancestral plague would have been spread by human-to-human contact – until genetic mutations allowed Yersinia pestis (Y. pestis), the bacterium that causes plague, to survive in the gut of fleas.

These mutations, which may have occurred near the turn of the 1st millennium BC, gave rise to the bubonic form of plague that spreads at terrifying speed through flea – and consequently rat – carriers. ̽��ֱ��bubonic plague caused the pandemics that decimated global populations, including the Black Death, which wiped out half the population of Europe in the 14th century.

Before its flea-borne evolution, however, researchers say that plague was in fact endemic in the human populations of Eurasia at least 3,000 years before the first plague pandemic in historical records (the Plague of Justinian in 541 AD).

They say the new evidence that Y. pestis bacterial infection in humans actually emerged around the beginning of the Bronze Age suggests that plague may have been responsible for major population declines believed to have occurred in the late 4th and early 3rd millennium BC.

̽��ֱ��work was conducted by an international team including researchers from the universities of Copenhagen, Denmark, and Cambridge, UK, and the findings are published today in the journal Cell.

“We found that the Y. pestis lineage originated and was widespread much earlier than previously thought, and we narrowed the time window as to when and how it developed,” said senior author Professor Eske Willerslev, who recently joined Cambridge ̽��ֱ��’s Department of Zoology from the ̽��ֱ�� of Copenhagen.

“ ̽��ֱ��underlying mechanisms that facilitated the evolution of Y. pestis are present even today. Learning from the past may help us understand how future pathogens may arise and evolve,” he said.

Researchers analysed ancient genomes extracted from the teeth of 101 adults dating from the Bronze Age and found across the Eurasian landmass.

They found Y. pestis bacteria in the DNA of seven of the adults, the oldest of whom died 5,783 years ago – the earliest evidence of plague. Previously, direct molecular evidence for Y. pestis had not been obtained from skeletal material older than 1,500 years.

However, six of the seven plague samples were missing two key genetic components found in most modern strains of plague: a “virulence gene” called ymt, and a mutation in an “activator gene” called pla.

̽��ֱ��ymt gene protects the bacteria from being destroyed by the toxins in flea guts, so that it multiplies, choking the flea’s digestive tract. This causes the starving flea to frantically bite anything it can, and, in doing so, spread the plague.

̽��ֱ��mutation in the pla gene allows Y. pestis bacteria to spread across different tissues, turning the localised lung infection of pneumonic plague into one of the blood and lymph nodes.

Researchers concluded these early strains of plague could not have been carried by fleas without ymt. Nor could they cause bubonic plague – which affects the lymphatic immune system, and inflicts the infamous swollen buboes of the Black Death – without the pla mutation.

Consequently, the plague that stalked populations for much of the Bronze Age must have been pneumonic, which directly affects the respiratory system and causes desperate, hacking coughing fits just before death. Breathing around infected people leads to inhalation of the bacteria, the crux of its human-to-human transmission.

Study co-author Dr Marta Mirazón-Lahr, from Cambridge’s Leverhulme Centre for Human Evolutionary Studies (LCHES), points out that a study earlier this year from Willerslev’s Copenhagen group showed the Bronze Age to be a highly active migratory period, which could have led to the spread of pneumonic plague.

“ ̽��ֱ��Bronze Age was a period of major metal weapon production, and it is thought increased warfare, which is compatible with emerging evidence of large population movements at the time. If pneumonic plague was carried as part of these migrations, it would have had devastating effects on small groups they encountered,” she said.

“Well-documented cases have shown the pneumonic plague’s chain of infection can go from a single hunter or herder to ravaging an entire community in two to three days.”

̽��ֱ��most recent of the seven ancient genomes to reveal Y. pestis in the new study has both of the key genetic mutations, indicating an approximate timeline for the evolution that spawned flea-borne bubonic plague.

“Among our samples, the mutated plague strain is first observed in Armenia in 951 BC, yet is absent in the next most recent sample from 1686 BC – suggesting bubonic strains evolve and become fixed in the late 2nd and very early 1st millennium BC,” said Mirazón-Lahr.

“However, the 1686 BC sample is from the Altai mountains near Mongolia. Given the distance between Armenia and Altai, it’s also possible that the Armenian strain of bubonic plague has a longer history in the Middle East, and that historical movements during the 1st millennium BC exported it elsewhere.”

̽��ֱ��Books of Samuel in the Bible describe an outbreak of plague among the Philistines in 1320 BC, complete with swellings in the groin, which the World Health Organization has argued fits the description of bubonic plague. Mirazón-Lahr suggests this may support the idea of a Middle Eastern origin for the plague’s highly lethal genetic evolution.

Co-author Professor Robert Foley, also from Cambridge’s LCHES, suggests that the lethality of bubonic plague may have required the right population demography before it could thrive.

“Every pathogen has a balance to maintain. If it kills a host before it can spread, it too reaches a ‘dead end’. Highly lethal diseases require certain demographic intensity to sustain them.

“ ̽��ֱ��endemic nature of pneumonic plague was perhaps more adapted for an earlier Bronze Age population. Then, as Eurasian societies grew in complexity and trading routes continued to open up, maybe the conditions started to favour the more lethal form of plague,” Foley said.

“ ̽��ֱ��Bronze Age is the edge of history, and ancient DNA is making what happened at this critical time more visible,” he said.

Willerslev added: “These results show that the ancient DNA has the potential not only to map our history and prehistory, but also discover how disease may have shaped it.”

Inset image: Map showing where the remains of the Bronze Age plague victims were found.

New research dates plague back to the early Bronze Age, showing it had been endemic in humans across Eurasia for millennia prior to the first recorded global outbreak, and that ancestral plague mutated into its bubonic, flea-borne form between the 2nd and 1st millennium BC.

These results show that the ancient DNA has the potential not only to map our history and prehistory, but also discover how disease may have shaped it

Eske Willerslev

Left: Natalia Shishlina. Right: Centres for Disease Control and Prevention

Left: Skull of a Yamnaya, the people who migrated to Central Asia in early Bronze Age and developed the Afanasievo culture. ̽��ֱ��Afanasievo are one of the Bronze Age groups carrying Y. pestis. Right: Scanning Electron Micrograph Of A Flea

̽��ֱ��text in this work is licensed under a Creative Commons Attribution 4.0 International License. For image use please see separate credits above.

Yes

Saharan 'carpet of tools' is the earliest known man-made landscape

fpjl2 — Wed, 11 Mar 2015 16:29:13 +0000

A new intensive survey of the Messak Settafet escarpment, a massive outcrop of sandstone in the middle of the Saharan desert, has shown that stone tools occur “ubiquitously” across the entire landscape: averaging 75 artefacts per square metre, or 75 million per square kilometre.

Researchers say the vast ‘carpet’ of stone-age tools – extracted from and discarded onto the escarpment over hundreds of thousands of years – is the earliest known example of an entire landscape being modified by hominins: the group of creatures that include us and our ancestral species.

̽��ֱ��Messak Settafet runs a total length of 350 km, with an average width of 60 km. Parts of the landscape are ‘anthropogenic’, or man-made, through build-up of tools over hundreds of thousands of years.

̽��ֱ��research team have used this and other studies to attempt to estimate the volume of stone tools discarded over the last one million years of human evolution on the African continent alone. They say that it is the equivalent of more than one Great Pyramid of Giza per square kilometre of the entire continent (2.1 x 10¹⁴ cubic metres of rock).

“ ̽��ֱ��Messak sandstone, now in the middle of the vast sand seas of Libya, would have been a high quality rock for hominins to fracture – the landscape is in effect a carpet of stone tools, most probably made in the Middle and Upper Pleistocene,” said Professor Robert Foley, from the Leverhulme Centre for Evolutionary Studies at the ̽��ֱ�� of Cambridge, who conducted the research with colleague Dr Marta Mirazón Lahr.

“ ̽��ֱ��term ‘anthropocene’ is now used to denote the point at which humans began to have a significant effect on the environment,” said Mirazón Lahr. “ ̽��ֱ��critical time may well be the beginning of the industrial revolution about 200 years ago. Some talk of an ‘early anthropocene’ about 10,000 years ago when forests began being cleared for agriculture.

“Making stone tools, however, dates back more than two million years, and little research has been done on the impact of this activity. ̽��ֱ��Messak Settafet is the earliest demonstrated example of the scars of human activity across an entire landscape; the effects of our technology on the environment may be considerably older than previously thought,” Mirazón Lahr said. ̽��ֱ��study is published today in the journal PLOS One.

̽��ֱ��survey, conducted in 2011, involved randomly selecting plots of one metre squared across the parts of the plateau surface. In each square, the researchers sifted through all the stones to identify the number that showed evidence of modification through hominin activity – evidence such as a ‘bulb of percussion’: a bulge or curved dent on the surface of a stone tool produced by the angular blows of hominin percussion. ̽��ֱ��average number of artefacts across all sample squares was 75.

At the simple end, large flakes of stone would have been opportunistically hacked from boulders to be used for cutting or as weapons. At the more sophisticated level, researchers found evidence that specific tools had been used to wedge into the stone in order split it.

“It is clear from the scale of activity how important stone tools were, and shows that African hominins were strongly technologically dependent,” said Foley. “Landscapes such as these must have been magnets for hominin populations, either for ‘stone foraging trips’ or residential occupation.”

̽��ֱ��researchers say that if – as seems likely – the success of Stone Age communities depended significantly on tool technology, there would be enormous advantage to knowing, remembering and indeed controlling access to areas with a “super-abundance” of raw materials, such as the Messak Settafet.

“Hominins may well have become tethered to these areas, unable to stray too far if survival depended on access to the raw materials for tools, and forced to make other adaptations subservient to that need,” said Mirazón Lahr.

One way that the environmental impact of hominin tool excavation may have been positive for later humans is through the clusters of small quarrying pits dotted across the landscape (ranging up to 2 metres in diameter, and 50 centimetres in depth).

These pits would have retained moisture – with surface water still visible today after rains – and the small pools would have attracted game. In many of these pits, the team found ‘trapping stones’: large stones used for traps and ties for game and/or cattle during the last 10,000 years.

By combining their data with previous extensive surveys carried out across Africa, the researchers attempted to estimate roughly how much stone had been used as tools and discarded during human evolution.

Although stone tool manufacture dates back at least 2.5 million years, the researchers limited the estimate to one million years. Based on their and others research, they standardised population density (based on extant hunter-gatherers), tool volume, the number of tools used by one person in a year and the amount of resulting debris per tool.

They estimate an average density of between 0.5 and 5 million stone artefacts per square kilometre of Africa. When converted into an estimate of volume, this is the equivalent of between 42 to 84 million Great Pyramids of Giza.

Researchers say this would be the equivalent of finding between 1.3 and 2.7 Great Pyramids per square kilometre throughout Africa.

Researchers used the new survey of the Messak Settafet to estimate that enough stone tools were discarded over the course of human evolution in Africa to build more than one Great Pyramid for every square kilometre of land on the continent.

Landscapes such as these must have been magnets for hominin populations, either for ‘stone foraging trips’ or residential occupation

Robert Foley

Robert Foley/Marta Mirazón Lahr

Left: A view across a valley in the Messak landscape. Right: A Levallois core, a distinctive type of Middle Stone Age stone tool, recovered on the surface of the Messak

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Yes

Ancient DNA shows earliest European genomes weathered the ice age, and shines new light on Neanderthal interbreeding and a mystery human lineage

fpjl2 — Thu, 06 Nov 2014 19:07:25 +0000

A ground-breaking new study on DNA recovered from a fossil of one of the earliest known Europeans - a man who lived 36,000 years ago in Kostenki, western Russia - has shown that the earliest European humans’ genetic ancestry survived the Last Glacial Maximum: the peak point of the last ice age.

̽��ֱ��study also uncovers a more accurate timescale for when humans and Neanderthals interbred, and finds evidence for an early contact between the European hunter-gatherers and those in the Middle East – who would later develop agriculture and disperse into Europe about 8,000 years ago, transforming the European gene pool.

Scientists now believe Eurasians separated into at least three populations earlier than 36,000 years ago: Western Eurasians, East Asians and a mystery third lineage, all of whose descendants would develop the unique features of most non-African peoples - but not before some interbreeding with Neanderthals took place.

Led by the Centre for GeoGenetics at the ̽��ֱ�� of Copenhagen, the study was conducted by an international team of researchers from institutions including the ̽��ֱ�� of Cambridge’s Departments of Archaeology and Anthropology, and Zoology, and is published today in the journal Science.

By cross-referencing the ancient man’s complete genome – the second oldest modern human genome ever sequenced – with previous research, the team discovered a surprising genetic “unity” running from the first modern humans in Europe, suggesting that a ‘meta-population’ of Palaeolithic hunter-gatherers with deep shared ancestry managed to survive through the Last Glacial Maximum and colonise the landmass of Europe for more than 30,000 years.

While the communities within this overarching population expanded, mixed and fragmented during seismic cultural shifts and ferocious climate change, this was a “reshuffling of the same genetic deck” say scientists, and European populations as a whole maintained the same genetic thread from their earliest establishment out of Africa until Middle Eastern populations arrived in the last 8,000 years, bringing with them agriculture and lighter skin colour.

“That there was continuity from the earliest Upper Palaeolithic to the Mesolithic, across a major glaciation, is a great insight into the evolutionary processes underlying human success,” said co-author Dr Marta Mirazón Lahr, from Cambridge’s Leverhulme Centre for Human Evolutionary Studies (LCHES).

“For 30,000 years ice sheets came and went, at one point covering two-thirds of Europe. Old cultures died and new ones emerged - such as the Aurignacian and the Grevettian - over thousands of years, and the hunter-gatherer populations ebbed and flowed. But we now know that no new sets of genes are coming in: these changes in survival and cultural kit are overlaid on the same biological background,” Mirazón Lahr said. “It is only when famers from the Near East arrived about 8,000 years ago that the structure of the European population changed significantly.”

̽��ֱ��Kostenki genome also contained, as with all people of Eurasia today, a small percentage of Neanderthal genes, confirming previous findings which show there was an ‘admixture event’ early in the human colonisation Eurasia: a period when Neanderthals and the first humans to leave Africa for Europe briefly interbred.

̽��ֱ��new study allows scientists to closer estimate this ‘event’ as occurring around 54,000 years ago, before the Eurasian population began to separate. This means that, even today, anyone with a Eurasian ancestry – from Chinese to Scandinavian and North American – has a small element of Neanderthal DNA.

However, despite Western Eurasians going on to share the European landmass with Neanderthals for another 10,000 years, no further periods of interbreeding occurred.

“Were Neanderthal populations dwindling very fast? Did modern humans still encounter them? We were originally surprised to discover there had been interbreeding. Now the question is, why so little? It’s an extraordinary finding that we don’t understand yet,” said co-author Professor Robert Foley, also from LCHES.

Unique to the Kostenki genome is a small element it shares with people who live in parts of the Middle East now, and who were also the population of farmers that arrived in Europe about 8,000 years ago and assimilated with indigenous hunter-gatherers. This early contact is surprising, and provides the first clues to a hereto unknown lineage that could be as old as – or older than – the other major Eurasian genetic lines. These two populations must have interacted briefly before 36,000 years ago, and then remained isolated from each other for tens of millennia.

“This element of the Kostenki genome confirms the presence of a yet unmapped major population lineage in Eurasia. ̽��ֱ��population separated early on from ancestors of other Eurasians, both Europeans and Eastern Asians,” said Andaine Seguin-Orlando from the Centre for GeoGenetics in Copenhagen.

Mirazón Lahr points out that, while Western Eurasia was busy mixing as a ‘meta-population’, there was no interbreeding with these mystery populations for some 30,000 years – meaning there must have been some kind of geographic barrier for millennia, despite the fact that Europe and the Middle East seem, for us at least, to be so close geographically. But the Kostenki genome not only shows the existence of these unmapped populations, but that there was at least one window of time when whatever barrier existed became briefly permeable.

“This mystery population may have remained small for a very long time, surviving in refugia in areas such as the Zagros Mountains of Iran and Iraq, for example,” said Mirazón Lahr. “We have no idea at the moment where they were for those first 30,000 years, only that they were in the Middle East by the end of the ice age, when they invented agriculture.”

Lead author and Lundbeck Foundation Professor Eske Willerslev added: “This work reveals the complex web of population relationships in the past, generating for the first time a firm framework with which to explore how humans responded to climate change, encounters with other populations, and the dynamic landscapes of the ice age.”

Inset images (top-bottom): Russian archeologist Mikhail Mikhaylovich Gerasimov taking the Kostinki skull out of the ground in 1954; the Kostinki skull; Marta Mirazón Lahr and Robert Foley

A genome taken from a 36,000 year old skeleton reveals an early divergence of Eurasians once they had left Africa, and allows scientists to better assess the point at which ‘admixture’ - or interbreeding - between Eurasians and Neanderthals occurred. ̽��ֱ��latest research also points to a previously unknown population lineage as old as the first population separations since humans dispersed out of Africa.

These changes in survival and cultural kit are overlaid on the same biological background

Marta Mirazón Lahr

Peter the Great Museum/Philip Nigst

Kosenki fossil skull, and and illustration of the Kosteni find

Yes