Thursday, May 25, 2017

Ancient DNA evidence shows hunter-gatherers and farmers were intimately linked

In human history, the transition from hunting and gathering to farming is a significant one. As such, hunter-gatherers and farmers are usually thought about as two entirely different sets of people. But researchers reporting new ancient DNA evidence in Current Biology on May 25 show that in the area we now recognize as Romania, at least, hunter-gatherers and farmers were living side by side, intermixing with each other, and having children.

"We expected some level of mixing between farmers and hunter-gatherers, given the archaeological evidence for contact among these communities," says Michael Hofreiter of University of Potsdam in Germany. "However, we were fascinated by the high levels of integration between the two communities as reconstructed from our ancient DNA data."

The findings add evidence to a longstanding debate about how the Neolithic transition, when people gave up hunting and gathering for farming, actually occurred, the researchers say. In those debates, the question has often been about whether the movement of people or the movement of ideas drove the transition.

Earlier evidence suggested that the Neolithic transition in Western Europe occurred mostly through the movement of people, whereas cultural diffusion played a larger role to the east, in Latvia and Ukraine. The researchers in the new study were interested in Romania because it lies between these two areas, presenting some of the most compelling archaeological evidence for contact between incoming farmers and local hunter-gatherers.

Indeed, the new findings show that the relationship between hunter-gatherers and farmers in the Danube basin can be more nuanced and complex. The movement of people and the spread of culture aren't mutually exclusive ideas, the researchers say, "but merely the ends of a continuum."

The researchers came to this conclusion after recovering four ancient human genomes from Romania spanning a time transect between 8.8 thousand and 5.4 thousand years ago. The researchers also analyzed two Mesolithic (hunter-gatherer) genomes from Spain to provide further context.

The DNA revealed that the Romanian genomes from thousands of years ago had significant ancestry from Western hunter-gatherers. However, they also had a lesser but still sizeable contribution from Anatolian farmers, suggesting multiple admixture events between hunter-gatherers and farmers. An analysis of the bones also showed they ate a varied diet, with a combination of terrestrial and aquatic sources.

"Our study shows that such contacts between hunter-gatherers and farmers went beyond the exchange of food and artefacts," Hofreiter says. "As data from different regions accumulate, we see a gradient across Europe, with increasing mixing of hunter-gatherers and farmers as we go east and north. Whilst we still do not know the drivers of this gradient, we can speculate that, as farmers encountered more challenging climatic conditions, they started interacting more with local hunter-gatherers. These increased contacts, which are also evident in the archaeological record, led to genetic mixing, implying a high level of integration between very different people."

The findings are a reminder that the relationships within and among people in different places and at different times aren't simple. It's often said that farmers moved in and outcompeted hunter-gatherers with little interaction between the two. But the truth is surely much richer and more varied than that. In some places, as the new evidence shows, incoming farmers and local hunter-gatherers interacted and mixed to a great extent. They lived together, despite large cultural differences.

Understanding the reasons for why the interactions between these different people led to such varied outcomes, Hofreiter says, is the next big step. The researchers say they now hope to use ancient DNA evidence to add more chapters to the story as they explore the Neolithic transition as it occurred in other parts of the world, outside of Europe.

Wednesday, May 24, 2017

Ochre use by Middle Stone Age humans in Porc-Epic cave persisted over thousands of years

Middle Stone Age humans in the Porc-Epic cave likely used ochre over at least 4,500 years, according to a study published May 24, 2017 in the open-access journal PLOS ONE by Daniela Rosso from the University of Barcelona, Spain, and the University of Bordeaux, France, and colleagues.

Images of ochre, the iron-rich rock characterized by a red or yellow color, that was found at many Middle Stone Age sites.

Rosso et al (2017)

Ochre, an iron-rich rock characterized by a red or yellow color, is found at many Middle Stone Age sites. The largest known East African collection of Middle Stone Age ochre, found at Porc-Epic Cave in Ethiopia, weighs around 40kg and is thought to date to ca. 40,000 years ago. The authors of the present study conducted a detailed analysis of 3792 pieces of ochre, using microscopy and experimental reproduction of grinding techniques to assess how the ochre was processed and used over a 4,500-year timespan.

The researchers found that the cave inhabitants appeared to have persistently acquired, processed, and used the same types of ochre during this period.

Overall the inhabitants of the cave seem to have processed almost half of the ochre pieces, although the proportion of ochre which had been modified decreased progressively over the period. Whilst flaking and scraping of ochre pieces appeared to have become more common over time, the authors noted a reduction in the proportion of pieces which underwent grinding. The gradual nature of shifts in preferred processing techniques may indicate that they resulted from cultural drift within this practice.

Intensively modified ochre pieces show ground facets likely produced with different types of grindstones, at different times. According to the authors, these pieces were probably curated and processed for the production of small amounts of ochre powder. This is consistent with use in symbolic activities, such as the production of patterns or body painting, although a use for utilitarian activities cannot be discarded.

Whilst the increase of ochre use in certain layers could be explained by refining the dating of the sequence and acquiring environmental data, these authors state that their analysis of ochre treatment seems to reflect a "cohesive behavioral system shared by all community members and consistently transmitted through time."

Groundbreaking discovery of early human life in ancient Peru

A-tisket, A-tasket. You can tell a lot from a basket. Especially if it comes from the ruins of an ancient civilization inhabited by humans nearly 15,000 years ago during the Late Pleistocene and Early Holocene ages.

Basket remnants retrieved from the site were made from diverse materials including a local reed that is still used today by modern basket makers. More elaborate baskets included segments made from domesticated cotton and were colored using some of the oldest dyes known in the New World. 
Florida Atlantic University's Harbor Branch Oceanographic Institute

An archeologist from Florida Atlantic University's Harbor Branch Oceanographic Institute is among a team of scientists who made a groundbreaking discovery in Huaca Prieta in coastal Peru - home to one of the earliest and largest pyramids in South America. Hundreds of thousands of artifacts, including intricate and elaborate hand-woven baskets excavated between 2007 and 2013 in Huaca Prieta, reveal that early humans in that region were a lot more advanced than originally thought and had very complex social networks.

For decades, archeologists exploring Peru have argued about the origins and emergence of complex society in Peru. Did it first happen in the highlands with groups who were dependent on agriculture or did it happen along the coast with groups who were dependent on seafood? Evidence from the site indicates a more rapid development of cultural complexity along the Pacific coast than previously thought as published in Science Advances.

"The mounds of artifacts retrieved from Huaca Prieta include food remains, stone tools and other cultural features such as ornate baskets and textiles, which really raise questions about the pace of the development of early humans in that region and their level of knowledge and the technology they used to exploit resources from both the land and the sea," said James M. Adovasio, Ph.D., D.Sc., co-author of the study and a world acclaimed archaeologist at FAU's Harbor Branch, who is the foremost authority on ancient textiles and materials such as those used in basketry.

Among the artifacts excavated are tools used to capture deep-sea fish-like herring. The variety of hooks they used indicate the diversity of fishing that took place at that time and almost certainly the use of boats that could withstand rough waters. These ancient peoples managed to develop a very efficient means of extracting seaside resources and devised complex techniques to collect those resources. They also combined their exploitation of maritime economy with growing crops like chili pepper, squash, avocado and some form of a medicinal plant on land in a way that produced a large economic surplus.

"These strings of events that we have uncovered demonstrate that these people had a remarkable capacity to utilize different types of food resources, which led to a larger society size and everything that goes along with it such as the emergence of bureaucracy and highly organized religion," said Adovasio.

Advosasio's focus of the excavation was on the extensive collection of basket remnants retrieved from the site, which were made from diverse materials including a local reed that is still used today by modern basket makers. More elaborate baskets included segments made from domesticated cotton and were colored using some of the oldest dyes known in the New World.

"To make these complicated textiles and baskets indicates that there was a standardized or organized manufacturing process in place and that all of these artifacts were much fancier than they needed to be for that time period," said Adovasio. "Like so many of the materials that were excavated, even the baskets reflect a level of complexity that signals a more sophisticated society as well as the desire for and a means for showing social stature. All of these things together tell us that these early humans were engaged in very complicated social relationships with each other and that these fancy objects all bespeak that kind of social messaging."

The late archeologist Junius B. Bird was the first to excavate Huaca Prieta in the late 1940s after World War II and his original collection is housed in the American Museum of Natural History in New York. This latest excavation is only the second one to take place at this site, but this time using state-of-the-art archeological technology. This recent excavation took approximately six years to complete and included a total of 32 excavation units and trenches, 32 test pits, and 80 geological cores that were placed on, around and between the Huaca Prieta and Paredones mounds as well as other sites. These artifacts are now housed in a museum in Lima, Peru.

Shared genetic heritage from Sicily to Cyprus

A new genomic study on southern Mediterranean reveals a genetic continuity across geographic and national borders. The map shows the sampling locations included in the study, with presence of Albanian, Greek or Italian languages.
Credit: Sarno et al. DOI 10.1038/s41598-017-01802-4
The study -- coordinated by the Human Biodiversity and Population Genomics group at the Department of Biological, Geological and Environmental Sciences (BiGeA) of the University of Bologna and funded by the National Geographic Society -- describes the genetic fingerprints of the Mediterranean people with high-density genomic markers and a wide sample of modern populations from Sicily and Southern Italy. Their genetic profiles were analyzed to reconstruct the combination of ancestry components and the demographic history of the region.

As one would expect, populations inhabiting the southeastern shores of Europe are the result of a complex, multi-layered history. One of these layers corresponds to a shared genetic background, extending from Sicily to Cyprus and involving Crete, the Aegean islands and Anatolia. "This shared Mediterranean ancestry possibly traces back to prehistoric times, as the result of multiple migration waves, with peaks during the Neolithic and the Bronze Age," says Stefania Sarno, researcher from the University of Bologna and lead author of the study. Apparently, the ancient Greek expansions (during the Magna Graecia foundation) were only one of the last events in a long history of East-West movements, where the Mediterranean Sea served as a preferential crossroads for the circulation of genes and cultures.

A new perspective for the diffusion of Indo-European languages

One of the most intriguing layers hidden in the Mediterranean genetic landscape involves an important Bronze Age contribution from a Caucasus (or Caucasus-like) source, accompanied by the virtual absence of the typical "Pontic-Caspian" genetic component from the Asian steppe. The latter is a very characteristic genetic signal well represented in North-Central and Eastern Europe, which previous studies associated with the introduction of Indo-European languages to the continent. "These new genomic results from the Mediterranean open a new chapter for the study of the prehistoric movements behind the diffusion of the most represented language family in Europe. The spread of these languages in the Southern regions, where Indo-European languages like Italian, Greek and Albanian are spoken nowadays, cannot be explained with the major contribution from the steppe alone," adds Chiara Barbieri from the Max Planck Institute for the Science of Human History in Jena.

Linguistic and cultural isolates

The current genetic study also focuses on more recent historical layers that contributed to the present-day genetic makeup of the populations sampled, in particular in the cases of long-standing, non-Italian-speaking communities in Italy. For example, mainland Greece and Albania seem to have acquired additional genetic contributions during historic times, most likely related to the Slavic migrations in the Balkans. This recent Balkan genetic ancestry is still evident in some ethno-linguistic minorities of Sicily and Southern Italy, such as the Albanian-speaking Arbereshe. The Arbreshe migrated from Albania to Italy at the end of the Middle Ages and experienced geographic and cultural isolation, which played a part in their distinctive genetic composition.

A different case study is that of Greek-speaking communities from Southern Italy. The genetic features of these groups are compatible with the antiquity of their settlement and with a high cultural permeability with neighboring populations, combined with drift and effects of geographic isolation, as in the case of Calabrian Greeks. "The study of linguistic and cultural isolates in Italy proved to be important to understand our history and our demography," says Alessio Boattini, geneticist and anthropologist from the University of Bologna. "The cases of the Albanian- and Greek-speaking communities of Southern Italy help to shed light into the formation of these cultural and linguistic identities."

"Overall, the study illustrates how both genetic and cultural viewpoints can inform our knowledge of the complex dynamics behind the formation of our Mediterranean heritage, especially in contexts of extensive -- both geographically and temporally -- admixture," says Davide Pettener, professor of Anthropology from the University of Bologna. "These results," adds Prof. Donata Luiselli, who co-led the project, "will be further developed in future studies integrating data from other disciplines, in particular linguistics, archeology and palaeogenomics, with the study of ancient DNA from archaeological remains."

Viking army camp uncovered by archaeologists in England

A huge camp which was home to thousands of Vikings as they prepared to conquer England in the late ninth century has been uncovered by archaeologists.

Established in Torksey, on the banks of the River Trent in Lincolnshire, the camp was used as the Vikings' defensive and strategic position during the winter months.

The research, conducted by archaeologists at the Universities of Sheffield and York, has revealed how the camp was used by thousands of Viking warriors, women and children who lived there temporarily in tented accommodation.

They also used the site as a base to repair ships, melt down stolen loot, manufacture, trade and play games.

Professor Dawn Hadley, who led the research from the University of Sheffield's Department of Archaeology said: "The Vikings' camp at Torksey was much more than just a handful of hardy warriors -- this was a huge base, larger than most contemporary towns, complete with traders, families, feasting, and entertainment.

"From what has been found at the site, we know they were repairing their boats there and melting down looted gold and silver to make ingots -- or bars of metal they used to trade.

"Metal detectorists have also found more than 300 lead game pieces, suggesting the Vikings, including, women and children, were spending a lot of time playing games to pass the time, waiting for spring and the start of their next offensive."

The findings have now been used to create a virtual reality experience giving users an opportunity to experience what life was like in a Viking army camp.

The virtual reality experience has been developed by researchers at the University of York and is part of an exhibition at the Yorkshire Museum that opens on Friday (19 May 2017).

All the scenes featured in the virtual reality experience are based on real objects found by archaeologists and metal detectorists at Torksey.

Professor Julian Richards, from the Department of Archaeology at the University of York, said: "These extraordinary images offer a fascinating snap shot of life at a time of great upheaval in Britain.

"The Vikings had previously often raided exposed coastal monasteries and returned to Scandinavia in winter, but in the later ninth century they came in larger numbers, and decided to stay. This sent a very clear message that they now planned not only to loot and raid -- but to control and conquer."

Dr Gareth Beale from York's Digital Creativity Labs added: "The new research by the Universities of Sheffield and York has been used to create the most realistic images of the camp to date, based on real findings. These images are also believed to be the most realistic Virtual Reality ever created anywhere of the Viking world."

The exact location and scale of the camp in Lincolnshire has been debated for many years, but now the research by Sheffield and York is beginning to reveal the true extent of the camp. It is now thought to be at least 55 hectares in size, bigger than many towns and cities of the time, including York.

There have also been more than a thousand finds by metal detectorists and archaeologists, including over 300 coins. They include more than 100 Arabic silver coins which would have come to the area through established Viking trade routes.

More than 50 pieces of chopped up silver, including brooch fragments and ingots have been found along with rare hackgold. Evidence has been found that these items were being processed at the camp -- chopped up to be melted down. Other finds include the 300 gaming pieces, iron tools, spindle whorls, needles and fishing weights.

Using landscape analysis, the research has been able to reveal the topography of the camp. With the River Trent to the west and surrounding land prone to flooding to this day, its strength as a defensive position becomes clear.

The beginnings of agriculture

The beginnings of agriculture changed human history and has fascinated scientists for centuries.
Researchers from the Grantham Centre for Sustainable Futures at the University of Sheffield have shed light on how hunter-gatherers first began farming and how crops were domesticated to depend on humans.

Domesticated crops have been transformed almost beyond recognition in comparison with their wild relatives -- a change that happened during the early stages of farming in the Stone Age.

For grain crops like cereals, the hallmark of domestication is the loss of natural seed dispersal -- seeds no longer fall off plants but have become dependent on humans or machines to spread them.

Professor Colin Osborne, from the Grantham Centre for Sustainable Futures at the University of Sheffield, said: "We know very little about how agriculture began, because it happened 10,000 years ago -- that's why a number of mysteries are unresolved. For example why hunter-gatherers first began farming, and how were crops domesticated to depend on people.

"One controversy in this area is about the extent to which ancient peoples knew they were domesticating crops. Did they know they were breeding domestication characteristics into crops, or did these characteristics just evolve as the first farmers sowed wild plants into cultivated soil, and tended and harvested them?"

The new research, published in the journal Evolution Letters, shows the impact of domestication on vegetable seed size.

Any selective breeding of vegetables by early farmers would have acted on the leaves, stems or roots that were eaten as food, but should not have directly affected seed size.

Instead, any changes in vegetable seed size must have arisen from natural selection acting on these crops in cultivated fields, or from genetic links to changes in another characteristic like plant or organ size. In the last instance, people might have bred crops to become bigger, and larger seeds would have come along unintentionally.

The University of Sheffield researchers gathered seed size data from a range of crops and found strong evidence for a general enlargement of seeds due to domestication.

They discovered domesticated maize seeds are 15 times bigger than the wild form, soybean seeds are seven times bigger. Wheat, barley and other grain crops had more modest increases in size (60 per cent for barley and 15 per cent for emmer wheat) but these changes are important if they translate into yield.

"We found strong evidence for a general enlargement of seeds due to domestication across seven vegetable species," said Professor Osborne.

"This is especially stunning in a crop like a sweet potato, where people don't even plant seeds, let alone harvest them. The size of this domestication effect falls completely within the range seen in cereals and pulse grains like lentils and beans, raising the possibility that at least part of the seed enlargement in these crops also evolved during domestication without deliberate foresight from early farmers."

Professor Osborne added: "Our findings have important implications for understanding how crops evolved, because they mean that major changes in our staple crops could have arisen without deliberate foresight by early farmers.

"This means that unconscious selection was probably more important in the genesis of our food plants than previously realised. Early increases in the yields of crops might well have evolved in farmers' fields rather than being bred artificially.

Thursday, May 11, 2017

India: Scientists have identified migrating humans from Africa, Iran and Central Asia over a period of 50,000 years

In addition to its vast patchwork of languages, cultures and religions, the Indian Subcontinent also harbours huge genetic diversity. Where did its peoples originate? This is an area of huge controversy among scholars and scientists. A University of Huddersfield PhD student is lead author of an article that tries to answer the question using genetic evidence.

A problem confronting archaeogenetic research into the origins of Indian populations is that there is a dearth of sources, such as preserved skeletal remains that can provide ancient DNA samples. Marina Silva and her co-authors have instead focused on people alive in the Subcontinent today.

They show that some genetic lineages in South Asia are very ancient. The earliest populations were hunter-gatherers who arrived from Africa, where modern humans arose, more than 50,000 years ago. But further waves of settlement came from the direction of Iran, after the last Ice Age ended 10-20,000 years ago, and with the spread of early farming.

These ancient signatures are most clearly seen in the mitochondrial DNA, which tracks the female line of descent. But Y-chromosome variation, which tracks the male line, is very different. Here the major signatures are much more recent. Most controversially, there is a strong signal of immigration from Central Asia, less than 5,000 years ago.

This looks like a sign of the arrival of the first Indo-European speakers, who arose amongst the Bronze Age peoples of the grasslands north of the Caucasus, between the Black and Caspian Seas. They were male-dominated, mobile pastoralists who had domesticated the horse -- and spoke what ultimately became Sanskrit, the language of classical Hinduism -- which more than 200 years ago linguists showed is ultimately related to classical Greek and Latin.

Migrations from the same source also shaped the settlement of Europe and its languages, and this has been the subject of most recent research, said Marina Silva. She has tried to tip the balance back towards India, and her findings are discussed in the article titled A genetic chronology for the Indian Subcontinent points to heavily sex-biased dispersals. It appears in the journal BMC Evolutionary Biology.


Tuesday, May 9, 2017

'Humanlike' ways of thinking evolved 1.8 million years ago, suggests new study

By using highly advanced brain imaging technology to observe modern humans crafting ancient tools, an Indiana University neuroarchaeologist has found evidence that human-like ways of thinking may have emerged as early as 1.8 million years ago.

The results, reported May 8 in the journal Nature Human Behavior, place the appearance of human-like cognition at the emergence of Homo erectus, an early apelike species of human first found in Africa whose evolution predates Neanderthals by nearly 600,000 years.

"This is a significant result because it's commonly thought our most modern forms of cognition only appeared very recently in terms of human evolutionary history," said Shelby S. Putt, a postdoctoral researcher with The Stone Age Institute at Indiana University, who is first author on the study. "But these results suggest the transition from apelike to humanlike ways of thinking and behaving arose surprisingly early."

The study's conclusions are based upon brain activity in modern individuals taught to create two types of ancient tools: simple Oldowan-era "flake tools" -- little more than broken rocks with a jagged edge -- and more complicated Acheulian-era hand axes, which resemble a large arrowhead. Both are formed by smashing rocks together using a process known as "flintknapping."

Oldowan tools, which first appeared about 2.6 million years ago, are among the earliest used by humanity's ancestors. Acheulian-era tool use dates from 1.8 million to 100,000 years ago.

Putt said that neuroarchaeologists look to modern humans to understand how pre-human species evolved cognition since the act of thinking -- unlike fossilized bones or ancient artifacts -- leave no physical trace in the archaeological record.

The methods used to conduct studies on modern humans crafting ancient tools was limited until recently by brain imaging technology. Previous studies depended on placing people within the confines of a functional magnetic resonance imaging machine -- essentially a narrow mental tube -- to observe their brain activity while watching videos of people crafting tools.

Putt's study, by contrast, employed more advanced functional near-infrared spectroscopy -- a device that resembles a lightweight cap with numerous wires used to shine highly sensitive lasers onto the scalp -- to observe brain activity in people as they learned to craft both types of tools with their hands.

In the study, 15 volunteers were taught to craft both types of tools through verbal instruction via videotape. An additional 16 volunteers were shown the same videos without sound to learn toolmaking through nonverbal observation. These experiments were conducted in the lab of John P. Spencer at the University of Iowa, where Putt earned her Ph.D. before joining IU. Spencer is now a faculty member at the University of East Anglia.

The resulting brain scans revealed that visual attention and motor control were required to create the simpler Oldowan tools. A much larger portion of the brain was engaged in the creation of the more complex Acheulian tools, including regions of the brain associated with the integration of visual, auditory and sensorimotor information; the guidance of visual working memory; and higher-order action planning.

"The fact that these more advanced forms of cognition were required to create Acheulean hand axes -- but not simpler Oldowan tools -- means the date for this more humanlike type of cognition can be pushed back to at least 1.8 million years ago, the earliest these tools are found in the archaeological record," Putt said. "Strikingly, these parts of the brain are the same areas engaged in modern activities like playing the piano."

Homo naledi's surprisingly young age opens up more questions on where we come from

Scientists today announced that the Rising Star Cave system has revealed yet more important discoveries, only a year and a half after it was announced that the richest fossil hominin site in Africa had been discovered, and that it contained a new hominin species named Homo naledi by the scientists who described it.

The age of the original Homo naledi remains from the Dinaledi Chamber has been revealed to be startlingly young in age. Homo naledi, which was first announced in September 2015, was alive sometime between 335 and 236 thousand years ago. This places this population of primitive small-brained hominins at a time and place that it is likely they lived alongside Homo sapiens. This is the first time that it has been demonstrated that another species of hominin survived alongside the first humans in Africa.

The research, published today in three papers in the journal eLife, presents the long-awaited age of the naledi fossils from the Dinaledi Chamber and announces the new discovery of a second chamber in the Rising Star cave system, containing additional specimens of Homo naledi. These include a child and a partial skeleton of an adult male with a remarkably well-preserved skull.

The new discovery and research was done by a large team of researchers from the University of the Witwatersrand (Wits), James Cook University, Australia, the University of Wisconsin, Madison, United States, and more than 30 additional international institutions have today announced two major discoveries related to the fossil hominin species Homo naledi.

The team was led by Professor Lee Berger of The University of the Witwatersrand in Johannesburg, South Africa, and a National Geographic Explorer in Residence. The discovery of the second chamber with abundant Homo naledi fossils includes one of the most complete skeletons of a hominin ever discovered, as well as the remains of at least one child and another adult. The discovery of a second chamber has led the team to argue that there is more support for the controversial hypothesis that Homo naledi deliberately disposed of its dead in these remote, hard to reach caverns. 1The dating of Homo naledi is the conclusion of the multi-authored paper entitled: The age of Homo naledi and associated sediments in the Rising Star Cave, South Africa, led by Professor Paul Dirks of James Cook University and the University of the Witwatersrand (Wits).

The naledi date is surprisingly recent. The fossil remains have primitive features that are shared with some of the earliest known fossil members of our genus, such as Homo rudolfensis and Homo habilis, species that lived nearly two million years ago. On the other hand, however, it also shares some features with modern humans. After the description of the new species in 2015, experts had predicted that the fossils should be around the age of these other primitive species. Instead, the fossils from the Dinaledi Chamber are barely more than one-tenth that age.

"The dating of naledi was extremely challenging," noted Dirks, who worked with 19 other scientists from laboratories and institutions around the world, including labs in South Africa and Australia, to establish the age of the fossils. "Eventually, six independent dating methods allowed us to constrain the age of this population of Homo naledi to a period known as the late Middle Pleistocene."

The age for this population of hominins shows that Homo naledi may have survived for as long as two million years alongside other species of hominins in Africa. At such a young age, in a period known as the late Middle Pleistocene, it was previously thought that only Homo sapiens (modern humans) existed in Africa. More critically, it is at precisely this time that we see the rise of what has been called "modern human behaviour" in southern Africa - behaviour attributed, until now, to the rise of modern humans and thought to represent the origins of complex modern human activities such as burial of the dead, self-adornment and complex tools.

The dating game

The team used a combination of optically stimulated luminescence dating of sediments with Uranium-Thorium dating and palaeomagnetic analyses of flowstones to establish how the sediments relate to the geological timescale in the Dinaledi Chamber.

Direct dating of the teeth of Homo naledi, using Uranium series dating (U-series) and electron spin resonance dating (ESR), provided the final age range. "We used double blinds wherever possible," says Professor Jan Kramers of the University of Johannesburg, a uranium dating specialist. Dr. Hannah Hilbert-Wolf, a geologist from James Cook University who also worked on the Dinaledi Chamber, noted that it was crucial to figure out how the sediments within the Dinaledi Chamber are layered, in order to build a framework for understanding all of the dates obtained.

"Of course we were surprised at the young age, but as we realised that all the geological formations in the chamber were young, the U-series and ESR results were perhaps less of a surprise in the end," added Professor Eric Roberts, from James Cook University and Wits, who is one of the few geologists to have ever entered the Dinaledi Chamber, due to the tight 18cm-wide constraints of the entrance chute.

Dr. Marina Elliott, Exploration Scientist at Wits and one of the original "underground astronauts" on the 2013 Rising Star Expedition, says she had always felt that the naledi fossils were 'young'. "I've excavated hundreds of the bones of Homo naledi, and from the first one I touched, I realised that there was something different about the preservation, that they appeared hardly fossilised."

Homo naledi's significant impact

In an accompanying paper, led by Berger, entitled Homo naledi and Pleistocene hominin evolution in subequatorial Africa, the team discuss the importance of finding such a primitive species at such a time and place. They noted that the discovery will have a significant impact on our interpretation of archaeological assemblages and understanding which species made them.

"We can no longer assume that we know which species made which tools, or even assume that it was modern humans that were the innovators of some of these critical technological and behavioural breakthroughs in the archaeological record of Africa," says Berger. "If there is one other species out there that shared the world with 'modern humans' in Africa, it is very likely there are others. We just need to find them."

John Hawks of the University of Wisconsin-Madison and Wits University, an author on all three papers, says: "I think some scientists assumed they knew how human evolution happened, but these new fossil discoveries, plus what we know from genetics, tell us that the southern half of Africa was home to a diversity that we've never seen anywhere else".

"Recently, the fossil hominin record has been full of surprises, and the age of Homo naledi is not going to be the last surprise that comes out of these caves I suspect," adds Berger.

A new chamber and skeleton

In a third paper published at the same time in eLife, entitled New fossil remains of Homo naledi from the Lesedi Chamber, South Africa, the team announces the discovery of a second chamber, within the Rising Star cave system, which contains more remains of Homo naledi.

"The chamber, which we have named the Lesedi Chamber, is more than a hundred meters from the Dinaledi Chamber. It is almost as difficult to access, and also contains spectacular fossils of naledi, including a partial skeleton with a wonderfully complete skull," says Hawks, lead author on the paper describing the new discovery. Fossil remains were first recognised in the chamber by Rick Hunter and Steven Tucker in 2013, as fieldwork was underway in the Dinaledi Chamber.

The name "Lesedi" means "light" in the Setswana language. Excavations in the Lesedi Chamber began later, and would take nearly three years.

No easy access

"To access the Lesedi Chamber is only slightly easier than the Dinaledi Chamber," says Elliott, who was lead excavator of the fossils from the new locality. "After passing through a squeeze of about 25cm, you have to descend along vertical shafts before reaching the chamber. While slightly easier to get to, the Lesedi Chamber is, if anything, more difficult to work in due to the tight spaces involved."

Hawks points out that while the Lesedi Chamber is "easier" to get into than the Dinaledi Chamber, the term is relative. "I have never been inside either of the chambers, and never will be. In fact, I watched Lee Berger being stuck for almost an hour, trying to get out of the narrow underground squeeze of the Lesedi Chamber." Berger eventually had to be extracted using ropes tied to his wrists.

The presence of a second chamber, distant from the first, containing multiple individuals of Homo naledi and almost as difficult to reach as the Dinaledi Chamber, gives an idea of the extraordinary effort it took for Homo naledi to reach these hard-to-get-to places, says Hilbert-Wolf.

"This likely adds weight to the hypothesis that Homo naledi was using dark, remote places to cache its dead," says Hawks. "What are the odds of a second, almost identical occurrence happening by chance?"

So far, the scientists have uncovered more than 130 hominin specimens from the Lesedi Chamber. The bones belong to at least three individuals, but Elliot believes that there are more fossils yet to be discovered. Among the individuals are the skeletal remains of two adults and at least one child. The child is represented by bones of the head and body and would likely have been under five years of age. Of the two adults, one is represented by only a jaw and leg elements, but the other is represented by a partial skeleton, including a mostly complete skull.

Meeting naledi

The team describes the skull of the skeleton as "spectacularly complete". "We finally get a look at the face of Homo naledi," says Peter Schmid of Wits and the University of Zurich, who spent hundreds of hours painstakingly reconstructing the fragile bones to complete the reconstruction.

The skeleton was nicknamed "Neo" by the team, chosen for the Sesotho word meaning "a gift". "The skeleton of Neo is one the most complete ever discovered, and technically even more complete than the famous Lucy fossil, given the preservation of the skull and mandible," says Berger.

The specimens from the Lesedi Chamber are nearly identical in every way to those from the Dinaledi Chamber, a remarkable finding in and of itself. "There is no doubt that they belong to the same species," says Hawks. The Lesedi Chamber fossils have not been dated yet, as dating would require destruction of some of the hominin material. "Once described, we will look at the way forward for establishing the age of these particular fossils," says Dirks. Elliot adds, however, that as the preservation and condition of the finds are practically identical to that of the naledi specimens from the Dinaledi Chamber the team hypothesizes that their age will fall roughly within the same time period.

Berger believes that with thousands of fossils likely remaining in both the Lesedi and Dinaledi Chambers, there are decades of research potential. "We are going to treat ongoing extraction of material from both of these chambers with extreme care and thoughtfulness and with the full knowledge that we need to conserve material for future generations of scientists, and future technological innovations," he says.

52 scientists from 35 departments and Institutions were involved in the research.

Wits Vice-Chancellor and Principal, Professor Adam Habib said: "The search for human origins on the continent of Africa began at Wits and it is wonderful to see this legacy continue with such important discoveries"

"The National Geographic Society has a long history of investing in bold people and transformative ideas," said Gary E. Knell, president and CEO of the National Geographic Society, a funder of the expeditions that recovered the fossils and established their age. "The continued discoveries from Lee Berger and his colleagues showcase why it is critical to support the study of our human origins and other pressing scientific questions."

Public display

The original fossils of these new discoveries, as well as those from the original Rising Star Expedition will be put on public display at the Maropeng, the Official Visitors Centre for the Cradle of Humankind World Heritage Site from May 25th. This exhibit of the largest display of original fossil hominin material in history forms part of an exhibition called "Almost Human".

The exhibition will be housed in 'The Gallery'. This state-of-the-art exhibition space was built as part of the Gauteng Infrastructure Upgrade Project. This is the second completed construction, the first being the upgrade to the Hominin House facilities at Maropeng.

Maropeng is getting ready to receive thousands of visitors wanting to the see the exhibition and the new fossils. In 2015, when Homo naledi was first put on display, some 3 500 visitors per day made their way to Maropeng. "It was an extraordinary thing to experience," says Michael Worsnip, Managing Director of Maropeng. "It was something like a pilgrimage - a wonderful celebration of our heritage as a country, a continent and a planet."

Hominid lived alongside modern humans

JAMES COOK UNIVERSITY's Professor Paul Dirks and Associate Professor Eric Roberts have spent the past few years analysing fossils of the hominid Homo naledi, found deep in a cave system in South Africa in 2013. The pair were involved in investigating the site and describing the find in a paper released in 2015.

Professor Dirks said using state-of-the-art dating techniques at JCU and other facilities in laboratories around the world, they have now found Homo naledi to be between 236,000 and 335,000 years old.

"The oldest dated fossils of Homo sapiens in Africa are around 200,000 years old. And now we have a very primitive looking hominid that probably existed at the same time as them. This is the first time one of these primitive hominids has been found in association with more modern humans in Africa," he said.

Professor Dirks said dating was performed on fossil remains, as well as the surrounding sediments. We have also started work on fossils found in a recently uncovered second chamber deep in the cave system and distinct from the original site of the Homo naledi discovery. He said the implications of the new dates are profound.

"When we first identified the fossils, most of the paleo-anthropologists on site were convinced that they would be a million or two million years old, but we have now shown they are much more recent. It means that a primitive hominid persisted on the landscape in Africa for a very substantial period of time. Well beyond what paleo-anthropologists predicted to be possible."

He said the structure of Homo naledi's hands meant it could have been a toolmaker.

"The new dating puts it on the landscape at a time from which we find lots of tools in Africa in the middle stone-age. One of the implications of the new dates is that it's no longer automatically possible for us to assume that early homosapiens that were making these tools."

Associate Professor Eric Roberts said they are confident of the new dates.

"Much of the initial work on the age range was done here at JCU in our advanced analytic centre. But to get the final date range we used ten different labs and six different techniques which also involved double-blind testing."

Dr Roberts said the second chamber is even deeper in the cave system.

"It's significant because one of the questions after the discovery of the first chamber was whether we had what is known as a 'chimera' - meaning some mythical animal composed of different parts of other animals that doesn't really exist.

"But the new chamber shows the species is what we originally interpreted it as. We have the same morphology on a skeleton and two other partial skulls in the chamber," he said.

Dr Roberts said working in the tight confines of the cave system is challenging.

"The site is difficult to get to and requires some very tight squeezes. Pretty much the only geologists to have worked in the newly discovered second chamber so far are JCU scientists. And the ones that have gotten in are as small as myself or smaller."

Professor Dirks said it's anyone's guess why the hominids were in the cave system to begin with.

"There's a big debate, on whether it's a burial ground or they were trapped there. They could have been chased by lions or other humans, they could have got stuck in the cave. There are enormous storms in the region and there is evidence of meteorite impacts of a similar age in the area. You can speculate all you like, but at the moment the original hypothesis that they were placed there on purpose, still holds."

He said the find shows the history of evolution is far more complicated than just a straight sequential history.

"We have many different branches on the family tree and it is only fairly recently that there is only one survivor on the landscape. The new dating of the fossils opens up all sorts of possibilities for an interchange of tool use, cultural activities and behaviours between Homo naledi and homo sapiens," said Professor Dirks.

Friday, May 5, 2017

The genetic history of Bantu speakers and their relationship to African-Americans

As Bantu-speaking people migrated across Africa, they acquired advantageous genetic mutations through admixture. This material relates to a paper that appeared in the May 5, 2017, issue of Science, published by AAAS. The paper, by E. Patin at Institut Pasteur in Paris, France, and colleagues was titled, "Dispersals and genetic adaptation of Bantu-speaking populations in Africa and North America."
Patin et al., Science (2017) / Etienne Patin / Institut Pasteur
Researchers have used genetic analysis to model the much-debated migration paths, and mingling patterns, of Bantu-speaking people as they disseminated across Africa. Their results reveal how Bantu-speaking peoples (BSPs), which today account for one-third of sub-Saharan Africans, attained gene variations associated with resistance to malaria and lactose digestion. They also shed light on the genetic diversity of modern African-Americans. Many aspects of BSP genetic history, including how they dispersed from western central Africa throughout the continent and whether they acquired advantageous genes in the process, remain unknown.

To gain more insights, Etienne Patin et al. analyzed a total of 548,055 high-quality single nucleotide polymorphisms of 2,055 modern individuals from 57 populations across Africa. Using modelling software, the researchers found that BSPs first moved southward through the rainforest before migrating further south and east, which has been debated. As they dispersed through the rainforest, BSPs encountered local populations of rainforest hunter-gatherers (RHGs), resulting in an admixture event roughly 800 years ago.

Analyses of data allowed the authors to identify adaptive genes that BSPs likely acquired from other African populations, including specific immune-related genes. Lastly, to better understand the genetic contribution of BSPs to present-day African Americans of North America, the team estimated the African ancestry of 5,244 African Americans from various locations on the North American continent. Among other findings, the authors report that African Americans in these locations retain approximately 16% western RHG ancestry, suggesting that African Americans are more genetically diverse than previously suggested.

A first-ever find in Egypt: A funeral garden

The Djehuty Project, led by research professor, José Manuel Galán, from the Spanish National Research Council (CSIC), has discovered a 4,000-year-old funerary garden- the first such garden ever to be found- on the Dra Abu el-Naga hill in Luxor, Egypt. The discovery comes during the 16th year of archaeological excavations which are sponsored this year by Técnicas Reunidas and Indra.

The discoveries made by this project shed light on a key epoch when, for the first time, Thebes (now Luxor) became the capital of the unified kingdom of Upper and Lower Egypt about 4,000 years ago.

Dr. Jose Galán explains, "We knew of the possible existence of these gardens since they appear in illustrations both at the entrances to tombs as well as on tomb walls, where Egyptians would depict how they wanted their funerals to be. The garden itself consisted of a small rectangular area, raised half a meter off the ground and divided into 30 cm2 beds. In addition, next to the garden, two trees were planted. This is the first time that a physical garden has ever been found, and it is therefore the first time that archaeology can confirm what had been deduced from iconography. The discovery and thorough analysis of the garden will provide valuable information about both the botany and the environmental conditions of ancient Thebes, of Luxor 4,000 years ago".

Galán continues, "The plants grown there would have had a symbolic meaning and may have played a role in funerary rituals. Therefore, the garden will also provide information about religious beliefs and practices as well as the culture and society at the time of the Twelfth Dynasty when Thebes became the capital of the unified kingdom of Upper and Lower Egypt for the first time. We know that palm, sycamore and Persea trees were associated with the deceased's power of resurrection. Similarly, plants such as the lettuce had connotations with fertility and therefore a return to life. Now we must wait to see what plants we can identify by analysing the seeds we have collected. It is a spectacular and quite unique find which opens up multiple avenues of research".

"Digging in a necropolis not only allows us to discover details about the world of funerals, religious beliefs and funerary practices, it also helps us discover details about daily life, about society and about the physical environment, both plant and animal. The necropolis thus becomes, as the ancient Egyptians themselves believed, the best way to understand and embrace life", concludes the CSIC researcher.

The garden, or funeral garden, was unearthed in an open courtyard at the entrance of a Middle Kingdom rock-cut tomb very probably from the Twelfth Dynasty, circa 2000 BCE. The garden, measuring 3m x 2m, is raised and is divided into a grid arrangement of 30 cm2 beds distributed in rows of five or seven beds.

According to experts, these small beds may have contained different types of plants and flowers. In addition, at the centre of the raised garden there two beds which are set higher than the others where small trees or shrubs probably grew.

In one corner, the researchers recovered a still upright tamarisk shrub complete with its roots and 30cm-long trunk, beside which was a bowl containing dates and other fruit which may have been given as an offering.

In addition, attached to the facade of the tomb, which the garden is related to for the time being, a small mud-brick chapel (46cm high x 70cm wide x 55cm deep) with three stelae, or stone tombstones, in its interior was also uncovered. These are dated later than the tomb and the garden, coming from the Thirteenth Dynasty, around the year 1800 BCE. One of them belongs to Renef-seneb, and the other to "the soldier ("citizen") Khememi, the son of the lady of the house, Satidenu." On each, reference is made to Montu, a local god from ancient Thebes, and to the funerary gods Ptah, Sokar and Osiris.

"These finds highlight the importance of the area around the Dra Abu el-Naga hill as a sacred centre for a wide range of worship activities during the Middle Kingdom. This helps us understand the high density of tombs in later times as well as the religious symbolism that this area of the necropolis holds", concludes the CSIC researcher.