South Africa's desert-like interior may have been more inviting to our human ancestors

Lining the Cape of South Africa and its southern coast are long chains of caves that nearly 200,000 years ago were surrounded by a lush landscape and plentiful food.

During a glacial phase that lasted between 195,000 to 123,000 years ago, these caves served as refuge to a group of humans that some researchers think were the only people to survive this ice age, called Marine Isotope Stage Six, or MIS6. And in this coastal region, a lot of archaeological research has taken place. Of less interest to archaeologists has been the interior of South Africa, which was thought to be an uninhabited, inhospitable place during at least two waves of ice ages, MIS3 and 2.

Now, a study has shown that the region might have been more fertile and temperate during these two glacial periods than previously thought, and that the region likely played host to human populations living around a series of paleolakes. The study, led by University of Michigan archaeologist Brian Stewart, provides a more comprehensive timeline of the age and stages of these lakes, and shows human fingerprints across the region. The research, funded by the National Geographic Society, is published in the journal PNAS.

"There's this perennial assumption that human population centers were always along the coast and that the interior, especially the southern interior of the Karoo Desert, were largely depopulated for long stretches of time," Stewart said. "The funny thing is that one just has to go into the interior and walk around and notice that there's archaeology everywhere."

But to flag the region as worthy of archaeological attention, the researchers needed to show that humans could have actually lived there. The research team, an international group including researchers from South Africa, the United Kingdom and France, examined a series of super flat areas of land ringed by higher ground. They showed that these regions, called "pans" in Afrikaans, are ancient lake beds, while the areas of higher elevation that encircle them are erosional landforms and sedimentary deposits left over from their ancient shorelines.

This suggests that these time periods were not as dry in this region as previously thought: there would have needed to have been sustained rainfall and humidity to keep these lakes full. The more temperate climate required to sustain lakes also meant the landscape was also able to sustain both vegetation and animals required to support human populations.

Reconstructing the paleolakes

The researchers used a variety of technologies to date and reconstruct these ancient lakes, shorelines and lake bottom deposits, and to recreate the landscape of the region.

These include radiocarbon dating and a technique called luminescence, which measures the radioactivity of tiny crystals of quartz or feldspar that haven't seen the light of day since they were covered by sediment tens of thousands of years earlier. While buried, electrons from radioactive elements common to all sediments get trapped in these crystal matrices at a constant rate. By measuring how many electrons accumulated in the sample and comparing that to the degree of background radioactivity, the researchers can predict its age.

The researchers used these techniques to date columns of sedimentary lakeshore and lake bottom deposits, called lacustrine deposits, found surrounding and within a series of three pans dotted across a region some 100,000 square miles, about the size of Texas. They also aged the shells of freshwater mollusks found scattered throughout the region and embedded within the sedimentary lake deposits.

An aquatic gastropod, Tomichia ventricosa, found at a pan called Swartkolkvloer, was embedded in a column of lacustrine deposits. Together, the deposits and shells were radiocarbon dated to two time periods: approximately 39-55 thousand years before present, and approximately 31-34 thousand years before present.

At another pan called Grootvloer, the researchers found a freshwater mollusk called Unio caffer, which required "perennial freshwater" and the presence of fish to reproduce. These shells and lacustrine deposits in this pan were dated to between approximately 20-22 thousand years before present.

The researchers were also able to predict the area of land the lakes encompassed, as well as how deep they were, based on the height of the lacustrine deposits ringing their shorelines. For example, they determined that the paleolake at Swartkolkvloer was about 83 miles square and 59 feet deep, while the paleolake at Grootvloer was likely about 17 miles square and 62 feet deep. Another pan called Alexanderfontein, some 300 miles northeast near the town of Kimberley, held a lake about 13.5 miles square and 48 feet deep.

Based on these parameters, the researchers knew the lakes would have required a climate drastically different from the one that exists in South Africa's interior today. Using a hydrological model, they determined that evaporation rates within the region were between 20% and 25% lower than what they are today, while precipitation would have been more than 200% higher at Swartkolkvloer and 88% higher at Alexanderfontein.

"In various parts of the interior, between about 60 to about 12,000 years ago, we can see that there were enduring phases of pretty large bodies of water kicking around what used to be thought of as an arid and inhospitable environment," Stewart said. "This was a period that used to be thought of as notoriously dry and freezing cold in the winter. But we've got this evidence for these large lakes existing during this time period."

The researchers say current day regions that have similar climates and rates of precipitation and evaporation are likely northern Botswana, Zambia and Zimbabwe. Based on this estimation and data found from a contemporaneous site called Equus Cave, the researchers think large grazing and browsing mammals would have thrived in this region.

A complex, prehistoric people

Scattered alongside the lakes are human artifacts such as triangular points, bladelets, weathered ostrich shells and other assemblages. Much of these are from the Middle Stone Age, which ranged from about 280,000 years ago to about 25,000 years ago, and the Later Stone Age, which lasted from 25,000 years ago right up to European contact in the 15th century.

"There's Middle Stone Age archaeology just everywhere," Stewart said. "You can't drive anywhere and open the car door and not step on it. It's astounding how much there is."

Stewart says their findings could also expand the region where archaeologists think humans became more behaviorally complex. Over the past decades, researchers have found evidence that humans living in coastal South Africa started making the leap into complex thought, showing some of the earliest signs of behavioral complexity. It was thought that both climate and nutrient stability -- including the rich omega fatty acids gleaned from seafood -- allowed humans here to become behaviorally modern.

The group's work may challenge this idea by suggesting that favorable conditions for hunter-gatherers were not confined to the coastline but probably characterized many regions as climates changed, including the interior, current-day desert.

"Ours is a basin-wide study with much more macro scale implications. It also involves some of these areas that are just inland of this coastal and mountain belt that's dominated the archaeological narratives for so long," Stewart said. "Just inland of this area is a region that has been, for a long time, portrayed as hostile, and it just simply appears not to have been the case for big chunks of time -- with the caveat that we need information on temperature depressions to understand how humans dealt with that."

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Human ancestors preferred mosaic landscapes and high ecosystem diversity

A new study published in the journal Science by an international team finds that early human species adapted to mosaic landscapes and diverse food resources, which would have increased our ancestor's resilience to past shifts in climate.

Our genus Homo evolved over the past 3 million years -- a period of increasing warm/cold climate fluctuations. How early human species have adapted to the intensification of climate extremes, ice ages, and large-scale shifts in landscapes and vegetation remains elusive. Did our ancestors adjust to local environmental changes over time, or did they seek out more stable environments with diverse food resources? Was our human evolution influenced more by temporal changes in climate, or by the spatial character of the environment?

To test these fundamental hypotheses on human evolution and adaptation quantitively, the research team used a compilation of more than three thousand well-dated human fossil specimens and archeological sites, representing six different human species, in combination with realistic climate and vegetation model simulations, covering the past 3 million years. The scientists focused their analysis on biomes -- geographic regions which are characterized by similar climates, plants, and animal communities (e.g., savannah, rainforest, or tundra).

"For the archeological and anthropological sites and corresponding ages, we extracted the local biome types from our climate-driven vegetation model. This revealed which biomes were favored by the extinct hominin species H. ergaster, H. habilis, H. erectus, H. heidelbergensis, and H. neanderthalensis andbyour direct ancestors -- H. sapiens.," said Elke Zeller, Ph.D. student from the IBS Center for Climate Physics at Pusan National University, South Korea, and lead author of the study.

According to their analysis, the scientists found that earlier African groups preferred to live in open environments, such as grassland and dry shrubland. Migrating into Eurasia around 1.8 million years ago, hominins, such as H. erectus and later H. heidelbergensis and H. neanderthalensis developed higher tolerances to other biomes over time, including temperate and boreal forests. "To survive as forest-dwellers, these groups developed more advanced stone tools and likely also social skills," said Prof. Pasquale Raia, from the Università di Napoli Federico II, Italy, co-author of the study. Eventually, H. sapiens emerged around 200,000 years ago in Africa, quickly becoming the master of all trades. Mobile, flexible, and competitive, our direct ancestors, unlike any other species before, survived in harsh environments such as deserts and tundra.

When further looking into the preferred landscape characteristics, the scientists found a significant clustering of early human occupation sites in regions with increased biome diversity. "What that means is that our human ancestors had a liking for mosaic landscapes, with a great variety of plant and animal resources in close proximity," said Prof. Axel Timmermann, co-author of the study and Director of the IBS Center for Climate Physics in South Korea. The results indicate that ecosystem diversity played a key role in human evolution.

The authors demonstrated this preference for mosaic landscapes for the first time on continental scales and propose a new Diversity Selection Hypothesis: Homo species, and H. sapiens, in particular, were uniquely equipped to exploit heterogeneous biomes. "Our analysis shows the crucial importance of landscape and plant diversity as a selective element for humans and as a potential driver for socio-cultural developments" adds Elke Zeller. Elucidating how vegetation shifts have shaped human sustenance, the new Science study provides an unprecedented view into human prehistory and survival strategies.

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2.9-million-year-old butchery site reopens case of who made first stone tools

Along the shores of Africa's Lake Victoria in Kenya roughly 2.9 million years ago, early human ancestors used some of the oldest stone tools ever found to butcher hippos and pound plant material, according to new research led by scientists with the Smithsonian's National Museum of Natural History and Queens College, CUNY, as well as the National Museums of Kenya, Liverpool John Moores University and the Cleveland Museum of Natural History.

The study, published today, Feb. 9, in the journal Science, presents what are likely to be the oldest examples of a hugely important stone-age innovation known to scientists as the Oldowan toolkit, as well as the oldest evidence of hominins consuming very large animals. Though multiple lines of evidence suggest the artifacts are likely to be about 2.9 million years old, the artifacts can be more conservatively dated to between 2.6 and 3 million years old, said lead study author Thomas Plummer of Queens College, research associate in the scientific team of the Smithsonian's Human Origins Program.

Excavations at the site, named Nyayanga and located on the Homa Peninsula in western Kenya, also produced a pair of massive molars belonging to the human species' close evolutionary relative Paranthropus. The teeth are the oldest fossilized Paranthropus remains yet found, and their presence at a site loaded with stone tools raises intriguing questions about which human ancestor made those tools, said Rick Potts, senior author of the study and the National Museum of Natural History's Peter Buck Chair of Human Origins.

"The assumption among researchers has long been that only the genus Homo, to which humans belong, was capable of making stone tools," Potts said. "But finding Paranthropus alongside these stone tools opens up a fascinating whodunnit."

Whichever hominin lineage was responsible for the tools, they were found more than 800 miles from the previously known oldest examples of Oldowan stone tools -- 2.6-million-year-old tools unearthed in Ledi-Geraru, Ethiopia. This greatly expands the area associated with Oldowan technology's earliest origins. Further, the stone tools from the site in Ethiopia could not be tied to any particular function or use, leading to speculation about what the Oldowan toolkit's earliest uses might have been.

Through analysis of the wear patterns on the stone tools and animal bones discovered at Nyayanga, Kenya, the team behind this latest discovery shows that these stone tools were used by early human ancestors to process a wide range of materials and foods, including plants, meat and even bone marrow.

The Oldowan toolkit includes three types of stone tools: hammerstones, cores and flakes. Hammerstones can be used for hitting other rocks to create tools or for pounding other materials. Cores typically have an angular or oval shape, and when struck at an angle with a hammerstone, the core splits off a piece, or flake, that can be used as a cutting or scraping edge or further refined using a hammerstone.

"With these tools you can crush better than an elephant's molar can and cut better than a lion's canine can," Potts said. "Oldowan technology was like suddenly evolving a brand-new set of teeth outside your body, and it opened up a new variety of foods on the African savannah to our ancestors."

Potts and Plummer were first drawn to the Homa Peninsula in Kenya by reports of large numbers of fossilized baboon-like monkeys named Theropithecus oswaldi, which are often found alongside evidence of human ancestors. After many visits to the peninsula, a local man named Peter Onyango working with the team suggested they check out fossils and stone tools eroding from a nearby site that was ultimately named Nyayanga after an adjacent beach.

Beginning in 2015, a series of excavations at Nyayanga returned a trove of 330 artifacts, 1,776 animal bones and the two hominin molars identified as belonging to Paranthropus. The artifacts, Plummer said, were clearly part of the stone-age technological breakthrough that was the Oldowan toolkit.

Compared to the only other stone tools known to have preceded them -- a set of 3.3-million-year-old artifacts unearthed at a site called Lomekwi 3, just west of Lake Turkana in Kenya -- Oldowan tools were a significant upgrade in sophistication. Oldowan tools were systematically produced and often fashioned using what is known as "freehand percussion," meaning the core was held in one hand and then struck with a hammerstone being wielded by the opposing hand at just the right angle to produce a flake -- a technique that requires significant dexterity and skill.

By contrast, most of the artifacts from Lomekwi 3 were created by using large stationary rocks as anvils, with the toolmaker either banging a core against the flat anvil stone to create flakes or by setting the core down on the anvil and striking it with a hammerstone. These more rudimentary modes of fabrication resulted in larger, cruder and more haphazard-looking tools.

Over time, the Oldowan toolkit spread all the way across Africa and even as far as modern-day Georgia and China, and it was not meaningfully replaced or amended until some 1.7 million years ago when the hand-axes of the Acheulean first appeared.

As part of their study, the researchers conducted microscopic analysis of wear patterns on the stone tools to determine how they were used, and they examined any bones seen to exhibit potential cut marks or other kinds of damage that might have come from stone tools.

The site featured at least three individual hippos. Two of these incomplete skeletons included bones that showed signs of butchery. The team found a deep cut mark on one hippo's rib fragment and a series of four short, parallel cuts on the shin bone of another. Plummer said they also found antelope bones that showed evidence of hominins slicing away flesh with stone flakes or of having been crushed by hammerstones to extract marrow.

The analysis of wear patterns on 30 of the stone tools found at the site showed that they had been used to cut, scrape and pound both animals and plants. Because fire would not be harnessed by hominins for another 2 million years or so, these stone toolmakers would have eaten everything raw, perhaps pounding the meat into something like a hippo tartare to make it easier to chew.

Using a combination of dating techniques, including the rate of decay of radioactive elements, reversals of Earth's magnetic field and the presence of certain fossil animals whose timing in the fossil record is well established, the research team was able to date the items recovered from Nyayanga to between 2.58 and 3 million years old.

"This is one of the oldest if not the oldest example of Oldowan technology," Plummer said. "This shows the toolkit was more widely distributed at an earlier date than people realized, and that it was used to process a wide variety of plant and animal tissues. We don't know for sure what the adaptive significance was but the variety of uses suggests it was important to these hominins."

The discovery of teeth from the muscular-jawed Paranthropus alongside these stone tools begs the question of whether it might have been that lineage rather than the Homo genus that was the architect of the earliest Oldowan stone tools, or perhaps even that multiple lineages were making these tools at roughly the same time.

The excavations behind this study offer a snapshot of the world humans' ancestors inhabited and help illustrate the ways that stone technology allowed these early hominins to adapt to different environments and, ultimately, give rise to the human species.

"East Africa wasn't a stable cradle for our species' ancestors," Potts said. "It was more of a boiling cauldron of environmental change, with downpours and droughts and a diverse, ever-changing menu of foods. Oldowan stone tools could have cut and pounded through it all and helped early toolmakers adapt to new places and new opportunities, whether it's a dead hippo or a starchy root."

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Footprints claimed as evidence of ice age humans in North America need better dating, new research shows

The wide expanse of an ancient lakebed in New Mexico holds the preserved footprints of life that roamed millennia ago. Giant sloths and mammoths left their mark, and alongside them, signs of our human ancestors. Research published in September 2021 claimed that these footprints are "definitive evidence of human occupation of North America" during the last ice age, dating back to between 23 and 21 thousand years ago. Now, a new study disputes the evidence of such an early age.

Scientists from DRI, Kansas State University, the University of Nevada, Reno, and Oregon State University caution in Quaternary Research that the dating evidence is insufficient for claims that would so radically alter our understanding of when, and how, humans first arrived in North America. Using the same dating method and materials, the new study shows that the footprints could have been left thousands of years later than originally claimed.

"I read the original Science article on the human footprints at White Sands and was initially struck not only by how tremendous the footprints were on their own, but how important accurate dating would be," says Charles Oviatt, emeritus professor of geology at Kansas State University and one of the new study's authors. "I saw potential problems with the scientific tests of the dates reported in the Science paper."

"It really does throw a lot of what we think we know into question," says David Rhode, Ph.D., a paleoecologist at DRI and co-author of the new study. "That's why it's important to really nail down this age, and why we're suggesting that we need better evidence."

Archaeologists and historians use a number of methods to determine the timing of historic events. Based on these methods, scientists tend to agree that the earliest known dates of humanity's colonization of North America lie between 14 and 16 thousand years ago, after the last ice age. If the original claims are correct, current chronological models in fields as varied as paleogenetics and regional geochronology would need to be reevaluated.

"23 to 21 thousand years ago is in a timeframe where you need to really pay attention to how people got into North America," says Rhode. "At that time, there was a huge, mile-high mountain range of ice covering Canada to the north, and the pathway down the Pacific Coast wasn't very accommodating either -- so it may have been that people had to come here much earlier than that."

By studying ancient DNA from human fossils and using rates of genetic change (a sort of molecular clock using DNA), paleogeneticists surmise that the American Southwest was first occupied no earlier than 20 thousand years ago. If the footprints are older, it throws into question the use and integrity of these genetic models. It's possible that the ages from one study at a single site in a New Mexico lake basin are valid, and that age estimates from a variety of other fields are invalid, the authors write, but more robust evidence is needed to confirm the claims.

At the center of the debate are the tiny seeds of an aquatic plant used to age the footprints. The timeframe for the seeds was identified using radiocarbon dating methods, in which researchers examine a type of carbon known as Carbon-14. Carbon-14 originates in the atmosphere and is absorbed by plants through photosynthesis. These carbon isotopes decay at a constant rate over time, and comparing the amount of Carbon-14 in the atmosphere to the amount present in fossilized plant material allows scientists to determine their approximate age. But the plant species used, Ruppia cirrhosa, grows underwater and therefore obtains much of its carbon for photosynthesis not directly from the atmosphere as terrestrial plants do, but from dissolved carbon atoms in the water.

"While the researchers recognize the problem, they underestimate the basic biology of the plant," says Rhode. "For the most part, it's using the carbon it finds in the lake waters. And in most cases, that means it's taking in carbon from sources other than the contemporary atmosphere -- sources which are usually pretty old."

This method is likely to give radiocarbon-based age estimates of the plant that are much older than the plants themselves. Ancient carbon enters the groundwater of the Lake Otero basin from eroded bedrock of the Tularosa Valley and the surrounding mountains, and occurs in extensive calcium carbonate deposits throughout the basin.

The authors demonstrated this effect by examining Ruppia plant material with a known age from the same region. Botanists collected living Ruppia plants from a nearby spring-fed pond in 1947 and archived them at the University of New Mexico herbarium. Using the same radiocarbon dating method, the plants that were alive in 1947 returned a radiocarbon date suggesting they were about 7400 years old, an offset resulting from the use of ancient groundwater by the plant. The authors note that if the ages of the Ruppia seeds dated from the human footprints were also offset by roughly 7400 years, their real age would be between 15 and 13 thousand years old -- a date which aligns with ages of several other known early North American archaeological sites.

The dating of the footprints can be resolved through other methods, including radiocarbon dating of terrestrial plants (which use atmospheric carbon and not carbon from groundwater) and optically stimulated luminescence dating of quartz found in the sediment, the authors write.

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Ancient genomes reveal hidden history of human adaptation

The use of ancient DNA, including samples of human remains around 45,000 years old, has shed light on a previously unknown aspect of human evolution.

Dr Yassine Souilmi, Group Leader at the University of Adelaide's Australian Centre for Ancient DNA, co-led the new study published in Nature Ecology and Evolution.

"It was widely believed the genetics of our human ancestors didn't change due to environmental pressures as much as other animals, due to our enhanced communication skills and ability to make and use tools," Dr Souilmi said.

"However, by comparing modern genomes with ancient DNA, we discovered more than 50 cases of an initially rare beneficial genetic variant becoming prevalent across all members of ancient human groups.

"In contrast to many other species, evidence for this type of adaptive genetic change has been inconsistent in humans. This discovery consequently challenges the prevailing view of human adaptation, and gives us a new and exciting insight into how humans have adapted to the novel environmental pressures they encountered as we spread across the planet."

Co-lead author Dr Ray Tobler -- an Adjunct Fellow at the University of Adelaide and a DECRA fellow at the Australian National University -- said examining ancient DNA has been critical in unlocking the secrets of human evolution.

"We believed historical mixing events between human groups might have hidden signs of genetic changes in modern human genomes," Dr Tobler said.

"We examined DNA from more than 1,000 ancient genomes, the oldest which was around 45,000 years old, to see if certain types of genetic adaptation had been more common in our history than studies of modern genomes had suggested."

Professor Christian Huber, a senior author of the research paper, is an Adjunct Fellow at the University of Adelaide and an Assistant Professor at Penn State University.

"The use of ancient genomes was crucial because they preceded major historical mixing events that have radically reshaped modern European genetic ancestry," Professor Huber said.

"This allowed the recovery of historical signs of adaptation that are invisible to standard analysis of modern genomes."

Established in 2005, the Australian Centre for Ancient DNA is a world leader in the research and development of advanced ancient DNA approaches for evolutionary, environmental and conservation applications.

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Fossils in the 'Cradle of Humankind' may be more than a million years older than previously thought

The earth doesn't give up its secrets easily -- not even in the "Cradle of Humankind" in South Africa, where a wealth of fossils relating to human evolution have been found.

For decades, scientists have studied these fossils of early human ancestors and their long-lost relatives. Now, a dating method developed by a Purdue University geologist just pushed the age of some of these fossils found at the site of Sterkfontein Caves back more than a million years. This would make them older than Dinkinesh, also called Lucy, the world's most famous Australopithecus fossil.

The "Cradle of Humankind" is a UNESCO World Heritage Site in South Africa that comprises a variety of fossil-bearing cave deposits, including at Sterkfontein Caves. Sterkfontein was made famous by the discovery of the first adult Australopithecus, an ancient hominin, in 1936. Hominins includes humans and our ancestral relatives, but not the other great apes. Since then, hundreds of Australopithecus fossils have been found there, including the well-known Mrs. Ples, and the nearly complete skeleton known as Little Foot. Paleoanthropologists and other scientists have studied Sterkfontein and other cave sites in the Cradle of Humankind for decades to shed light on human and environmental evolution over the past 4 million years.

Darryl Granger, a professor of earth, atmospheric, and planetary sciences in Purdue University's College of Science, is one of those scientists, working as part of an international team. Granger specializes in dating geologic deposits, including those in caves. As a doctoral student, he devised a method for dating buried cave sediments that is now used by researchers all over the world. His previous work at Sterkfontein dated the Little Foot skeleton to about 3.7 million years old, but scientists are still debating the age of other fossils at the site.

In a study published in the Proceedings of the National Academy of Sciences, Granger and a team of scientists including researchers from the University of the Witwatersrand in Johannesburg, South Africa and the University Toulouse Jean Jaurès in France, have discovered that not only Little Foot, but all of the Australopithecus-bearing cave sediments date from about 3.4 to 3.7 million years old, rather than 2-2.5 million years old as scientists previously theorized. That age places these fossils toward the beginning of the Australopithecus era, rather than near the end. Dinkinesh, who hails from Ethiopia, is 3.2 million years old, and her species, Australopithecus africanus, hails back to about 3.9 million years old.

Sterkfontein is a deep and complex cave system that preserves a long history of hominin occupation of the area. Understanding the dates of the fossils here can be tricky, as rocks and bones tumbled to the bottom of a deep hole in the ground, and there are few ways to date cave sediments.

In East Africa, where many hominin fossils have been found, the Great Rift Valley volcanoes lay down layers of ash that can be dated. Researchers use those layers to estimate how old a fossil is. In South Africa -- especially in a cave -- the scientists don't have that luxury. They typically use other animal fossils found around the bones to estimate their age or calcite flowstone deposited in the cave. But bones can shift in the cave, and young flowstone can be deposited in old sediment, making those methods potentially incorrect. A more accurate method is to date the actual rocks in which the fossils were found. The concrete-like matrix that embeds the fossil, called breccia, is the material Granger and his team analyze.

"Sterkfontein has more Australopithecus fossils than anywhere else in the world," Granger said. "But it's hard to get a good date on them. People have looked at the animal fossils found near them and compared the ages of cave features like flowstones and gotten a range of different dates. What our data does is resolve these controversies. It shows that these fossils are old -- much older than we originally thought."

Granger and the team used accelerator mass spectrometry to measure radioactive nuclides in the rocks, as well as geologic mapping and an intimate understanding of how cave sediments accumulate to determine the age of the Australopithecus-bearing sediments at Sterkfontein,

Granger and the research group at the Purdue Rare Isotope Measurement Laboratory (PRIME Lab) study so-called cosmogenic nuclides and what they can reveal about the history of fossils, geological features and rock. Cosmogenic nuclides are extremely rare isotopes produced by cosmic rays -- high-energy particles that constantly bombard the earth. These incoming cosmic rays have enough energy to cause nuclear reactions inside rocks at the ground surface, creating new, radioactive isotopes within the mineral crystals. An example is aluminum-26: aluminum that is missing a neutron and slowly decays to turn into magnesium over a period of millions of years. Since aluminum-26 is formed when a rock is exposed at the surface, but not after it has been deeply buried in a cave, PRIME lab researchers can date cave sediments (and the fossils within them) by measuring levels of aluminum-26 in tandem with another cosmogenic nuclide, beryllium-10.

In addition to the new dates at Sterkfontein based on cosmogenic nuclides, the research team made careful maps of the cave deposits and showed how animal fossils of different ages would have been mixed together during excavations in the 1930s and 1940s, leading to decades of confusion with the previous ages. "What I hope is that this convinces people that this dating method gives reliable results," Granger said. "Using this method, we can more accurately place ancient humans and their relatives in the correct time periods, in Africa, and elsewhere across the world."

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Tooth study prompts rethink of human evolution

A study into tooth wear in a group of wild Japanese macaques has significant implications for the study of human evolution, a University of Otago study has shown.

Lead author Dr Ian Towle and Dr Carolina Loch, of the Sir John Walsh Research Institute, in collaboration with colleagues from Japan, studied root grooves and large uniform scratches in the macaques' teeth, which had previously only been described in fossil humans.

"Unusual wear on our fossil ancestors' teeth is thought to be unique to humans and demonstrates specific types of tool use. These types of wear have also been considered some of the earliest evidence of cultural habits for our ancestors," Dr Towle says.

"However, our research suggests this idea may need reconsidering, since we describe identical tooth wear in a group of wild monkeys that do not use tools.

"This research raises questions for our understanding of cultural changes during human evolution and suggests we may need to reassess early evidence of cultural habits."

The study, published in the American Journal of Biological Anthropology, concluded the 'toothpick'-like grooves on back teeth and large uniform scratches on the macaques' front teeth were actually caused by something more mundane, yet still surprising -- eating shellfish from rocks and accidentally chewing grit and sand with their food.

This macaque group is well-known for undertaking remarkable behaviours, including washing foods in water, and consuming fish. They have been studied for more than 70 years and have not been seen using tools or other items that could cause the unusual tooth wear observed.

Dr Towle has been studying tooth wear and pathologies in a wide variety of primate species and was "extremely surprised" to find this type of tooth wear in a group of wild monkeys.

"Up until now, the large scratches in the front teeth of fossil humans have been considered to be caused by a behaviour called 'stuff and cut', in which an item such as an animal hide is held between the front teeth and a stone tool is used for slicing. Similarly, 'toothpick' grooves are thought to be caused by tools being placed between back teeth to remove food debris or relieve pain.

"Although this does not mean hominins were not placing tools in their mouths, our study suggests the accidental ingestion of grit and/or normal food processing behaviours could also be responsible for these atypical wear patterns."

Dr Towle believes the findings provide insight into how researchers interpret cultural changes through the course of human evolution.

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Extinct reptile discovery reveals earliest origins of human teeth, study finds

A new extinct reptile species has shed light on how our earliest ancestors became top predators by modifying their teeth in response to environmental instability around 300 million years ago.

In findings published in Royal Society Open Science, researchers at the University of Bristol have discovered that this evolutionary adaptation laid the foundations for the incisor, canine and molar teeth that all mammals -- including humans -- possess today.

Shashajaia is one of the most primitive members of a group called the Sphenacodontoidea, which includes the famous sail-backed Dimetrodon, and mammal-like reptiles known as therapsids, which eventually evolved into mammals. It is remarkable for its age and anatomy, possessing a very unique set of teeth that set it apart from other synapsids -- meaning the animal lineage that mammals belong to -- of the time.

Dr Suresh Singh of the School of Earth Sciences explained: "The teeth show clear differentiation in shape between the front and back of the jaw, organised into distinct regions. This is the basic precursor of what mammals have today -- incisors and canines up front, with molars in the back. This is the oldest record of such teeth in our evolutionary tree."

The novel dentition of Shashajaia demonstratesthat large, canine-like differentiated teeth were present in synapsids by the Late Carboniferous period -- a time famous for giant insects and the global swampy rainforests that produced much of our coal deposits.

By analytically comparing the tooth variation observed in Shashajaia with other synapsids, the study suggests that distinctive, specialised teeth likely emerged in our synapsid ancestors as a predatory adaptation to help them catch prey at a time when global climate change approximately 300 million years ago saw once-prevalent Carboniferous wetlands replaced by more arid, seasonal environments. These new, more changeable conditions brought a change in the availability and diversity of prey.

Lead author Dr Adam Huttenlocker of the University of Southern California said: "Canine-like teeth in small sphenacodonts like Shashajaia might have facilitated a fast, raptorial bite in riparian habitats where a mix of terrestrial and semi-aquatic prey could be found in abundance."

The new reptile is one of the oldest synapsids. It was named "Shashajaia bermani," which translates as Berman's bear heart, to honour the 51-year career of veteran palaeontologist, Dr David Berman of the Carnegie Museum of Natural History, as well as the local Navajo people of the discovery site within the Bears Ears National Monument, Utah.

Dr Singh said: "The study is a testament to Dr Berman who originally discovered the fossil site in 1989, and his decades of work on synapsids and other early tetrapods from the Bears Ears region of Utah which helped to justify the Bears Ears National Monument in 2016."

The site is located within an area known as the Valley of the Gods and is of huge importance to palaeontologists.

Read more at Science Daily

Tooth cavities provide unique ecological insight into living primates and fossil humans

Tooth decay is a common and unfortunate problem for many of us, but two University of Otago studies show it is also an issue for other primates, as well as our fossil relatives and ancestors.

Dr Ian Towle, the former Sir Thomas Sidey Postdoctoral Fellow in Otago's Faculty of Dentistry, says cavities are often considered to be a modern disease unique to humans, related to a diet rich in processed sugary foods. However, he says there is growing evidence tooth decay also occurs to a certain extent in other animal groups.

"Our new research shows caries also occurs in wild primates in low frequencies, although this is highly variable among groups and the teeth affected also vary," he says.

"This research helps us understand changes in diet and behaviour in human evolution; it also provides insight into particular behaviours in our living primate relatives."

For the research, published in the American Journal of Primatology and South African Journal of Science, Dr Towle and colleagues analysed more than 8000 extant primate and fossil human teeth and assessed variation in tooth decay patterns in relation to diet and behaviour.

They found 3.3 per cent of teeth in living primates had caries, which is similar to the incidence in fossil humans (ranging from 1 to 4 per cent of teeth in different species). However, all caries in the fossil humans samples studied were on back teeth, whereas the vast majority in living primates were on the front teeth.

"The fascinating feeding behaviours of animals such as chimpanzees, using their large front teeth to help suck sugary liquid out of figs, contributes to creating caries patterns rarely seen in humans.

"Indeed, in humans our back teeth are mostly affected by dental decay, whereas in other primates it's typically the front teeth," Dr Towle says.

Another interesting aspect of this research was that female chimpanzees had more caries than males (9.3 per cent compared to 1.8 per cent), with similar sex differences often evident in humans.

The work also revealed how similar decay patterns between captive primates and humans are, highlighting how primates often don't undertake specific natural behaviours in captivity.

"Caries occurred throughout human evolution and that doesn't seem to change much for millions of years, with less than 5 per cent of teeth affected. However, with the onset of agriculture, this increased rapidly to more than 20 per cent of teeth having cavities in some samples."

Read more at Science Daily

Fossil elephant cranium reveals key adaptations that enabled its species to thrive as grasslands spread across eastern Africa

A remarkably well-preserved fossil elephant cranium from Kenya is helping scientists understand how its species became the dominant elephant in eastern Africa several million years ago, a time when a cooler, drier climate allowed grasslands to spread and when habitually bipedal human ancestors first appeared on the landscape.

Dated to 4.5 million years ago and recovered from a site on the northeast side of Lake Turkana, it is the only well-preserved elephant cranium -- the portion of the skull that encloses the brain -- from that time. It isabout 85% intact and holds a wealth of previously unavailable anatomical detail, according to University of Michigan paleontologist William Sanders.

Known by its museum number, KNM-ER 63642, the roughly 2-ton cranium belonged to a massive adult male of the species Loxodonta adaurora, an extinct evolutionary cousin of modern African elephants but not a direct ancestor.

KNM-ER 63642 is both impressively immense and unexpectedly modern in aspect, displaying adaptations that likely gave L. adaurora an edge when competing with other large mammals for grasses, according to Sanders, lead author of a study published online Oct. 21 in the journal Palaeovertebrata. Co-authors include Meave and Louise Leakey, who led the recovery effort and who are best known for the discovery of early hominid specimens and artifacts from Lake Turkana and elsewhere.

The L. adaurora cranium is striking because it is raised and compressed from front to back, suggesting a novel alignment of chewing muscles well-suited for the efficient shearing of grasses. In addition, the animal's molars are higher-crowned and had thicker coatings of cementum than other early elephants, making the teeth more resistant to the wear common in animals that feed on grasses close to the ground.

"The evident synchronization of morphological adaptations and feeding behavior revealed by this study of Loxodonta adaurora may explain why it became the dominant elephant species of the early Pliocene," said Sanders, who has studied fossil elephants and their relatives for nearly 40 years in Africa and Arabia.

Eastern Africa was home to seven or eight known species of early elephants at the time, along with horses, antelope, rhinos, pigs and hippos. Many of these animals were becoming grazers and competing for the available grasses.

"The adaptations of L. adaurora put it at a great advantage over more primitive elephants, in that it could probably use less energy to chew more food and live longer to have more offspring," said Sanders, associate research scientist at the U-M Museum of Paleontology and in the Department of Anthropology.

Recovery, conservation, dating, description and identification of the elephant cranium involved collaborative work between researchers and techniciansfrom the Turkana Basin Institute, National Museums of Kenya, University of Michigan, Rutgers University, Smithsonian Institution and University of Utah.

KNM-ER 63642 was discovered in 2013 by a member of the Koobi Fora Research Project from a single molar that was visible at the surface.

Excavation revealed the presence of a nearly complete cranium. The tusks and the jawbone were missing, and no other remains from that individual were recovered. The adult male is estimated to have been 30 to 34 years old at death.

The fossilized cranium, together with the plaster jacket that protected it and some attached sediment, weighed about 2 tons. Based on a previous study of the skeleton from another L. adaurora adult male with a similar-sized skull, this individual likely weighed about 9 tons and probably stood about 12 feet at the shoulder -- bigger than average male elephants of modern times.

"In my opinion, this elephant skull is by far the most impressive specimen that we have in the Kenyan paleontological collection from Lake Turkana, both in its completeness and in its size," said paleontologist and study co-author Louise Leakey of the Koobi Fora Research Project. "When the teeth were seen on the surface, we had no idea that a complete cranium would be uncovered, and the excavation and recovery operation was both challenging and exciting."

KNM-ER 63642 is now permanently housed at the Turkana Basin Institute's facility in Ileret, Kenya. It is the only well-preserved elephant cranium from the interval beginning with the origin of elephants 8 million years ago and ending 3.5 million years ago, according to Sanders.

In addition to providing a trove of insights about the anatomy of early elephants, the newly described cranium also deepens our understanding of the connections between those creatures and our earliest human ancestors, the habitually bipedal australopithecines.

Loxodonta adaurora and other early elephants coexisted with two well-known australopithecine species in eastern Africa: Australopithecusanamensis, recovered by Meave Leakey in and nearby the Lake Turkana Basin, Kenya, and A. afarensis, found at sites in Hadar, Ethiopia, and Laetoli, Tanzania.

In the early Pliocene, as grassy woodlands and grasslands spread across eastern Africa, the australopithecines would have benefited from the presence of elephants. The animals' feeding activities helped keep grasses low to the ground, which would have allowed our upright ancestors to see over the vegetation and to watch for predators.

Elephants also disrupt closed woodlands and create open areas by knocking over trees, uprooting shrubs, and trampling paths through dense forest. And they spread nutrients and grass seed in their dung.

"The origins and early successes of our own biological family are tied to elephants," Sanders said. "Their presence on the landscape created more open conditions that favored the activities and adaptations of our first bipedal hominin ancestors.

"From this perspective, it is ironically tragic that current human activities of encroaching land use, poaching and human-driven climate change are now threatening the extinction of the mammal lineage that helped us to begin our own evolutionary journey."

Read more at Science Daily

New species of human ancestor named: Homo bodoensis

An international team of researchers, led by University of Winnipeg palaeoanthropologist Dr. Mirjana Roksandic, has announced the naming of a new species of human ancestor, Homo bodoensis. This species lived in Africa during the Middle Pleistocene, around half a million years ago, and was the direct ancestor of modern humans.

The Middle Pleistocene (now renamed Chibanian and dated to 774,000-129,000 years ago) is important because it saw the rise of our own species (Homo sapiens) in Africa, our closest relatives, and the Neanderthals (Homo neanderthalensis) in Europe.

However, human evolution during this age is poorly understood, a problem which paleoanthropologists call "the muddle in the middle." The announcement of Homo bodoensis hopes to bring some clarity to this puzzling, but important chapter in human evolution.

The new name is based on a reassessment of existing fossils from Africa and Eurasia from this time period. Traditionally, these fossils have been variably assigned to either Homo heidelbergensis or Homo rhodesiensis, both of which carried multiple, often contradictory definitions.

"Talking about human evolution during this time period became impossible due to the lack of proper terminology that acknowledges human geographic variation" according to Roksandic, lead author on the study.

Recently, DNA evidence has shown that some fossils in Europe called H. heidelbergensis were actually early Neanderthals, making the name redundant. For the same reason, the name needs to be abandoned when describing fossil humans from east Asia according to co-author, Xiu-Jie Wu (Institute of Vertebrate Paleontology and Paleoanthropology, Beijing, China).

Further muddling the narrative, African fossils dated to this period have been called at times both H. heidelbergensis and H. rhodesiensis. H. rhodesiensis is poorly defined and the name has never been widely accepted. This is partly due to its association with Cecil Rhodes and the horrendous crimes carried out during colonial rule in Africa -- an unacceptable honour in light of the important work being done toward decolonizing science.

The name "bodoensis" derives from a skull found in Bodo D'ar, Ethiopia, and the new species is understood to be a direct human ancestor. Under the new classification, H. bodoensis will describe most Middle Pleistocene humans from Africa and some from Southeast Europe, while many from the latter continent will be reclassified as Neanderthals,

The co-first author Predrag Radovic (Faculty of Philosophy, University of Belgrade, Serbia) says, "Terms need to be clear in science, to facilitate communication. They should not be treated as absolute when they contradict the fossil record."

Read more at Science Daily

What big teeth you have: Tooth root surface area can determine primate size

An often overlooked feature could give scientists new insight into the lives of ancient primate species. Researchers from North Carolina State University have developed formulas that can calculate the body size of a primate based on the root size of its teeth. The formulas could allow researchers to make use of partial and incomplete fossils in order to learn how ancient primates -- including human ancestors -- interacted with their environment.

Ashley Deutsch, NC State graduate student and first author of a paper describing the research, wanted to know if it was possible to determine what a primate's diet was without having the actual tooth crowns at hand -- by looking instead at the roots.

What we commonly think of when we think of teeth isn't the whole story -- the part that does the chewing is merely the crown. The part that keeps the tooth anchored in the jaw is the root.

"The tooth root transmits the force of the jaws into the food," says Adam Hartstone-Rose, professor of biological sciences at NC State and paper coauthor. "You can think of the root as the handle of a hammer -- the handle size is related to the amount of force you can put into the hammer. So if a hammer has a small handle, it will have a small head to hammer small things. In the same way, a big tooth root can transmit more force to the tooth's crown to crush more obdurate foods."

Deutsch and the research team initially set out to determine whether tooth roots could indicate the shape of the tooth's crown, thus telling them what particular primates preferred to eat. Using computer tomography, Deutsch analyzed and calculated the tooth root surface area -- or area of contact where the root fits into the jaw -- of 70 primates from 75 species, ranging in size from tiny mouse lemurs to great apes.

"It was a bit like trying to figure out if you have an axe or hammer based on the shape of the handle," Deutsch says.

Ultimately, she found that the tooth roots only related to diet in a few lineages (for example, lemurs); however, she was able to determine how big the primates were across all lineages.

Deutsch developed a series of formulas based on the relationship between the tooth root surface of a molar or premolar -- the teeth located between canines and molars -- and primate body mass. The formulas can be used to estimate body mass of primates with more or less specificity, depending upon whether their class is known. The formulas can also explain up to 96% of variation in body mass within the examined primate sample.

But perhaps the most useful application of the equation will be with fossils that are currently of little use to anthropologists and paleontologists.

"As long as the fossil has a bit of root you can use the formulas even if the tooth crowns are missing," Deutsch says. "Fossils are often maddeningly incomplete, but now those incomplete pieces can be useful, and they could answer questions about our own lineage, like how big our ancient ancestors were."

Deutsch hopes to continue refining the existing equations and expand the work beyond primates to other mammals, including carnivores.

"Ashley has looked at something that is often preserved but also generally ignored by science and found it might hold answers to one of the most important ecological questions," Hartstone-Rose says. "Just knowing how big an animal is tells you a lot about how it interacted with the environment. And that could give us a lot of insight into our own ancient history."

Read more at Science Daily

Analysis of famous fossil helps unlock when humans and apes diverged

 A long-awaited, high-tech analysis of the upper body of famed fossil "Little Foot" opens a window to a pivotal period when human ancestors diverged from apes, new USC research shows.

Little Foot's shoulder assembly proved key to interpreting an early branch of the human evolutionary tree. Scientists at the Keck School of Medicine of USC focused on its so-called pectoral girdle, which includes collarbones, shoulder blades and joints.

Although other parts of Little Foot, especially its legs, show humanlike traits for upright walking, the shoulder components are clearly apelike, supporting arms surprisingly well suited for suspending from branches or shimmying up and down trees rather than throwing a projectile or dangling astride the torso like humans.

The Little Foot fossil provides the best evidence yet of how human ancestors used their arms more than 3 million years ago, said Kristian J. Carlson, lead author of the study and associate professor of clinical integrative anatomical sciences at the Keck School of Medicine.

"Little Foot is the Rosetta stone for early human ancestors," he said. "When we compare the shoulder assembly with living humans and apes, it shows that Little Foot's shoulder was probably a good model of the shoulder of the common ancestor of humans and other African apes like chimpanzees and gorillas."

The apelike characteristics will likely attract considerable intrigue as science teams around the world have been examining different parts of the skeleton to find clues to human origins. The USC-led study, which also involved researchers at the University of Wisconsin, the University of Liverpool and the University of the Witwatersrand in South Africa, among others, was published today in the Journal of Human Evolution.

The journal devoted a special issue to Little Foot analyses from a global research group, which looked at other parts of the creature's skeleton. The process is somewhat akin to the story of blind men and the elephant, each examining one part in coordination with others to explain the whole of something that's not fully understood.

The Little Foot fossil is a rare specimen because it's a near-complete skeleton of an Australopithecus individual much older than most other human ancestors. The creature, probably an old female, stood about 4 feet tall with long legs suitable for bipedal motion when it lived some 3.67 million years ago. Called "Little Foot" because the first bones recovered consisted of a few small foot bones, the remains were discovered in a cave in South Africa in the 1990s. Researchers have spent years excavating it from its rock encasement and subjecting it to high-tech analysis.

While not as widely known as the Lucy skeleton, another Australopithecus individual unearthed in East Africa in the 1970s, Carlson said Little Foot is older and more complete.

The USC-led research team zeroed in on the shoulder assemblies because Little Foot provides the oldest and most intact example of this anatomy ever found. Those bones provide telltale clues of how an animal moves. In human evolution, he said, these parts had to change form before our ancestors could live life free of trees, walk the open savannah and use their arms for functions other than supporting the weight of the individual.

The scientists compared the creature's shoulder parts to apes, hominins and humans. Little Foot was a creature adapted to living in trees because the pectoral girdle suggests a creature that climbed trees, hung below branches and used its hands overhead to support its weight.

For example, the scapula, or shoulder blade, has a big, high ridge to attach heavy muscles similar to gorillas and chimpanzees. The shoulder joint, where the humerus connects, sits at an oblique angle, useful for stabilizing the body and lessening tensile loads on shoulder ligaments when an ape hangs beneath branches. The shoulder also has a sturdy, apelike reinforcing structure, the ventral bar. And the collarbone has a distinctive S-shaped curve commonly found in apes.

Those conclusions mean that the structural similarities in the shoulder between humans and African apes are much more recent, and persisted much longer, than has been proposed, Carlson said.

"We see incontrovertible evidence in Little Foot that the arm of our ancestors at 3.67 million years ago was still being used to bear substantial weight during arboreal movements in trees for climbing or hanging beneath branches," he said. "In fact, based on comparisons with living humans and apes, we propose that the shoulder morphology and function of Little Foot is a good model for that of the common ancestor of humans and chimpanzees 7 million to 8 million years ago."

The scientists were able to achieve remarkably clear images of the fossils. That's because the bones, painstakingly excavated for many years, are in good condition and uniquely complete. The scientists examined them using micro-CT scans, which can detect minute features on the surface of an object, peer deep inside a bone, measure the density of an object and generate a 3D model without harming the fossil.

Read more at Science Daily

Neanderthals had the capacity to perceive and produce human speech

 Neandertals -- the closest ancestor to modern humans -- possessed the ability to perceive and produce human speech, according to a new study published by an international multidisciplinary team of researchers including Binghamton University anthropology professor Rolf Quam and graduate student Alex Velez.

"This is one of the most important studies I have been involved in during my career," says Quam. "The results are solid and clearly show the Neandertals had the capacity to perceive and produce human speech. This is one of the very few current, ongoing research lines relying on fossil evidence to study the evolution of language, a notoriously tricky subject in anthropology."

The evolution of language, and the linguistic capacities in Neandertals in particular, is a long-standing question in human evolution.

"For decades, one of the central questions in human evolutionary studies has been whether the human form of communication, spoken language, was also present in any other species of human ancestor, especially the Neandertals," says coauthor Juan Luis Arsuaga, Professor of Paleontology at the Universidad Complutense de Madrid and co-director of the excavations and research at the Atapuerca sites. The latest study has reconstructed how Neandertals heard to draw some inferences about how they may have communicated.

The study relied on high resolution CT scans to create virtual 3D models of the ear structures in Homo sapiens and Neandertals as well as earlier fossils from the site of Atapuerca that represent ancestors of the Neandertals. Data collected on the 3D models were entered into a software-based model, developed in the field of auditory bioengineering, to estimate the hearing abilities up to 5 kHz, which encompasses most of the frequency range of modern human speech sounds. Compared with the Atapuerca fossils, the Neandertals showed slightly better hearing between 4-5 kHz, resembling modern humans more closely.

In addition, the researchers were able to calculate the frequency range of maximum sensitivity, technically known as the occupied bandwidth, in each species. The occupied bandwidth is related to the communication system, such that a wider bandwidth allows for a larger number of easily distinguishable acoustic signals to be used in the oral communication of a species. This, in turn, improves the efficiency of communication, the ability to deliver a clear message in the shortest amount of time. The Neandertals show a wider bandwidth compared with their ancestors from Atapuerca, more closely resembling modern humans in this feature.

"This really is the key," says Mercedes Conde-Valverde, professor at the Universidad de Alcalá in Spain and lead author of the study. "The presence of similar hearing abilities, particularly the bandwidth, demonstrates that the Neandertals possessed a communication system that was as complex and efficient as modern human speech."

"One of the other interesting results from the study was the suggestion that Neandertal speech likely included an increased use of consonants," said Quam. "Most previous studies of Neandertal speech capacities focused on their ability to produce the main vowels in English spoken language. However, we feel this emphasis is misplaced, since the use of consonants is a way to include more information in the vocal signal and it also separates human speech and language from the communication patterns in nearly all other primates. The fact that our study picked up on this is a really interesting aspect of the research and is a novel suggestion regarding the linguistic capacities in our fossil ancestors."

Thus, Neandertals had a similar capacity to us to produce the sounds of human speech, and their ear was "tuned" to perceive these frequencies. This change in the auditory capacities in Neandertals, compared with their ancestors from Atapuerca, parallels archaeological evidence for increasingly complex behavioral patterns, including changes in stone tool technology, domestication of fire and possible symbolic practices. Thus, the study provides strong evidence in favor of the coevolution of increasingly complex behaviors and increasing efficiency in vocal communication throughout the course of human evolution.

The team behind the new study has been developing this research line for nearly two decades, and has ongoing collaborations to extend the analyses to additional fossil species. For the moment, however, the new results are exciting.

Read more at Science Daily

Denisovan DNA in the genome of early East Asians

 Researchers analyzed the genome of the oldest human fossil found in Mongolia to date and show that the 34,000-year-old woman inherited around 25 percent of her DNA from western Eurasians, demonstrating that people moved across the Eurasian continent shortly after it had first been settled by the ancestors of present-day populations. This individual and a 40,000-year-old individual from China also carried DNA from Denisovans, an extinct form of hominins that inhabited Asia before modern humans arrived.

In 2006, miners discovered a hominin skullcap with peculiar morphological features in the Salkhit Valley of the Norovlin county in eastern Mongolia. It was initially referred to as Mongolanthropus and thought to be a Neandertal or even a Homo erectus. The remains of the "Salkhit" individual represent the only Pleistocene hominin fossil found in the country.

Ancient DNA extracted from the skullcap shows that it belonged to a female modern human who lived 34,000 ago and was more related to Asians than to Europeans. Comparisons to the only other early East Asian individual genetically studied to date, a 40,000-year-old male from Tianyuan Cave outside Beijing (China), show that the two individuals are related to each other. However, they differ insofar that a quarter of the ancestry of the Salkhit individual derived from western Eurasians, probably via admixture with ancient Siberians.

Migration and interaction

"This is direct evidence that modern human communities in East Asia were already quite cosmopolitan earlier than 34,000 years ago," says Diyendo Massilani, lead author of the study and researcher at the Max-Planck Institute for Evolutionary Anthropology. "This rare specimen shows that migration and interactions among populations across Eurasia happened frequently already some 35,000 years ago."

The researchers used a new method developed at the Max-Planck Institute for Evolutionary Anthropology to find segments of DNA from extinct hominins in the Salkhit and Tianyuan genomes. They found that the two genomes contain not only Neandertal DNA but also DNA from Denisovans, an elusive Asian relative of Neandertals. "It is fascinating to see that the ancestors of the oldest humans in East Asia from whom we have been able to obtain genetic data had already mixed with Denisovans, an extinct form of hominins that has contributed ancestry to present-day populations in Asia and Oceania," says Byambaa Gunchinsuren, a researcher at the Institute of Archaeology of the Mongolian Academy of Sciences. "This is direct evidence that Denisovans and modern humans had met and mixed more than 40,000 years ago."

Read more at Science Daily

DNA from an ancient, unidentified ancestor was passed down to humans living today

 A new analysis of ancient genomes suggests that different branches of the human family tree interbred multiple times, and that some humans carry DNA from an archaic, unknown ancestor. Melissa Hubisz and Amy Williams of Cornell University and Adam Siepel of Cold Spring Harbor Laboratory report these findings in a study published 6th August in PLOS Genetics.

Roughly 50,000 years ago, a group of humans migrated out of Africa and interbred with Neanderthals in Eurasia. But that's not the only time that our ancient human ancestors and their relatives swapped DNA. The sequencing of genomes from Neanderthals and a less well-known ancient group, the Denisovans, has yielded many new insights into these interbreeding events and into the movement of ancient human populations. In the new paper, the researchers developed an algorithm for analyzing genomes that can identify segments of DNA that came from other species, even if that gene flow occurred thousands of years ago and came from an unknown source. They used the algorithm to look at genomes from two Neanderthals, a Denisovan and two African humans. The researchers found evidence that 3 percent of the Neanderthal genome came from ancient humans, and estimate that the interbreeding occurred between 200,000 and 300,000 years ago. Furthermore, 1 percent of the Denisovan genome likely came from an unknown and more distant relative, possibly Homo erectus, and about 15% of these "super-archaic" regions may have been passed down to modern humans who are alive today.

The new findings confirm previously reported cases of gene flow between ancient humans and their relatives, and also point to new instances of interbreeding. Given the number of these events, the researchers say that genetic exchange was likely whenever two groups overlapped in time and space. Their new algorithm solves the challenging problem of identifying tiny remnants of gene flow that occurred hundreds of thousands of years ago, when only a handful of ancient genomes are available. This algorithm may also be useful for studying gene flow in other species where interbreeding occurred, such as in wolves and dogs.

"What I think is exciting about this work is that it demonstrates what you can learn about deep human history by jointly reconstructing the full evolutionary history of a collection of sequences from both modern humans and archaic hominins," said author Adam Siepel. "This new algorithm that Melissa has developed, ARGweaver-D, is able to reach back further in time than any other computational method I've seen. It seems to be especially powerful for detecting ancient introgression."

 From Science Daily

Discovery of oldest bow and arrow technology in Eurasia

The origins of human innovation have traditionally been sought in the grasslands and coasts of Africa or the temperate environments of Europe. More extreme environments, such as the tropical rainforests of Asia, have been largely overlooked, despite their deep history of human occupation. A new study provides the earliest evidence for bow-and-arrow use, and perhaps the making of clothes, outside of Africa ~48-45,000 years ago -- in the tropics of Sri Lanka.

The island of Sri Lanka in the Indian Ocean, just south of the Indian subcontinent, is home to the earliest fossils of our species, Homo sapiens, in South Asia. It also preserves clear evidence for human occupation and the use of tropical rainforest environments outside of Africa from ~48,000 to 3,000 years ago -- refuting the idea that these supposedly resource-poor environments acted as barriers for migrating Pleistocene humans. The question as to exactly how humans obtained rainforest resources -- including fast-moving food sources like monkeys and squirrels -- remains unresolved.

In this new study, published in Science Advances, an international team of researchers from the Max Planck Institute for the Science of Human History (MPI-SHH) in Germany, Griffith University in Australia and the Department of Archaeology, Government of Sri Lanka, present evidence for the earliest use of bow-and-arrow technologies by humans anywhere outside of Africa. At ~48,000 years old, these tools are earlier than the first similar technology found in Europe. Clear evidence for use on the preserved bone arrowheads shows that they were likely used for hunting difficult-to-catch rainforest prey. Not only that, but the scientists show that other bone tools may have been used for making nets or clothing in tropical settings, dramatically altering traditional assumptions about how certain human innovations were linked with specific environmental requirements.

Hunting in the open and sheltering from the cold?

European cultural products in the form of cave art, amazingly detailed bone carvings, bone tool technologies, and tailored clothing have been frequently held up as the pinnacle of Late Pleistocene human cultural development. There, symbolic and technological innovations have been seen as key survival mechanisms equipping expanding populations to face cold northern climates. Meanwhile, discoveries of older bow-and-arrow technology and artistic or symbolic behaviors in open grassland or coastal settings in Africa have framed 'savannah' and marine environments, respectively, as key drivers behind early hunting and cultural experiments by Pleistocene humans in their evolutionary homeland.

As co-author of the new study, Patrick Roberts of the MPI-SHH argues that "this traditional focus has meant that other parts of Africa, Asia, Australasia, and the Americas have often been side-lined in discussions of the origins of material culture, such as novel projectile hunting methods or cultural innovations associated with our species." Nevertheless, the last twenty years have highlighted how Pleistocene humans occupied and adapted to a variety of extreme environments as they migrated beyond Africa, including deserts, high-altitude settings and tropical rainforests such as those of Sri Lanka.

A tropical home

The new study saw scientists turn to the beautifully preserved material culture from the cave of Fa-Hien Lena, deep in the heart of Sri Lanka's Wet Zone forests. As co-author Oshan Wedage, PhD at MPI-SHH, states, "Fa-Hien Lena has emerged as one of South Asia's most important archaeological sites since the 1980s, preserving remains of our species, their tools, and their prey in a tropical context." Some of the main finds from the site include remarkable single and doubled pointed bone tools that scientists had suspected were used in the exploitation of tropical resources. Direct proof had been lacking, however, in the absence of detailed high-powered microscopic analysis.

Michelle Langley of Griffith University, the lead author of the new study, is an expert in the study of microscopic traces of tool use and the creation of symbolic material culture in Pleistocene contexts. Applying cutting edge methods to the Fa-Hien Lena material confirmed the researchers' hypothesis. As Langley states, "the fractures on the points indicate damage through high-powered impact -- something usually seen in the use of bow-and-arrow hunting of animals. This evidence is earlier than similar findings in Southeast Asia 32,000 years ago and is currently the earliest clear evidence for bow-and-arrow use beyond the African continent."

The evidence for early human innovation did not stop there. Applying the same microscopic approach to other bone tools, the team identified implements which seem to have been associated with freshwater fishing in nearby tropical streams, as well as the working of fiber to make nets or clothing. "We also found clear evidence for the production of colored beads from mineral ochre and the refined making of shell beads traded from the coast, at a similar age to other 'social signaling' materials found in Eurasia and Southeast Asia, roughly 45,000 years ago," says Michelle Langley. Together, this reveals a complex, early human social network in the tropics of South Asia.

A flexible toolkit for new hunting grounds

The new study highlights that archaeologists can no longer link specific technological, symbolic, or cultural developments in Pleistocene humans to a single region or environment. "The Sri Lankan evidence shows that the invention of bows-and-arrows, clothing, and symbolic signaling occurred multiple times and in multiple different places, including within the tropical rainforests of Asia," says co-author Michael Petraglia of the MPI-SHH. In addition to insulation in cold environments, clothes may have also helped against tropical mosquitoes, "and instead of just hunting large grassland mammals," adds zooarchaeologist Noel Amano, another MPI-SHH co-author, "bows and arrows helped humans procure small, tree-dwelling primates and rodents."

Read more at Science Daily

Homo naledi juvenile remains offers clues to how our ancestors grew up

A partial skeleton of Homo naledi represents a rare case of an immature individual, shedding light on the evolution of growth and development in human ancestry, according to a study published April 1, 2020 in the open-access journal PLOS ONE by Debra Bolter of Modesto Junior College in California and the University of the Witwatersrand, Johannesburg, and colleagues.

Much research has gone into the evolution of ancient hominins -- human relatives and ancestors -- but little is known about their growth and development. Most hominin fossils represent adult individuals, and remains of developmentally young hominins are rare. This has left a gap in our understanding of how our ancient relatives grew from young into adults, and how modern human growth patterns evolved.

In this study, Bolter and colleagues examined fossils from the Dinaledi Chamber of the Rising Star Cave System in South Africa. This site is famous for providing abundant remains of the hominin Homo naledi, including individuals ranging from infants to adult. These fossils date to the late Middle Pleistocene, between 335,000 and 226,000 years ago, possibly overlapping in time with the earliest members of our own species. The team identified a collection of arm and leg bones and a partial jaw as the remains of a single young individual designated DH7.

The bones and teeth of DH7 were not fully developed and display a mixture of maturity patterns seen in modern humans and earlier hominins. DH7 is estimated to be similar in its developmental stage to immature specimens of other fossil hominins between 8-11 years old at death. The authors note, however, that if Homo naledi had a slower growth rate like modern humans, DH7 might have been as old as 15. Further study is needed to assess how Homo naledi grew and where it fits into the evolution of human growth and development.

Bolter adds: The rare juvenile Homo naledi partial skeleton will shed light on whether this extinct species is more human-like in its development, or more primitive. The findings help reconstruct the selective pressures that shaped extended maturity in our own species.

From Science Daily

When three species of human ancestor walked the Earth

Homo erectus word cloud

An international team, including Arizona State University researcher Gary Schwartz, have unearthed the earliest known skull of Homo erectus, the first of our ancestors to be nearly human-like in their anatomy and aspects of their behavior.

Years of painstaking excavation at the fossil-rich site of Drimolen, nestled within the Cradle of Humankind (a UNESCO World Heritage site located just 40 kilometers or around 25 miles northwest of Johannesburg in South Africa), has resulted in the recovery of several new and important fossils. The skull, attributed to Homo erectus, is securely dated to be two million years old.

Published this week in Science, the international team of nearly 30 scientists from five countries shared details of this skull -- the most ancient fossil Homo erectus known -- and other fossils from this site and discuss how these new finds are forcing us to rewrite a part of our species' evolutionary history.

The high-resolution dating of Drimolen's fossil deposits demonstrates the age of the new skull to pre-date Homo erectus specimens from other sites within and outside of Africa by at least 100,000 to 200,000 years and thus confirms an African origin for the species.

The skull, reconstructed from more than 150 separate fragments, is of an individual likely aged between three and six years old, giving scientists a rare glimpse into childhood growth and development in these early human ancestors.

Additional fossils recovered from Drimolen belong to a different species -- in fact, a different genus of ancient human altogether -- the more heavily built, robust human ancestor Paranthropus robustus, known to also occur at several nearby cave sites preserving fossils of the same geological age. A third, distinctive species, Australopithecus sediba, is known from two-million-year old deposits of an ancient cave site virtually down the road from Drimolen.

"Unlike the situation today, where we are the only human species, two million years ago our direct ancestor was not alone," said project director and lead researcher from La Trobe University in Australia, Andy Herries.

Gary Schwartz, a paleoanthropologist and research associate with ASU's Institute of Human Origins, participated in the excavations and recovery of the new cranium, and as an expert in the evolution of growth and development, is continuing his work with the research team to analyze the many infant and juvenile specimens found at the site.

"What is really exciting is the discovery that during this same narrow time slice, at just around two million years ago, there were three very different types of ancient human ancestors roaming the same small landscape," said Schwartz.

"We don't yet know whether they interacted directly, but their presence raises the possibility that these ancient fossil humans evolved strategies to divvy up the landscape and its resources in some way to enable them to live in such close proximity." Schwartz is also an Associate Professor in the School of Human Evolution and Social Change.

The ability to date Drimolen's ancient cave deposits with such a high degree of precision, using a range of different dating techniques, allowed the team to address important broader questions about human evolution in this region of Africa.

Paper coauthor Justin Adams from Monash University (Australia) is a specialist in reconstructing paleohabitats based on the animals preserved at fossil sites, said the discovery now allows us to address what role changing habitats, resources, and the unique biological adaptations of early Homo erectus may have played in the eventual extinction of Australopithecus sediba in South Africa.

"The discovery of the earliest Homo erectus marks a milestone for South African fossil heritage," says project codirector and University of Johannesburg doctoral student Stephanie Baker.

Fieldwork will continue at Drimolen, expanding the excavations to include even more ancient components of the cave and to provide a more in-depth glimpse at the forces shaping human evolution in this part of the African continent.

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Oldest ever human genetic evidence clarifies dispute over our ancestors

DNA illustration

Genetic information from an 800,000-year-old human fossil has been retrieved for the first time. The results from the University of Copenhagen shed light on one of the branching points in the human family tree, reaching much further back in time than previously possible.

An important advancement in human evolution studies has been achieved after scientists retrieved the oldest human genetic data set from an 800,000-year-old tooth belonging to the hominin species Homo antecessor.

The findings by scientists from the University of Copenhagen (Denmark), in collaboration with colleagues from the CENIEH (National Research Center on Human Evolution) in Burgos, Spain, and other institutions, are published April 1st in Nature.

"Ancient protein analysis provides evidence for a close relationship between Homo antecessor, us (Homo sapiens), Neanderthals, and Denisovans. Our results support the idea that Homo antecessor was a sister group to the group containing Homo sapiens, Neanderthals, and Denisovans," says Frido Welker, Postdoctoral Research Fellow at the Globe Institute, University of Copenhagen, and first author on the paper.

Reconstructing the human family tree

By using a technique called mass spectrometry, researchers sequenced ancient proteins from dental enamel, and confidently determined the position of Homo antecessor in the human family tree.

The new molecular method, palaeoproteomics, developed by researchers at the Faculty of Health and Medical Sciences, University of Copenhagen, enables scientists to retrieve molecular evidence to accurately reconstruct human evolution from further back in time than ever before.

The human and the chimpanzee lineages split from each other about 9-7 million years ago. Scientists have relentlessly aimed to better understand the evolutionary relations between our species and the others, all now extinct, in the human lineage.

"Much of what we know so far is based either on the results of ancient DNA analysis, or on observations of the shape and the physical structure of fossils. Because of the chemical degradation of DNA over time, the oldest human DNA retrieved so far is dated at no more than approximately 400,000 years," says Enrico Cappellini, Associate Professor at the Globe Institute, University of Copenhagen, and leading author on the paper.

"Now, the analysis of ancient proteins with mass spectrometry, an approach commonly known as palaeoproteomics, allow us to overcome these limits," he adds.

Theories on human evolution

The fossils analyzed by the researchers were found by palaeoanthropologist José María Bermúdez de Castro and his team in 1994 in stratigraphic level TD6 from the Gran Dolina cave site, one of the archaeological and paleontological sites of the Sierra de Atapuerca, Spain.

Initial observations led to conclude that Homo antecessor was the last common ancestor to modern humans and Neanderthals, a conclusion based on the physical shape and appearance of the fossils. In the following years, the exact relation between Homo antecessor and other human groups, like ourselves and Neanderthals, has been discussed intensely among anthropologists.

Although the hypothesis that Homo antecessor could be the common ancestor of Neanderthals and modern humans is very difficult to fit into the evolutionary scenario of the genus Homo, new findings in TD6 and subsequent studies revealed several characters shared among the human species found in Atapuerca and the Neanderthals. In addition, new studies confirmed that the facial features of Homo antecessor are very similar to those of Homo sapiens and very different from those of the Neanderthals and their more recent ancestors.

"I am happy that the protein study provides evidence that the Homo antecessor species may be closely related to the last common ancestor of Homo sapiens, Neanderthals, and Denisovans. The features shared by Homo antecessor with these hominins clearly appeared much earlier than previously thought. Homo antecessor would therefore be a basal species of the emerging humanity formed by Neanderthals, Denisovans, and modern humans," adds José María Bermúdez de Castro, Scientific Co-director of the excavations in Atapuerca and co-corresponding author on the paper.

World class-expertise

Findings like these are made possible through an extensive collaboration between different research fields: from paleoanthropology to biochemistry, proteomics and population genomics.

Retrieval of ancient genetic material from the rarest fossil specimens requires top quality expertise and equipment. This is the reason behind the now ten-years-long strategic collaboration between Enrico Cappellini and Jesper Velgaard Olsen, Professor at the Novo Nordisk Foundation Center for Protein Research, University of Copenhagen and co-author on the paper.

"This study is an exciting milestone in palaeoproteomics. Using state of the art mass spectrometry, we determine the sequence of amino acids within protein remains from Homo antecessor dental enamel. We can then compare the ancient protein sequences we 'read' to those of other hominins, for example Neanderthals and Homo sapiens, to determine how they are genetically related," says Jesper Velgaard Olsen.

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