Toba supereruption unveils new insights into early human migration

Modern humans dispersed from Africa multiple times, but the event that led to global expansion occurred less than 100,000 years ago. Some researchers hypothesize that dispersals were restricted to "green corridors" formed during humid intervals when food was abundant and human populations expanded in lockstep with their environments. But a new study in Nature, including ASU researchers Curtis Marean, Christopher Campisano, and Jayde Hirniak, suggests that humans also may have dispersed during arid intervals along "blue highways" created by seasonal rivers. Researchers also found evidence of cooking and stone tools that represent the oldest evidence of archery.

Working in the Horn of Africa, researchers have uncovered evidence showing how early modern humans survived in the wake of the eruption of Toba, one of the largest supervolcanoes in history, some 74,000 years ago. The behavioral flexibility of these people not only helped them live through the supereruption but may have facilitated the later dispersal of modern humans out of Africa and across the rest of the world.

"This study confirms the results from Pinnacle Point in South Africa -- the eruption of Toba may have changed the environment in Africa, but people adapted and survived that eruption-caused environmental change," said Marean, research scientist with the Institute of Human Origins and Foundation Professor with the School of Human Evolution and Social Change.

The team investigated the Shinfa-Metema 1 site in the lowlands of present-day northwestern Ethiopia along the Shinfa River, a tributary of the Blue Nile River.

The supereruption occurred during the middle of the time when the site was occupied and is documented by tiny glass shards whose chemistry matches that of Toba.

Pinpoint timing through cryptotephra

"One of the ground-breaking implications of this study," said Marean, "is that with the new cryptotephra methods developed for our prior study in South Africa, and now applied here to Ethiopia, we can correlate sites across Africa, and perhaps the world, at a resolution of several weeks of time."

Cryptotephra are signature volcanic glass shards that can range from 80-20 microns in size, which is smaller than the diameter of a human hair. To extract these microscopic shards from archaeological sediment requires patience and great attention to detail.

"Searching for cryptotephra at these archaeological sites is like looking for a needle in a haystack, but not knowing if there is even a needle. However, having the ability to correlate sites 5,000 miles apart, and potentially further, to within weeks instead of thousands of years makes it all worth it," said Christopher Campisano, research scientist with the Institute of Human Origins and professor with the School of Human Evolution and Social Change.

"This study, once again," said Campisano, "highlights the importance of the University of Nevada-Las Vegas/Arizona State University team pushing the limits for successfully analyzing extremely low abundance cryptotephra to date and correlate archaeological sites across Africa."

The methods for identifying low abundance cryptotephra at Pinnacle Point were first developed at University of Nevada Las Vegas led by the late Gene Smith and Racheal Johnsen and now carried on at Arizona State University's Sediment and TEphra Preparation (STEP) Lab.

School of Human Evolution and Social Change graduate student Jayde Hirniak led ASU's effort to create its own cryptotephra lab -- the STEP Lab -- working with Campisano and building on methods developed at UNLV. Hirniak also collaborated with cryptotephra labs in the United Kingdom that work with sediment samples preserving hundreds or thousands of glass shards. Now Hirniak's primary expertise is in tephrochronology, which involves the use of volcanic ash to link archaeological and paleoenvironmental records and place them on the same timeline, which was her contribution to this research.

"Our lab at ASU was built to process extremely low abundance cryptotephra horizons (<10 shards per gram) using a highly specialized technique. There are only a few labs in the world with these capabilities," said Hirniak.

Migrations along "blue highways"

Based on isotope geochemistry of the teeth of fossil mammals and ostrich eggshells, they concluded that the site was occupied by humans during a time with long dry seasons on a par with some of the most seasonally arid habitats in East Africa today. Additional findings suggest that when river flows stopped during dry periods, people adapted by hunting animals that came to the remaining waterholes to drink. As waterholes continued to shrink, it became easier to capture fish without any special equipment, and diets shifted more heavily to fish.

Its climatic effects appear to have produced a longer dry season, causing people in the area to rely even more on fish. The shrinking of the waterholes may also have pushed humans to migrate outward in search of more food.

"As people depleted food in and around a given dry season waterhole, they were likely forced to move to new waterholes," said John Kappelman, a UT anthropology and earth and planetary sciences professor and lead author of the study. "Seasonal rivers thus functioned as 'pumps' that siphoned populations out along the channels from one waterhole to another, potentially driving the most recent out-of-Africa dispersal.

The humans who lived at Shinfa-Metema 1 are unlikely to have been members of the group that left Africa. However, the behavioral flexibility that helped them adapt to challenging climatic conditions such as the Toba supereruption was probably a key trait of Middle Stone Age humans that allowed our species to ultimately disperse from Africa and expand across the globe.

The people living in the Shinfa-Metema 1 site hunted a variety of terrestrial animals, from antelope to monkey, as attested to by cut marks on the bones, and apparently cooked their meals as shown by evidence of controlled fire at the site. The most distinctive stone tools are small, symmetrical triangular points. Analyses show that the points are most likely arrowheads that, at 74,000 years in age, represent the oldest evidence of archery.

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Did neanderthals use glue? Researchers find evidence that sticks

Neanderthals created stone tools held together by a multi-component adhesive, a team of scientists has discovered. Its findings, which are the earliest evidence of a complex adhesive in Europe, suggest these predecessors to modern humans had a higher level of cognition and cultural development than previously thought.

The work, reported in the journal Science Advances, included researchers from New York University, the University of Tübingen, and the National Museums in Berlin.

"These astonishingly well-preserved tools showcase a technical solution broadly similar to examples of tools made by early modern humans in Africa, but the exact recipe reflects a Neanderthal 'spin,' which is the production of grips for handheld tools," says Radu Iovita, an associate professor at New York University's Center for the Study of Human Origins.

The research team, led by Patrick Schmidt from the University of Tübingen's Early Prehistory and Quaternary Ecology section and Ewa Dutkiewicz from the Museum of Prehistory and Early History at the National Museums in Berlin, re-examined previous finds from Le Moustier, an archaeological site in France that was discovered in the early 20th century.

The stone tools from Le Moustier -- used by Neanderthals during the Middle Palaeolithic period of the Mousterian between 120,000 and 40,000 years ago -- are kept in the collection of Berlin's Museum of Prehistory and Early History and had not previously been examined in detail.

The tools were rediscovered during an internal review of the collection and their scientific value was recognized.

"The items had been individually wrapped and untouched since the 1960s," says Dutkiewicz.

"As a result, the adhering remains of organic substances were very well preserved."

The researchers discovered traces of a mixture of ochre and bitumen on several stone tools, such as scrapers, flakes, and blades.

Ochre is a naturally occurring earth pigment; bitumen is a component of asphalt and can be produced from crude oil, but also occurs naturally in the soil.

"We were surprised that the ochre content was more than 50 percent," says Schmidt.

"This is because air-dried bitumen can be used unaltered as an adhesive, but loses its adhesive properties when such large proportions of ochre are added."

He and his team examined these materials in tensile tests -- used to determine strength -- and other measures.

"It was different when we used liquid bitumen, which is not really suitable for gluing. If 55 percent ochre is added, a malleable mass is formed," Schmidt says.

The mixture was just sticky enough for a stone tool to remain stuck in it, but without adhering to hands, making it suitable material for a handle.

In fact, a microscopic examination of the use-wear traces on these stone tools revealed that the adhesives on the tools from Le Moustier were used in this way.

"The tools showed two kinds of microscopic wear: one is the typical polish on the sharp edges that is generally caused by working other materials," explains Iovita, who conducted this analysis.

"The other is a bright polish distributed all over the presumed hand-held part, but not elsewhere, which we interpreted as the results of abrasion from the ochre due to movement of the tool within the grip."

The use of adhesives with several components, including various sticky substances such as tree resins and ochre, was previously known from early modern humans, Homo sapiens, in Africa but not from earlier Neanderthals in Europe.

Overall, the development of adhesives and their use in the manufacture of tools is considered to be some of the best material evidence of the cultural evolution and cognitive abilities of early humans.

"Compound adhesives are considered to be among the first expressions of the modern cognitive processes that are still active today," says Schmidt.

In the Le Moustier region, ochre and bitumen had to be collected from distant locations, which meant a great deal of effort, planning, and a targeted approach, the authors note.

"Taking into account the overall context of the finds, we assume that this adhesive material was made by Neanderthals," concludes Dutkiewicz.

"What our study shows is that early Homo sapiens in Africa and Neanderthals in Europe had similar thought patterns," adds Schmidt.

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Neanderthals and humans lived side by side in Northern Europe 45,000 years ago

A genetic analysis of bone fragments unearthed at an archaeological site in central Germany shows conclusively that modern humans -- Homo sapiens -- had already reached Northern Europe 45,000 years ago, overlapping with Neanderthals for several thousand years before the latter went extinct.

The findings establish that the site near Ranis, Germany, which is known for its finely flaked, leaf-shaped stone tool blades, is among the oldest confirmed sites of modern human Stone Age culture in north central and northwestern Europe.

The evidence that Homo sapiens and Homo neanderthalensis lived side by side is consistent with genomic evidence that the two species occasionally interbred. It also feeds the suspicion that the invasion of Europe and Asia by modern humans some 50,000 years ago helped drive Neanderthals, which had occupied the area for more than 500,000 years, to extinction.

The genetic analysis, along with an archaeological and isotopic analysis and radiocarbon dating of the Ranis site, are detailed in a trio of papers appearing today in the journals Nature and Nature Ecology and Evolution.

The stone blades at Ranis, referred to as leaf points, are similar to stone tools found at several sites in Moravia, Poland, Germany and the United Kingdom. These tools that are thought to have been produced by the same culture, referred to as the Lincombian-Ranisian-Jerzmanowician (LRJ) culture or technocomplex. Because of previous dating, the Ranis site was known to be 40,000 years old or older, but without recognizable bones to indicate who made the tools, it was unclear whether they were the product of Neanderthals or Homo sapiens.

The new findings demonstrate that "Homo sapiens made this technology, and that Homo sapiens were this far north at this time period, which is 45,000 years ago," said Elena Zavala, one of four first authors of the Nature paper and a Miller Research Fellow at the University of California, Berkeley. "So these are among the earliest Homo sapiens in Europe."

Zavala was a Ph.D. student at the Max Planck Institute for Evolutionary Anthropology (MPI-EVA) in Leipzig in 2018 when she first began working on the project, which was a major effort spearheaded by Jean-Jacque Hublin, former director of the institute and a professor at the Collège de France in Paris.

"The Ranis cave site provides evidence for the first dispersal of Homo sapiens across the higher latitudes of Europe. It turns out that stone artifacts that were thought to be produced by Neanderthals were, in fact, part of the early Homo sapiens toolkit," Hublin said. "This fundamentally changes our previous knowledge about the period: Homo sapiens reached northwestern Europe long before Neanderthal disappearance in southwestern Europe."

Bones from maternal relatives?

Zavala conducted the genetic analysis of hominid bone fragments from the new and deeper excavations at Ranis between 2016 and 2022 and from earlier excavations in the 1930s. Because the DNA in ancient bones is highly fragmented, she employed special techniques to isolate and sequence the DNA, all of it mitochondrial DNA (mtDNA) that is inherited solely from the mother.

"We confirmed that the skeletal fragments belonged to Homo sapiens. Interestingly, several fragments shared the same mitochondrial DNA sequences -- even fragments from different excavations," she said. "This indicates that the fragments belonged to the same individual or their maternal relatives, linking these new finds with the ones from decades ago."

The bone fragments were initially identified as human through analysis of bone proteins -- a field called paleoproteomics -- by another first author, Dorothea Mylopotamitaki, a doctoral student at the Collège de France and fomerly of MPI-EVA.

By comparing the Ranis mitochondrial DNA sequences with mtDNA sequences obtained from human remains at other paleolithic sites in Europe, Zavala was able to construct a family tree of early Homo sapiens across Europe. All but one of the 13 Ranis fragments were quite similar to one another and, surprisingly, resembled mtDNA from the 43,000-year-old skull of a woman discovered in a cave at Zlatý k?? in the Czech Republic. The lone standout grouped with an individual from Italy.

"That raises some questions: Was this a single population? What could be the relationship here?" Zavala said. "But with mitochondrial DNA, that's only one side of the history. It's only the maternal side. We would need to have nuclear DNA to be able to start looking into this."

A transitional site between Middle and Upper Paleolithic

Zavala specializes in the analysis of DNA found in long-buried bones, on bone tools and in sediment. Her search through sediment from various levels of the Ranis excavation turned up DNA from a broad array of mammals, but none from hominids. The analysis, combined with morphological, isotopic and proteomic analysis of bone fragments, paints a picture of the environment at that time and of the diet of both humans and animals that occupied the cave over the millennia.

The presence of reindeer, cave bear, woolly rhinoceros and horse bones, for example, indicated cold climatic conditions typical of steppe tundra and similar to conditions in Siberia and northern Scandinavia today, and a human diet based on large terrestrial animals. The researchers concluded that the cave was used primarily by hibernating cave bears and denning hyenas, with only periodic human presence.

"This lower-density archaeological signature matches other Lincombian-Ranisian-Jerzmanowician sites and is best explained by expedient visits of short duration by small, mobile groups of pioneer H. sapiens," according to one of the papers published in Nature Ecology and Evolution.

"This shows that even these earlier groups of Homo sapiens dispersing across Eurasia already had some capacity to adapt to such harsh climatic conditions," said Sarah Pederzani, a postdoctoral fellow at the University of La Laguna in Spain, who led the paleoclimate study of the site. "Until recently, it was thought that resilience to cold-climate conditions did not appear until several thousand years later, so this is a fascinating and surprising result."

The Ranis site, called Ilsenhöhle and located at the base of a castle, was initially excavated mainly between 1932 and 1938. The leaf points found there were eventually assigned to the final years of the Middle Paleolithic period -- between about 300,000 and 30,000 years ago -- or the beginning of the Upper Paleolithic, which begins around 50,000 years ago.

Because of the importance of the Ranis site for understanding the LRJ technocomplex and the transition from the Neanderthal-associated late Middle Paleolithic to the modern human Upper Paleolithic in central Europe, Hublin and his team decided to reexcavate the site using modern tools of archaeology.

The new excavations extended to bedrock, about 8 meters below the surface, and involved removing a rock -- likely fallen from the cave ceiling -- that had halted the previous excavation. Here, Hublin's team uncovered chips from flint tools and a quartzite flake consistent with the LRJ technocomplex. Subsequent proteomic analysis of thousands of recovered bone chips confirmed that four were from hominids. Of bone chips uncovered during the 1930s excavations, nine were from hominids.

Zavala's DNA analysis confirmed that all 13 bone fragments came from Homo sapiens.

A revised settlement history of Northern Europe

The team also carried out radiocarbon dating of human and animal bones from different layers of the site to reconstruct the site's chronology, focusing on bones with traces of human modifications on their surfaces, which links their dates to human presence in the cave.

"We found very good agreement between the radiocarbon dates from the Homo sapiens bones from both excavation collections and with modified animal bones from the LRJ layers of the new excavation, making a very strong link between the human remains and LRJ. The evidence suggests that Homo sapiens were sporadically occupying the site from as early as 47,500 years ago," said another first author, Helen Fewlass, a former Max Planck researcher who is now a European Molecular Biology Organization (EMBO) Postdoctoral Fellow at the Francis Crick Institute in London.

"The results from the Ilsenhöhle in Ranis fundamentally changed our ideas about the chronology and settlement history of Europe north of the Alps," added Tim Schüler of the Thuringian State Office for the Preservation of Historical Monuments and Archaeology in Weimar, Germany.

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Paleolithic humans may have understood the properties of rocks for making stone tools

A research group led by the Nagoya University Museum and Graduate School of Environmental Studies in Japan has clarified differences in the physical characteristics of rocks used by early humans during the Paleolithic. They found that humans selected rock for a variety of reasons and not just because of how easy it was to break off. This suggests that early humans had the technical skill to discern the best rock for the tool. The researchers published the results in the Journal of Paleolithic Archaeology.

As Homo sapiens moved from Africa to Eurasia, they used stone tools made of rocks, such as obsidian and flint, to cut, slice, and craft ranged weapons.

Because of the significant role they played in their culture, understanding how early humans made stone tools is important to archaeologists.

Since the geographic expansion of Homo sapiens in Eurasia started in the Middle East, archaeologists Eiki Suga and Seiji Kadowaki from Nagoya University focused on the prehistoric sites belonging to three chronological periods in the Jebel Qalkha area, southern Jordan.

The team analyzed flint nodules in the outcrops that were exploited during the Middle and Upper Paleolithic (70,000 to 30,000 years ago).

They believe Paleolithic humans understood which rocks were appropriate for making tools and, therefore, intentionally searched for them.

According to their hypothesis, Paleolithic humans intentionally searched for flint that was translucent and smooth, as it could be easily broken off the rock face and shaped into sharp edges.

The group used a Schmidt Hammer and a Rockwell Hardness Device to test the mechanical properties of the rocks.

The Schmidt Hammer measures the elastic behavior of a material after the hammer strikes it, which tells researchers its rebound hardness.

The Rockwell hardness device presses a diamond indenter on the rock surface to test its strength.

At first, as Suga and Kadowaki expected, fine-grained flint was found to require less force to fracture than medium-grained flint.

This would have made the fine-grained flint more attractive in producing small stone tools.

Indeed, many stone tools from the Early Upper Paleolithic (40,000 to 30,000 years ago) contain fine-grained flint.

However, an earlier study by the same team found that during the Late Middle Paleolithic and the Initial Upper Paleolithic (70,000 to 40,000 years ago), medium-grained flint was more commonly used in stone tools than fine-grained flint.

But if fine-grained flint was so easy to use, why did our ancestors not make all their tools from it?

On further investigation, the researchers found that much of the fine-grained flint in the area suffered from abundant internal fractures caused by geological activities, which would have made it unsuitable for large stone tools, such as Levallois products and robust blades.

Therefore, it seems that Paleolithic humans selected the medium-grained flint for large tools, even though it was a tough material to modify into tools, as it was more likely to last longer.

This offers a fascinating insight into our ancestors' behavior, as they selected flint based on many factors other than just how easy it was to fracture and could discern the most suitable rock to use to make stone tools.

Suga is enthusiastic about the findings, which suggest the complexity of our ancestors' behaviour.

"This study illustrates that the Paleolithic humans changed their choice of raw material to suit their stone tool morphologies and production techniques," he said.

"We believe that these prehistoric humans had a sensory understanding of the characteristics of the rocks and intentionally selected the stone material to be used according to the form and production technique of the desired stone tools. This intentional selection of the lithic raw material may have been an important component of the production of stone tools. This may show some aspect of flexible technological behavior adapted to the situation."

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Archaeologists discover world's oldest wooden structure

Half a million years ago, earlier than was previously thought possible, humans were building structures made of wood, according to new research by a team from the University of Liverpool and Aberystwyth University.

The research, published in the journal Nature, reports on the excavation of well-preserved wood at the archaeological site of Kalambo Falls, Zambia, dating back at least 476,000 years and predating the evolution of our own species, Homo sapiens.

Expert analysis of stone tool cut-marks on the wood show that these early humans shaped and joined two large logs to make a structure, probably the foundation of a platform or part of a dwelling.

This is the earliest evidence from anywhere in the world of the deliberate crafting of logs to fit together. Until now, evidence for the human use of wood was limited to its use for making fire, digging sticks and spears.

Wood is rarely found in such ancient sites as it usually rots and disappears, but at Kalambo Falls permanently high water levels preserved the wood.

This discovery challenges the prevailing view that Stone Age humans were nomadic. At Kalambo Falls these humans not only had a perennial source of water, but the forest around them provided enough food to enable them to settle and make structures.

Professor Larry Barham, from the University of Liverpool's Department of Archaeology, Classics and Egyptology, who leads the 'Deep Roots of Humanity' research project said:

"This find has changed how I think about our early ancestors. Forget the label 'Stone Age,' look at what these people were doing: they made something new, and large, from wood. They used their intelligence, imagination, and skills to create something they'd never seen before, something that had never previously existed."

"They transformed their surroundings to make life easier, even if it was only by making a platform to sit on by the river to do their daily chores. These folks were more like us than we thought."

The specialist dating of the finds was undertaken by experts at Aberystwyth University.

They used new luminescence dating techniques, which reveal the last time minerals in the sand surrounding the finds were exposed to sunlight, to determine their age.

Professor Geoff Duller from Aberystwyth University said:

"At this great age, putting a date on finds is very challenging and we used luminescence dating to do this. These new dating methods have far reaching implications -- allowing us to date much further back in time, to piece together sites that give us a glimpse into human evolution. The site at Kalambo Falls had been excavated back in the 1960s when similar pieces of wood were recovered, but they were unable to date them, so the true significance of the site was unclear until now."

The site of Kalambo Falls on the Kalambo River lies above a 235 metres (772 foot) waterfall on the border of Zambia with the Rukwa Region of Tanzania at the edge of Lake Tanganyika. The area is on a 'tentative' list from UNESCO for becoming a World Heritage site because of its archaeological significance.

Professor Duller added:

"Our research proves that this site is much older than previously thought, so its archaeological significance is now even greater. It adds more weight to the argument that it should be a United Nations World Heritage Site."

This research forms part of the pioneering 'Deep Roots of Humanity' project, an investigation into how human technology developed in the Stone Age. The project is funded by the UK's Arts and Humanities Research Council and involved teams from Zambia's National Heritage Conservation Commission, Livingstone Museum, Moto Moto Museum and the National Museum, Lusaka.

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Surprising similarities in stone tools of early humans and monkeys

Researchers from the Max Planck Institute for Evolutionary Anthropology have discovered artefacts produced by old world monkeys in Thailand that resemble stone tools, which historically have been identified as intentionally made by early hominins. Until now, sharp-edged stone tools were thought to represent the onset of intentional stone tool production, one of the defining and unique characteristics of hominin evolution. This new study challenges long held beliefs about the origins of intentional tool production in our own lineage.

The research is based on new analyses of stone tools used by long-tailed macaques in the Phang Nga National Park in Thailand. These monkeys use stone tools to crack open hard-shelled nuts. In that process, the monkeys often break their hammerstones and anvils. The resulting assemblage of broken stones is substantial and widespread across the landscape. Moreover, many of these artefacts bear all of the same characteristics that are commonly used to identify intentionally made stone tools in some of the earliest archaeological sites in East Africa.

"The ability to intentionally make sharp stone flakes is seen as a crucial point in the evolution of hominins, and understanding how and when this occurred is a huge question that is typically investigated through the study of past artefacts and fossils. Our study shows that stone tool production is not unique to humans and our ancestors," says lead author Tomos Proffitt, a researcher at the Max Planck Institute for Evolutionary Anthropology. "The fact that these macaques use stone tools to process nuts is not surprising, as they also use tools to gain access to various shellfish as well. What is interesting is that, in doing so they accidently produce a substantial archaeological record of their own that is partly indistinguishable from some hominin artefacts."

New insights into the evolution of stone tool technology

By comparing the accidentally produced stone fragments made by the macaques with those from some of the earliest archaeological sites, the researchers were able to show that many of the artefacts produced by monkeys fall within the range of those commonly associated with early hominins. Co-lead author Jonathan Reeves highlights: "The fact that these artifacts can be produced through nut cracking has implications for the range of behaviours we associate with sharp edged flakes in the archaeological record.."

The newly discovered macaque stone tools offer new insights into how the first technology might have started in our earliest ancestors and that its origin may have been linked to similar nut cracking behaviour which could be substantially older than the current earliest archaeological record. "Cracking nuts using stone hammers and anvils, similar to what some primates do today, has been suggested by some as a possible precursor to intentional stone tool production. This study, along with previous ones published by our group, opens the door to being able to identify such an archaeological signature in the future," says Lydia Luncz, senior author of the study and head of the Technological Primates Research Group at the Max Planck Institute for Evolutionary Anthropology. "This discovery shows how living primates can help researchers investigate the origin and evolution of tool use in our own lineage."

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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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Ancient stone tools from China provide earliest evidence of rice harvesting

A new Dartmouth-led study analyzing stone tools from southern China provides the earliest evidence of rice harvesting, dating to as early as 10,000 years ago. The researchers identified two methods of harvesting rice, which helped initiate rice domestication. The results are published in PLOS ONE.

Wild rice is different from domesticated rice in that wild rice naturally sheds ripe seeds, shattering them to the ground when they mature, while cultivated rice seeds stay on the plants when they mature.

To harvest rice, some sort of tools would have been needed. In harvesting rice with tools, early rice cultivators were selecting the seeds that stay on the plants, so gradually the proportion of seeds that remain increased, resulting in domestication.

"For quite a long time, one of the puzzles has been that harvesting tools have not been found in southern China from the early Neolithic period or New Stone Age (10,000 -- 7,000 Before Present) -- the time period when we know rice began to be domesticated," says lead author Jiajing Wang, an assistant professor of anthropology at Dartmouth. "However, when archaeologists were working at several early Neolithic sites in the Lower Yangtze River Valley, they found a lot of small pieces of stone, which had sharp edges that could have been used for harvesting plants."

"Our hypothesis was that maybe some of those small stone pieces were rice harvesting tools, which is what our results show."

In the Lower Yangtze River Valley, the two earliest Neolithic culture groups were the Shangshan and Kuahuqiao.

The researchers examined 52 flaked stone tools from the Shangshan and Hehuashan sites, the latter of which was occupied by Shangshan and Kuahuqiao cultures.

The stone flakes are rough in appearance and are not finely made but have sharp edges. On average, the flaked tools are small enough to be held by one hand and measured approximately 1.7 inches in width and length.

To determine if the stone flakes were used for harvesting rice, the team conducted use-wear and phytolith residue analyses.

For the use-wear analysis, micro-scratches on the tools' surfaces were examined under a microscope to determine how the stones were used. The results showed that 30 flakes have use-wear patterns similar to those produced by harvesting siliceous (silica-rich) plants, likely including rice.

Fine striations, high polish, and rounded edges distinguished the tools that were used for cutting plants from those that were used for processing hard materials, cutting animal tissues, and scraping wood.

Through the phytolith residue analysis, the researchers analyzed the microscopic residue left on the stone flakes known as "phytoliths" or silica skeleton of plants. They found that 28 of the tools contained rice phytoliths.

"What's interesting about rice phytoliths is that rice husk and leaves produce different kinds of phytolith, which enabled us to determine how the rice was harvested," says Wang.

The findings from the use-wear and phytolith analyses illustrated that two types of rice harvesting methods were used -- "finger-knife" and "sickle" techniques. Both methods are still used in Asia today.

The stone flakes from the early phase (10,000 -- 8,200 BP) showed that rice was largely harvested using the finger-knife method in which the panicles at the top of the rice plant are reaped. The results showed that the tools used for finger-knife harvesting had striations that were mainly perpendicular or diagonal to the edge of the stone flake, which suggests a cutting or scraping motion, and contained phytoliths from seeds or rice husk phytoliths, indicating that the rice was harvested from the top of the plant.

"A rice plant contains numerous panicles that mature at different times, so the finger-knife harvesting technique is especially useful when rice domestication was in the early stage," says Wang.

The stone flakes however, from the later phase (8,000 -- 7,000 BP) had more evidence of sickle harvesting in which the lower part of the plant was harvested. These tools had striations that were predominantly parallel to the tool's edge, reflecting that a slicing motion had likely been used.

"Sickle harvesting was more widely used when rice became more domesticated, and more ripe seeds stayed on the plant," says Wang. "Since you are harvesting the entire plant at the same time, the rice leaves and stems could also be used for fuel, building materials, and other purposes, making this a much more effective harvesting method."

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Chimpanzee stone tool diversity

During fieldwork aimed at documenting the stone tool use of a group of wild chimpanzees in the Taï Forest in Cote d'Ivoire in early 2022, the researchers identified and 3D scanned a variety of stone tools used to crack different nut species.

It has long been shown that various chimpanzee groups possess different tool use cultures involving wooden and stone tools, however, only some groups in West Africa use stone tools to crack open nuts. By comparing the 3D models of different stone tools used by chimpanzees in the Taï Forest to those from another group in Guinea, the researchers showed that there exist notable differences between the two groups in terms of their material culture.

The study shows that this particular group of chimpanzees in Guinea uses stone hammers varying in the type of stone and sizes, and very large stone anvils, sometimes greater than one meter in length. These durable stone tools are widespread across the landscape; preserve different levels of damage related to their use and represent a lasting record of chimpanzee behaviours.

Stone tools used for nut cracking can differ between chimpanzee groups

This study highlights the fact that, although several groups of chimpanzees practice nut cracking, the tools they use can differ significantly from one another, potentially leading to group specific material signatures. These differences are driven by a combination of stone choice, stone availability, and the nut species eaten.

Previous research has shown, that by using stone tools, some groups of chimpanzees develop their own archaeological record dating to at least 4,300 years ago. "The ability to identify regional differences in stone tool material culture in primates opens up a range of possibilities for future primate archaeological studies," says Tomos Proffitt from the Max Planck Institute of Evolutionary Anthropology, who led the research.

It has been hypothesised that a simple technology, like nut cracking, was a precursor to more complex stone technologies during the early stages of our own evolution more than three million years ago. Proffitt continues, "by understanding what this simple stone tool technology looks like, and how it varies between groups, we can start to understand how to better identify this signature in the earliest hominin archaeological record."

From Science Daily

Collectors in the prehistoric world recycled old stone tools to preserve the memory of their ancestors

A first-of-its-kind study at Tel Aviv University asks what drove prehistoric humans to collect and recycle flint tools that had been made, used, and discarded by their predecessors. After examining flint tools from one layer at the 500,000-year-old prehistoric site of Revadim in the south of Israel's Coastal Plain, the researchers propose a novel explanation: prehistoric humans, just like us, were collectors by nature and culture. The study suggests that they had an emotional urge to collect old human-made artefacts, mostly as a means for preserving the memory of their ancestors and maintaining their connectedness with place and time.

The study was led by PhD student Bar Efrati and Prof. Ran Barkai of the Jacob M. Alkow Department of Archaeology and Ancient Near Eastern Cultures at TAU's Entin Faculty of Humanities, in collaboration with Dr. Flavia Venditti from the University of Tubingen in Germany and Prof. Stella Nunziante Cesaro from the Sapienza University of Rome, Italy. The paper appeared in the journal Scientific Reports, published by Nature.

Bar Efrati explains that stone tools with two lifecycles have been found at prehistoric sites all over the world, but the phenomenon has never been thoroughly investigated. In the current study the researchers focused on a specific layer at Revadim -- a large, open-air, multi-layered site in the south of Israel's Coastal Plain, dated to about 500,000 years ago. The rich findings at Revadim suggest that this was a popular spot in the prehistoric landscape, revisited over and over again by early humans drawn by an abundance of wildlife, including elephants. Moreover, the area is rich with good-quality flint, and most tools found at Revadim were in fact made of fresh flint.

Bar Efrati: "The big question is: Why did they do it? Why did prehistoric humans collect and recycle actual tools originally produced, used, and discarded by their predecessors, many years earlier? Scarcity of raw materials was clearly not the reason at Revadim, where good-quality flint is easy to come by. Nor was the motivation merely functional, since the recycled tools were neither unusual in form nor uniquely suitable for any specific use."

The key to identifying the recycled tools and understanding their history is the patina -- a chemical coating which forms on flint when it is exposed to the elements for a long period of time. Thus, a discarded flint tool that lay on the ground for decades or centuries accumulated an easily identifiable layer of patina, which is different in both color and texture from the scars of a second cycle of processing that exposed the original color and texture of flint.

In the current study, 49 flint tools with two lifecycles were examined. Produced and used in their first lifecycle, these tools were abandoned, and years later, after accumulating a layer of patina, they were collected, reworked, and used again. The individuals who recycled each tool removed the patina, exposing fresh flint, and shaped a new active edge. Both edges, the old and the new, were examined by the researchers under two kinds of microscopes, and via various chemical analyses, in search of use-wear marks and/or organic residues. In the case of 28 tools, use-wear marks were found on the old and/or new edges, and in 13 tools, organic residues were detected, evidence of contact with animal bones or fat.

Surprisingly, the tools had been used for very different purposes in their two lifecycles -- the older edges primarily for cutting, and the newer edges for scraping (processing soft materials like leather and bone). Another baffling discovery: in their second lifecycle the tools were reshaped in a very specific and minimal manner, preserving the original form of the tool, including its patina, and only slightly modifying the active edge.

Read more at Science Daily

Orangutans instinctively use hammers to strike and sharp stones to cut, study finds

Untrained, captive orangutans can complete two major steps in the sequence of stone tool use: striking rocks together and cutting using a sharp stone, according to a study by Alba Motes-Rodrigo at the University of Tübingen in Germany and colleagues, publishing February 16 in the open-access journal PLOS ONE.

The researchers tested tool making and use in two captive male orangutans (Pongo pygmaeus) at Kristiansand Zoo in Norway. Neither had previously been trained or exposed to demonstrations of the target behaviors. Each orangutan was provided with a concrete hammer, a prepared stone core, and two baited puzzle boxes requiring them to cut through a rope or a silicon skin in order to access a food reward. Both orangutans spontaneously hit the hammer against the walls and floor of their enclosure, but neither directed strikes towards the stone core. In a second experiment, the orangutans were also given a human-made sharp flint flake, which one orangutan used to cut the silicon skin, solving the puzzle. This is the first demonstration of cutting behavior in untrained, unenculturated orangutans.

To then investigate whether apes could learn the remaining steps from observing others, the researchers demonstrated how to strike the core to create a flint flake to three female orangutans at Twycross Zoo in the UK. After these demonstrations, one female went on to use the hammer to hit the core, directing the blows towards the edge as demonstrated.

This study is the first to report spontaneous stone tool use without close direction in orangutans that have not been enculturated by humans. The authors say their observations suggest that two major prerequisites for the emergence of stone tool use -- striking with stone hammers and recognizing sharp stones as cutting tools -- may have existed in our last common ancestor with orangutans, 13 million years ago.

The authors add: "Our study is the first to report that untrained orangutans can spontaneously use sharp stones as cutting tools. We also found that they readily engage in lithic percussion and that this activity occasionally leads to the detachment of sharp stone pieces."

From Science Daily

Roman-era mixers and millstones made with geology in mind

A study on stone tools from an outpost of the Roman Empire has found that for ancient bakers and millers, having the right tools was a matter of geology.

A team of geoscientists and archaeologists made the discovery by analyzing samples of the tools at a University of Texas at Austin geology lab, finding that dough mixing vats and millstones from Roman-era ruins of Volubilis, a city in Morocco, were made from specific rock types that probably improved each tool's function.

Furthermore, the researchers determined that the stones were sourced locally, a discovery that challenges a theory that some millstones had been imported from afar. It also means that the craftspeople who made the tools may have received input directly from the workers who used them.

"It is interesting because it is a very local source and seemingly from one source," said Jared Benton, a study co-author and an assistant professor at Old Dominion University who studies trade between Roman-era workshops. "One wonders if there's not a group of bakers that are coming together and saying let's buy our stuff from this one quarry, or maybe there's just one guy who [sells the stones], and that's it."

The results were published in the Journal of Archaeological Science: Reports.

Derek Weller, a postdoctoral researcher at the University of Tokyo's Earthquake Research Institute, led the study. Additional co-authors include Omero "Phil" Orlandini, research associate and manager of the Electron Microbeam Laboratory at the UT Jackson School of Geosciences; Lauren LoBue and Scott Culotta, both undergraduates at the Jackson School; and Christy Schirmer, a graduate student in UT's Department of Classics.

The study got its start in early 2020, when Schirmer showed up at Orlandini's lab with a box of rocks. They were pieces of the stone tools that she and Benton had collected from the tools in Volubilis -- and they were curious about where learning more about their geological makeup could lead them.

"They sort of look the same when they're in tool form, but as soon as we started looking, it was clear that they were completely different," Orlandini said.

Olandini got LoBue and Culotta on the case. The undergraduates put all 16 samples through a detailed scientific workup to determine their composition at the geochemical level.

Their research revealed a rock type for each tool type. Grain millstones were made from vesicular basalts (a volcanic stone full of sharp-edged pores); olive mills were made from clastic, fossiliferous limestone (a limestone containing fragments of other rocks and small fossil shells); and dough mixers were made from limestone with no clastic material or fossils.

The study notes how the rocks' attributes relate to each tool's function. For example, the pores in the basalt may have helped provide fresh edges that could help grind wheat into flour as the stone was worn down.

Weller also used the geochemical data to determine that all the stones came from sources near Volubilis. Limestone is plentiful in the region, and two limestone quarries were already known to be active during the Roman era near Volubilis. But archaeologists previously thought the basalt -- which Weller found came from the nearby Middle Atlas Mountains -- was imported from Italy.

In addition, the research found that each rock type came from a single location rather than sourced from different places around Volubilis. Benton said this suggests that a single supplier for each stone type might have been meeting all demand in the city and getting input from local people.

Elizabeth Fentress, an archaeologist specializing in Roman settlements in North Africa, said that the study is a great example of collaborative research.

Read more at Science Daily

Neanderthal and early modern human stone tool culture co-existed for over 100,000 years

 Research from the University of Kent's School of Anthropology and Conservation has discovered that one of the earliest stone tool cultures, known as the Acheulean, likely persisted for tens of thousands of years longer than previously thought.

The Acheulean was estimated to have died out around 200,000 years ago but the new findings suggest it may have persisted for much longer, creating over 100,000 years of overlap with more advanced technologies produced by Neanderthals and early modern humans.

The research team, led by Dr Alastair Key (Kent) alongside Dr David Roberts (Kent) and Dr Ivan Jaric (Biology Centre of the Czech Academy of Sciences), made the discovery whilst studying stone tool records from different regions across the world. Using statistical techniques new to archaeological science, the archaeologists and conservation experts were able to reconstruct the end of the Acheulean period and re-map the archaeological record.

Previously, a more rapid shift between the earlier Acheulean stone tool designs often associated with Homo heidelbergensis -- the common ancestor of modern humans and Neanderthals -- and more advanced 'Levallois' technologies created by early modern humans and Neanderthals, was assumed. However, the study has shed new light on the transition between these two technologies, suggesting substantial overlap between the two.

Acheulean stone tool technologies are the longest-lived cultural tradition practiced by early humans. Originating in East Africa 1.75 million years ago, handaxes and cleavers -- the stone tool types which characterise the period -- went on to be used across Africa, Europe and Asia by several different species of early human. Prior to this discovery, it was widely assumed that the Acheulean period ended between 300-150,000 year ago. However, the record was lacking in specific dates, and the timing of its demise has been heavily debated. The Kent and Czech team discovered that the tradition likely ended at different times around the world, varying from as early as 170,000 years ago in Sub-Saharan Africa through to as late as 57,000 years ago in Asia.

To understand when the Acheulean ended, the team collected information on different archaeological sites from around the world to find the latest known stone tool assemblages. A statistical technique known as optimal linear estimation -- commonly used in conservation studies to estimate species extinctions -- was used to predict how much longer the stone tool tradition continued after the most recent known sites. In effect, the technique was able to model the portion of the archaeological record yet to be discovered.

Dr Alastair Key, a Palaeolithic Archaeologist and the lead author of the study, said: "The earliest archaeological record will always be an incomplete picture of early human behaviour, so we know that the youngest known Acheulean sites are unlikely to actually represent the final instances of these technologies being produced. By allowing us to reconstruct these missing portions of the archaeological record, this technique not only gives us a more accurate understanding of when the tradition ended, but it gives us an indication of where we can expect to find new archaeological discoveries in the future."

Dr Roberts added: "This technique was originally developed by myself and a colleague to date extinctions, as the last sighting of a species is unlikely to be the date when it actually became extinct. It is exciting to see it applied in a new context."

Read more at Science Daily

Neanderthals and Homo sapiens used identical Nubian technology

 Long held in a private collection, the newly analysed tooth of an approximately 9-year-old Neanderthal child marks the hominin's southernmost known range. Analysis of the associated archaeological assemblage suggests Neanderthals used Nubian Levallois technology, previously thought to be restricted to Homo sapiens.

With a high concentration of cave sites harbouring evidence of past populations and their behaviour, the Levant is a major centre for human origins research. For over a century, archaeological excavations in the Levant have produced human fossils and stone tool assemblages that reveal landscapes inhabited by both Neanderthals and Homo sapiens, making this region a potential mixing ground between populations. Distinguishing these populations by stone tool assemblages alone is difficult, but one technology, the distinct Nubian Levallois method, is argued to have been produced only by Homo sapiens.

In a new study published in Scientific Reports, researchers from the Max Planck Institute for the Science of Human History teamed up with international partners to re-examine the fossil and archaeological record of Shukbah Cave. Their findings extend the southernmost known range of Neanderthals and suggest that our now-extinct relatives made use of a technology previously argued to be a trademark of modern humans. This study marks the first time the lone human tooth from the site has been studied in detail, in combination with a major comparative study examining the stone tool assemblage.

"Sites where hominin fossils are directly associated with stone tool assemblages remain a rarity -- but the study of both fossils and tools is critical for understanding hominin occupations of Shukbah Cave and the larger region," says lead author Dr Jimbob Blinkhorn, formerly of Royal Holloway, University of London and now with the Pan-African Evolution Research Group (Max Planck Institute for the Science of Human History).

Shukbah Cave was first excavated in the spring of 1928 by Dorothy Garrod, who reported a rich assemblage of animal bones and Mousterian-style stone tools cemented in breccia deposits, often concentrated in well-marked hearths. She also identified a large, unique human molar. However, the specimen was kept in a private collection for most of the 20th century, prohibiting comparative studies using modern methods. The recent re-identification of the tooth at the Natural History Museum in London has led to new detailed work on the Shukbah collections.

"Professor Garrod immediately saw how distinctive this tooth was. We've examined the size, shape and both the external and internal 3D structure of the tooth, and compared that to Holocene and Pleistocene Homo sapiens and Neanderthal specimens. This has enabled us to clearly characterise the tooth as belonging to an approximately 9 year old Neanderthal child," says Dr. Clément Zanolli, from Université de Bordeaux. "Shukbah marks the southernmost extent of the Neanderthal range known to date," adds Zanolli.

Although Homo sapiens and Neanderthals shared the use of a wide suite of stone tool technologies, Nubian Levallois technology has recently been argued to have been exclusively used by Homo sapiens. The argument has been made particularly in southwest Asia, where Nubian Levallois tools have been used to track human dispersals in the absence of fossils.

"Illustrations of the stone tool collections from Shukbah hinted at the presence of Nubian Levallois technology so we revisited the collections to investigate further. In the end, we identified many more artefacts produced using the Nubian Levallois methods than we had anticipated," says Blinkhorn. "This is the first time they've been found in direct association with Neanderthal fossils, which suggests we can't make a simple link between this technology and Homo sapiens."

"Southwest Asia is a dynamic region in terms of hominin demography, behaviour and environmental change, and may be particularly important to examine interactions between Neanderthals and Homo sapiens," adds Prof Simon Blockley, of Royal Holloway, University of London. "This study highlights the geographic range of Neanderthal populations and their behavioural flexibility, but also issues a timely note of caution that there are no straightforward links between particular hominins and specific stone tool technologies."

Read more at Science Daily

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

 

Illustration depicting prehistoric group of people

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

Read more at Science Daily

The oldest Neanderthal DNA of Central-Eastern Europe

 Around 100,000 years ago, the climate worsened abruptly and the environment of Central-Eastern Europe shifted from forested to open steppe/taiga habitat, promoting the dispersal of wooly mammoth, wooly rhino and other cold adapted species from the Arctic. Neanderthals living in these territories suffered severe demographic contractions due to the new ecological conditions and only returned to the areas above 48° N latitude during climatic ameliorations. However, in spite of the discontinuous settlement, specific bifacial stone tools persisted in Central-Eastern Europe from the beginning of this ecological shift until the demise of the Neanderthals. This cultural tradition is named Micoquian, and spread across the frosty environment between eastern France, Poland and the Caucasus. Previous genetic analyses showed that two major demographic turnover events in Neanderthal history are associated with the Micoquian cultural tradition. At ~90,000 years ago, western European Neanderthals replaced the local Altai Neanderthals population in Central Asia. Successively, by at least ~45,000 years ago, western European Neanderthals substituted the local groups in the Caucasus.

The paper published in Scientific Reports and led by researchers of the Max Planck Institute for Evolutionary Anthropology in Germany, Wroclaw University, Institute of Systematics and Evolution of Animals Polish Academy of Sciences, and University of Bologna reports the oldest mitochondrial genome of a Neanderthal found in Central-Eastern Europe. The molecular age of ~80,000 years places the tooth from Stajnia Cave in this important period of Neanderthal history when the environment was characterized by extreme seasonality and some groups dispersed eastwards to Central Asia. "Poland, located at the crossroad between the Western European Plains and the Urals, is a key region in understanding these migrations and for solving questions about the adaptability and biology of Neanderthals in periglacial habitat. The Stajnia S5000 molar is truly an exceptional find that sheds light on the debate over the wide distribution of the Micoquian artefacts," says Andrea Picin, lead author of the study and Postdoctoral Researcher at the Max Planck Institute for Evolutionary Anthropology in Leipzig.

Genetic analysis

Neanderthal remains associated with the Micoquian cultural tradition are very few and genetic information has only been extracted from samples of Germany, Northern Caucasus and Altai. "We were aware of the geographical importance of this tooth for adding more chronological points in the distribution map of genetic information of Neanderthals," says Mateja Hajdinjak, co-author of the paper and Postdoctoral Researcher at the Max Planck Institute for Evolutionary Anthropology. "We found that the mitochondrial genome of Stajnia S5000 was closest to the one of a Mezmaiskaya 1 Neanderthal from the Caucasus. We then used the molecular genetic clock in order to determine its approximate age. Although the molecular branch shortening approach comes with a wide error range, crossing the information with the archaeological record permitted us to place the fossil at the beginning of the Last Glacial."

The tooth was discovered in 2007 during fieldwork directed by Mikolaj Urbanowski, co-author of the paper, within animal bones and a few stone tools. The opening of the cave was probably too narrow for prolonged settlement, and Neanderthal occupations were short-term. The site could have been a logistical location settled during forays into the Krakow-Czestochowa Upland.

"We were thrilled when the genetic analysis revealed that the tooth was at least ~80,000 years old. Fossils of this age are very difficult to find and, generally, the DNA is not well preserved," say Wioletta Nowaczewska of Wroclaw University and Adam Nadachowski from the Institute of Systematics and Evolution of Animals Polish Academy of Sciences, co-authors of the paper. "At the beginning, we thought that the tooth was younger since it was found in an upper layer. We were aware that Stajnia Cave is a complex site, and post-depositional frost disturbance mixed artefacts between layers. We are happily surprised by the result." Concerning the paleoanthropological features, Stefano Benazzi of Bologna University, co-author of the paper, adds, "The morphology of the tooth is typical of Neanderthal, which was also confirmed by the genetic analysis. The worn condition of the crown suggests that it belonged to an adult."

Neanderthals in periglacial environments

Archaeologists have been puzzled for a long time by the resilience of Neanderthals in these regions and by the persistence of Micoquian stone tools for more than 50,000 years across a huge area. Beyond the taphonomic issues, the lithic assemblage of Stajnia displays a set of features that are common to several key sites in Germany, Crimea, Northern Caucasus and Altai. These similarities are likely the result of increasing mobility of Neanderthal groups that frequently moved across the Northern and Eastern European Plains chasing cold adapted migratory animals. The Prut and Dniester rivers were probably used as the main corridors of dispersal from Central Europe to the Caucasus. Similar corridors could also have been used at ~45,000 years ago when other western Neanderthals carrying Micoquian stone tools replaced local populations at Mezmaiskaya Cave in the Caucasus.

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New artifacts suggest people arrived in North America earlier than previously thought

Stone tools and other artifacts unearthed from an archeological dig at the Cooper's Ferry site in western Idaho suggest that people lived in the area 16,000 years ago, more than a thousand years earlier than scientists previously thought.

The artifacts would be considered among the earliest evidence of people in North America.

The findings, published today in Science, add weight to the hypothesis that initial human migration to the Americas followed a Pacific coastal route rather than through the opening of an inland ice-free corridor, said Loren Davis, a professor of anthropology at Oregon State University and the study's lead author.

"The Cooper's Ferry site is located along the Salmon River, which is a tributary of the larger Columbia River basin. Early peoples moving south along the Pacific coast would have encountered the Columbia River as the first place below the glaciers where they could easily walk and paddle in to North America," Davis said. "Essentially, the Columbia River corridor was the first off-ramp of a Pacific coast migration route.

"The timing and position of the Cooper's Ferry site is consistent with and most easily explained as the result of an early Pacific coastal migration."

Cooper's Ferry, located at the confluence of Rock Creek and the lower Salmon River, is known by the Nez Perce Tribe as an ancient village site named Nipéhe. Today the site is managed by the U.S. Bureau of Land Management.

Davis first began studying Cooper's Ferry as an archaeologist for the BLM in the 1990s. After joining the Oregon State faculty, he partnered with the BLM to establish a summer archaeological field school there, bringing undergraduate and graduate students from Oregon State and elsewhere for eight weeks each summer from 2009 to 2018 to help with the research.

The site includes two dig areas; the published findings are about artifacts found in area A. In the lower part of that area, researchers uncovered several hundred artifacts, including stone tools; charcoal; fire-cracked rock; and bone fragments likely from medium- to large-bodied animals, Davis said. They also found evidence of a fire hearth, a food processing station and other pits created as part of domestic activities at the site.

Over the last two summers, the team of students and researchers reached the lower layers of the site, which, as expected, contained some of the oldest artifacts uncovered, Davis said. He worked with a team of researchers at Oxford University, who were able to successfully radiocarbon date a number of the animal bone fragments.

The results showed many artifacts from the lowest layers are associated with dates in the range of 15,000 to 16,000 years old.

"Prior to getting these radiocarbon ages, the oldest things we'd found dated mostly in the 13,000-year range, and the earliest evidence of people in the Americas had been dated to just before 14,000 years old in a handful of other sites," Davis said. "When I first saw that the lower archaeological layer contained radiocarbon ages older than 14,000 years, I was stunned but skeptical and needed to see those numbers repeated over and over just to be sure they're right. So we ran more radiocarbon dates, and the lower layer consistently dated between 14,000-16,000 years old."

The dates from the oldest artifacts challenge the long-held "Clovis First" theory of early migration to the Americas, which suggested that people crossed from Siberia into North America and traveled down through an opening in the ice sheet near the present-day Dakotas. The ice-free corridor is hypothesized to have opened as early as 14,800 years ago, well after the date of the oldest artifacts found at Cooper's Ferry, Davis said.

"Now we have good evidence that people were in Idaho before that corridor opened," he said. "This evidence leads us to conclude that early peoples moved south of continental ice sheets along the Pacific coast."

Davis's team also found tooth fragments from an extinct form of horse known to have lived in North America at the end of the last glacial period. These tooth fragments, along with the radiocarbon dating, show that Cooper's Ferry is the oldest radiocarbon-dated site in North America that includes artifacts associated with the bones of extinct animals, Davis said.

The oldest artifacts uncovered at Cooper's Ferry also are very similar in form to older artifacts found in northeastern Asia, and particularly, Japan, Davis said. He is now collaborating with Japanese researchers to do further comparisons of artifacts from Japan, Russia and Cooper's Ferry. He is also awaiting carbon-dating information from artifacts from a second dig location at the Cooper's Ferry site.

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Humans migrated to Mongolia much earlier than previously believed

Mongolia highlighted on globe

Stone tools uncovered in Mongolia by an international team of archaeologists indicate that modern humans traveled across the Eurasian steppe about 45,000 years ago, according to a new University of California, Davis, study. The date is about 10,000 years earlier than archaeologists previously believed.

The site also points to a new location for where modern humans may have first encountered their mysterious cousins, the now extinct Denisovans, said Nicolas Zwyns, an associate professor of anthropology and lead author of the study.

Zwyns led excavations from 2011 to 2016 at the Tolbor-16 site along the Tolbor River in the Northern Hangai Mountains between Siberia and northern Mongolia.

The excavations yielded thousands of stone artifacts, with 826 stone artifacts associated with the oldest human occupation at the site. With long and regular blades, the tools resemble those found at other sites in Siberia and Northwest China -- indicating a large-scale dispersal of humans across the region, Zwyns said.

"These objects existed before, in Siberia, but not to such a degree of standardization," Zwyns said. "The most intriguing (aspect) is that they are produced in a complicated yet systematic way -- and that seems to be the signature of a human group that shares a common technical and cultural background."

That technology, known in the region as the Initial Upper Palaeolithic, led the researchers to rule out Neanderthals or Denisovans as the site's occupants. "Although we found no human remains at the site, the dates we obtained match the age of the earliest Homo sapiens found in Siberia," Zwyns said. "After carefully considering other options, we suggest that this change in technology illustrates movements of Homo sapiens in the region."

Their findings were published online in an article in Scientific Reports.

The age of the site -- determined by luminescence dating on the sediment and radiocarbon dating of animal bones found near the tools -- is about 10,000 years earlier than the fossil of a human skullcap from Mongolia, and roughly 15,000 years after modern humans left Africa.

Evidence of soil development (grass and other organic matter) associated with the stone tools suggests that the climate for a period became warmer and wetter, making the normally cold and dry region more hospitable to grazing animals and humans.

Preliminary analysis identifies bone fragments at the site as large (wild cattle or bison) and medium size bovids (wild sheep, goat) and horses, which frequented the open steppe, forests and tundra during the Pleistocene -- another sign of human occupation at the site.

The dates for the stone tools also match the age estimates obtained from genetic data for the earliest encounter between Homo sapiens and the Denisovans.

"Although we don't know yet where the meeting happened, it seems that the Denisovans passed along genes that will later help Homo sapiens settling down in high altitude and to survive hypoxia on the Tibetan Plateau," Zwyns said. "From this point of view, the site of Tolbor-16 is an important archaeological link connecting Siberia with Northwest China on a route where Homo sapiens had multiple possibilities to meet local populations such as the Denisovans."

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Scientists document late Pleistocene/early Holocene Mesoamerican stone tool tradition

Belize highlighted on map

From the perspective of Central and South America, the peopling of the New World was a complex process lasting thousands of years and involving multiple waves of Pleistocene and early Holocene period immigrants entering into the Neotropics.

Paleoindian colonists arrived in waves of immigrants entering the Neotropics, a region starting in the humid rainforests of southern Mexico before 13,000 years ago and brought with them technologies developed for adaptation to environments and resources found in North America.

As the ice age ended across the New World people adapted more generalized stone tools to exploit changing environments and resources. In the Neotropics these changes would have been pronounced as patchy forests and grasslands gave way to broadleaf tropical forests.

In new research published recently in PLOS One titled "Linking late Paleoindian stone tool technlogies and populations in North, Central and South America," scientists from The University of New Mexico led a study in Belize to document the very earliest indigenous stone tool tradition in southern Mesoamerica.

"This is an area of research for which we have very poor data regarding early humans, though this UNM-led project is expanding our knowledge of human behavior and relationships between people in North, Central and South America," said lead author Keith Prufer, professor from The University of New Mexico's Department of Anthropology.

This research, funded by grants from the National Science Foundation and the Alphawood Foundation, focuses on understanding the Late Pleistocene human colonization of tropics in the broad context of global changes occurring at the end of the last ice age (ca. 12,000-10,000 years ago). The research suggests the tools are part of a human adaptation story in response to emerging tropical conditions in what is today called the Neotropics, a broad region south of the Isthmus of Tehuantepec (in S Mexico).

As part of the research, the team conducted extensive excavations at two rock shelter sites from 2014-2018. The excavation sites, located in the Bladen Nature Reserve, are almost 30 miles from the nearest road or modern human settlement in a large undisturbed rainforest that is one of the best-protected wildlife refuges in Central America.

"We have identified and established an absolute chronology for the earliest stone tool types that are indigenous to Central America," said Prufer. "These have clear antecedents with the earliest known humans in both South America and North America, but appear to show more affinity with slightly younger Late Paleoindian toolkits in the Amazon and Northern Peru than with North America."

The research represents the first endogenous Paleoindian stone tool technocomplex recovered from well-dated stratigraphic contexts for Mesoamerica. Previously designated, these artifacts share multiple features with contemporary North and South American Paleoindian tool types. Once hafted, these bifaces appear to have served multiple functions for cutting, hooking, thrusting, or throwing.

"The tools were developed at a time of technological regionalization reflecting the diverse demands of a period of pronounced environmental change and population movement," said Prufer. "Combined stratigraphic, technological, and population paleogenetic data suggests that there were strong ties between lowland neotropic regions at the onset of the Holocene."

These findings support previous UNM research suggesting strong genetic relationships between early colonists in Central and South America, following the initial dispersal of humans from Asia into the Americas via the arctic prior to 14,000 years ago.

"We are partnering with Belizean conservation NGO Ya'axche Conservation Trust in our fieldwork to promote the importance of ancient cultural resources in biodiversity and protected areas management," said Prufer. "We spend a month every year camped out with no access to electricity, internet, phone or resupplies while we conduct excavations."

This field research involves several UNM graduate students in Archaeology and Evolutionary Anthropology as well as collaborators at Exeter University (UK) and Arizona State University. The analysis for this study was done in part at UNM's Center for Stable Isotopes, as well as with co-authors at Penn State and UC Santa Barbara. At UNM this involved the new radiocarbon preparation laboratories which are part of the Center for Stable isotopes, one of the anchors of UNM's interdisciplinary PAIS research and teaching facility.

The senior co-authors are world leaders in the study of early humans in the tropics and are committed to conservation efforts of cultural resources and regional biodiversity. Additionally, Prufer's long-term collaboration in indigenous Maya communities in the region was critical to the success of this project.

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Oldest flaked stone tools point to the repeated invention of stone tools

Ethiopia map.

A new archaeological site discovered by an international and local team of scientists working in Ethiopia shows that the origins of stone tool production are older than 2.58 million years ago. Previously, the oldest evidence for systematic stone tool production and use was 2.58 to 2.55 million years ago.

Analysis by the researchers of early stone age sites, published this week in the Proceedings of the National Academy of Sciences, suggests that stone tools may have been invented many times in many ways before becoming an essential part of the human lineage.

The excavation site, known as Bokol Dora 1 or BD 1, is close to the 2013 discovery of the oldest fossil attributed to our genus Homo discovered at Ledi-Geraru in the Afar region of northeastern Ethiopia. The fossil, a jaw bone, dates to about 2.78 million years ago, some 200,000 years before the then oldest flaked stone tools. The Ledi-Geraru team has been working for the last five years to find out if there is a connection between the origins of our genus and the origins of systematic stone tool manufacture.

A significant step forward in this search was uncovered when Arizona State University geologist Christopher Campisano saw sharp-edged stone tools sticking out of the sediments on a steep, eroded slope.

"At first we found several artifacts lying on the surface, but we didn't know what sediments they were coming from," says Campisano. "But when I peered over the edge of a small cliff, I saw rocks sticking out from the mudstone face. I scaled up from the bottom using my rock hammer and found two nice stone tools starting to weather out."

It took several years to excavate through meters of sediments by hand before exposing an archaeological layer of animal bones and hundreds of small pieces of chipped stone representing the earliest evidence of our direct ancestors making and using stone knives. The site records a wealth of information about how and when humans began to use stone tools.

Preservation of the artifacts comes from originally being buried close to a water source.

"Looking at the sediments under a microscope, we could see that the site was exposed only for a very short time. These tools were dropped by early humans at the edge of a water source and then quickly buried. The site then stayed that way for millions of years," noted geoarchaeologist Vera Aldeias of the Interdisciplinary Center for Archaeology and Behavioral Evolution at the University of Algarve, Portugal.

Kaye Reed, who studies the site's ecology, is director of the Ledi-Geraru Research Project and a research associate with Arizona State University's Institute of Human Origins along with Campisano, notes that the animals found with these tools were similar to those found only a few kilometers away with the earliest Homo fossils.

"The early humans that made these stone tools lived in a totally different habitat than 'Lucy' did," says Reed. "Lucy" is the nickname for an older species of hominin known as Australopithecus afarensis, which was discovered at the site of Hadar, Ethiopia, about 45 kilometers southwest of the new BD 1 site. "The habitat changed from one of shrubland with occasional trees and riverine forests to open grasslands with few trees. Even the fossil giraffes were eating grass!"

In addition to dating a volcanic ash several meters below the site, project geologists analyzed the magnetic signature of the site's sediments. Over the Earth's history, its magnetic polarity has reversed at intervals that can be identified. Other earlier archaeological sites near the age of BD 1 are in "reversed" polarity sediments. The BD 1 site is in "normal" polarity sediments. The reversal from "normal" to "reversed" happened at about 2.58 million years ago, geologists knew that BD 1 was older than all the previously known sites.

The recent discovery of older hammering or "percussive" stone tools in Kenya dated to 3.3 million years ago, described as "Lomekwian," and butchered bones in Ethiopia shows the deep history of our ancestors making and using tools. However, recent discoveries of tools made by chimpanzees and monkeys have challenged "technological ape" ideas of human origins.

Archaeologists working at the BD 1 site wondered how their new stone tool discovery fit into this increasingly complex picture. What they found was that not only were these new tools the oldest artifacts yet ascribed to the "Oldowan," a technology originally named after finds from Olduvai Gorge in Tanzania, but also were distinct from tools made by chimpanzees, monkeys or even earlier human ancestors.

"We expected to see some indication of an evolution from the Lomekwian to these earliest Oldowan tools. Yet when we looked closely at the patterns, there was very little connection to what is known from older archaeological sites or to the tools modern primates are making," said Will Archer of the Max Planck Institute for Evolutionary Anthropology in Leipzig and the University of Cape Town.

The major differences appear to be the ability for our ancestors to systematically chip off smaller sharp-edged tools from larger nodules of stone. Chimpanzees and monkeys generally use tools for percussive activities, to hammer and bash food items like nuts and shellfish, which seems to have been the case with the 3.3 million year old Lomekwian tools as well.

Something changed by 2.6 million years ago, and our ancestors became more accurate and skilled at striking the edge of stones to make tools. The BD 1 artifacts captures this shift.

It appears that this shift in tool making occurred around the same time that our ancestor's teeth began to change. This can be seen in the Homo jaw from Ledi-Geraru. As our ancestors began to process food prior to eating using using stone tools, we start to see a reduction in the size of their teeth. Our technology and biology were intimately intertwined even as early as 2.6 million years ago.

The lack of clear connections with earlier stone tool technology suggests that tool use was invented multiple times in the past.

David Braun, an archaeologist with George Washington University and the lead author on the paper, noted, "Given that primate species throughout the world routinely use stone hammers to forage for new resources, it seems very possible that throughout Africa many different human ancestors found new ways of using stone artifacts to extract resources from their environment. If our hypothesis is correct then we would expect to find some type of continuity in artifact form after 2.6 million years ago, but not prior to this time period. We need to find more sites."

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