text: Thank you for your interest in spreading the word about Science. 
   
   NOTE: We only request your email address so that the person you are recommending the page to knows that you wanted them to see it, and that it is not junk mail. We do not capture any email address. ||||| Dramatic shifts in the East African climate may have driven toolmaking advances and the development of trading networks among Homo sapiens or their close relatives by the Middle Stone Age, roughly 320,000 years ago. That’s the implication of discoveries reported in three papers published online March 15 in Science. 
   
   Newly excavated Middle Stone Age tools and red pigment chunks from southern Kenya’s Olorgesailie Basin appear to have been part of a long trend of climate-driven behavior changes in members of the Homo genus that amped up in H. sapiens. Locations of food sources can vary unpredictably on changing landscapes. H. sapiens and their precursors responded by foraging over larger areas with increasingly smaller tools, the researchers propose. Obsidian used for the Middle Stone Age tools came from far away, raising the likelihood of long-distance contacts and trading among hominid populations near humankind’s root. 
   
   At roughly 320,000 years old, the excavated Middle Stone Age tools are the oldest of their kind, paleoanthropologist Rick Potts and colleagues report in one of the new papers. Researchers had previously estimated that such tools — spearpoints and other small implements struck from prepared chunks of stone — date to no earlier than 280,000 to possibly 300,000 years ago. Other more primitive, handheld cutting stones made of local rock date from around 1.2 million to 499,000 years ago at Olorgesailie. Gradual downsizing of those tools, including oval hand axes, occurred from 615,000 to 499,000 years ago, a stretch characterized by frequent shifts between wet and dry conditions, the scientists say. 
   
   It’s not known whether that tool trend continued or if a sudden transition to Middle Stone Age implements happened between 499,000 and 320,000 years ago. Erosion at Olorgesailie artifact sites has destroyed sediment from that time period, leaving the nature of toolmaking during that time gap a mystery. Age estimates relied on measures of the decay of radioactive forms of argon and uranium in volcanic ash layers framing tool-bearing sediment. It’s unclear whether Homo sapiens or a closely related species made Olorgesailie’s Middle Stone Age tools, since no hominid fossils have been found there. 
   
   Back-and-forth shifts from dry to wet conditions — many happening over only a few years or decades — continued to regularly reshape the Olorgesailie landscape around 320,000 years ago, conclude Potts, of the Smithsonian Institution in Washington, D.C., and colleagues in another of the new papers. That timing coincides roughly with the emergence of H. sapiens (SN: 12/23/17, p. 24). The team’s climate reconstruction is based on microscopic and chemical analyses of the region’s soil. 
   
   A substantial number of Olorgesailie’s Middle Stone Age tools are made from obsidian that came from at least 25 to 50 kilometers away from the excavation sites. At one Olorgesailie site in particular, 42 percent of more than 3,400 stone artifacts were obsidian. Some of those finds display signs of having been attached to handles, likely as spearpoints, a group led by archaeologist Alison Brooks of George Washington University in Washington, D.C., reports in the third paper. Brooks is also a coauthor on the other studies. 
   
   Formation of trading networks among dispersed groups of H. sapiens, or possibly among closely related populations, best explains how large amounts of obsidian turned up at Olorgesailie by 320,000 years ago, contends Potts, who coauthored the third paper. “Social networking during a long period of climate variability was a key to success for early Homo sapiens,” he says. “Greater mobility encouraged inventive thinking about how to acquire resources.” Potts has long argued that H. sapiens and close evolutionary relatives evolved to deal with constantly changing environments (SN: 8/20/05, p. 116). 
   
   Still, factors other than climate fluctuations, such as hominid population declines or surges, may also have spurred ancient tool innovations to acquire more or different types of food, cautions archaeologist Yonatan Sahle of the University of Tübingen in Germany. 
   
   In addition to the obsidian tools, a total of 88 pigment lumps, including two pieces with grinding marks, came from an undetermined distance outside the Olorgesailie vicinity, Brooks’ group says. Pigment applied to one’s body or belongings may have signaled group identity or social status, the researchers suggest. 
   
   The new reports fit with genetic evidence that H. sapiens originated in Africa between 350,000 and 260,000 years ago (SN: 10/28/17, p. 16), says Stone Age archaeologist Marlize Lombard of the University of Johannesburg. Smaller, more specialized Middle Stone Age tools appearing along with pigment “provide strong indicators that by around 300,000 years ago we were well on our way to becoming modern humans in Africa,” she holds. 
   
   Ancient toolmaking approaches varied greatly from one part of Africa to another, with hominids employing diverse mixes of old-school chopping tools and newer, sharp points, says archaeologist John Shea of Stony Brook University in New York. At Olorgesailie and elsewhere, he says, “early Homo sapiens and their immediate African ancestors were at least as smart as the scientists investigating them.” 
   
   Editors’ note: This story was updated on March 21, 2018, to correct the percentage of stone artifacts made from obsidian at one Olorgesailie site. ||||| Scientists Are Amazed By Stone Age Tools They Dug Up In Kenya 
   
   Enlarge this image toggle caption Jay Reed/NPR Jay Reed/NPR 
   
   Our ancestors in Kenya's Southern Rift Valley made some pretty innovative tools. And they made them far earlier than previously thought. 
   
   The oldest innovations were axes designed to be held in the palm of the hand. They were shaped like a tear drop, with a rounded end and a pointed eye. The edges were wavy and sharp. And they look as if they were great at chopping down branches — or chopping up the carcass of a large animal. 
   
   toggle caption Jay Reed/NPR 
   
   "I think of the hand axes as the Swiss army knife of the Stone Age," says paleoanthropologist Rick Potts, director of the Human Origins program at the Smithsonian Museum of Natural History and one of the lead scientists in a new study by a team of international scientists. 
   
   The researchers also found that the next technological revolution, marking the beginning of the Middle Stone Age happened tens of thousands of years earlier than previously thought. 
   
   And the researchers think that long periods of stress from repeated earthquakes and cycles of drought and heavy rains may have pushed these early humans to partner up with neighboring communities to come up with ways to cope. 
   
   toggle caption Jay Reed 
   
   The team was digging in a region called Olorgesailie in southern Kenya, an area filled with layers of sediment dating back 1.2 million years. The oldest stone tools discovered there are characteristic of what's called the Acheulian culture of the Early Stone Age and consisted mostly of the hand axes. 
   
   Enlarge this image toggle caption Human Origins Program/Smithsonian Human Origins Program/Smithsonian 
   
   In addition to branch- and carcass-chopping, the axes were likely used to dig for water to drink or tubers to eat. The carcasses probably belonged to large animals like the giant (now extinct) ancestors of hippos, elephants and wild pigs that roamed the grasslands back then. Potts says the ancient humans of that time likely scavenged dead animals, as their heavy, clunky hand axes wouldn't have served well for hunting big game. "These are very large tools," he says. "They might have been thrown but not very accurately." 
   
   toggle caption Jay Reed/NPR 
   
   Nevertheless, these hand axes served the ancient humans well for several hundred thousand years — from 1.2 million years ago to 500,000 years ago — and the technology remained largely unchanged during the time. 
   
   But around 320,000 years ago, the ancient humans seem to have switched to an entirely new technology. The scientists found numerous smaller, flatter, sharper stone tools. 
   
   "We see a smaller technology, a more diverse series of stone tools," says Potts. These tools were designed for specific purposes — some were used as blades, some as scrapers or spear heads. The scientists report their findings in three new studies published Thursday in the journal Science. 
   
   "In Olorgesailie, you have the only record of the last million years in Africa," says Marta Mirazon Lahr, a paleoanthropologist who wasn't involved in the new study. And it's "the earliest ever documented Middle Stone Age in the whole continent." 
   
   The new studies also show that by 320,000 years ago this technology was well established in the region, suggesting that human ancestors likely started developing it even earlier, she says. 
   
   "The technology they have is not a crude, early version of the Middle Stone Age. It is the full-blown Middle Stone Age," Lahr says. "They have stone tools that are small, that are prepared and retouched, that are made with technique thought to come hundreds of thousands of years later." 
   
   toggle caption Jay Reed/NPR 
   
   The diversity of stone tools from the Middle Stone Age suggests advanced thinking and planning. "The flakes are being much more carefully prepared for a particular purpose," says Alison Brooks, an anthropologist at George Washington University and an author of the three studies. 
   
   "They are fairly small in size, compared to the technology of earlier people. And in addition, they are made with much finer grained material," which allowed them to better control shapes and sizes of the stone tools. 
   
   "We see the ability to produce small triangular points, that look like they were projectile points," says Potts. "They were tapered at the end, so that could have been put on the shaft of something that flew through the air." In other words, a potentially lethal spear. 
   
   So our ancestors likely shifted from scavenging to hunting. An analysis of the fossilized animal bones found in the sediments show that people in that period were eating a range of mammals — which were by now much smaller, and closer in size to the animals of today — including hares, rabbits and springbok and even a couple of species of birds and fishes, says Brooks. 
   
   And they weren't just picking up nearby stones to create their weapons. Earlier hand axes were made primarily from volcanic basalt, sourced within 2 to 2.5 miles of where these humans lived. The latter weapons were made of stones like obsidian, which originated far from Olorgesailie. 
   
   toggle caption Jay Reed/NPR 
   
   "That black obsidian, that rare rock was being transported, brought in in chunks, from 15 to 30 miles away," says Potts. "We have a couple of rocks that were brought from up to 55 miles away." 
   
   These distances are far greater than what modern-day hunter gatherers travel over the course of a year, he says. 
   
   "They weren't just traveling long distances and chipping rocks as they go," he adds. "If they did that, then there would have just been small chips of obsidian left at the archaeological sites where we dig. Instead we see large pieces of raw material coming in. The rocks were shaped at Olorgesaile itself." 
   
   That kind of exchange of raw materials is a tell-tale sign of exchange between different groups of people, the scientists say. "In the Middle Stone Age, we begin to see the early stages of social networks, of being aware of another group and exchanging rocks over longer distances." 
   
   Potts and his colleagues also find evidence of exchange of brightly colored red and black rocks that were then drilled into, possibly to extract pigment. This is the earliest evidence of the extraction of pigments, says Lahr. 
   
   It's also evidence of a complex culture, where the ancient humans probably used pigments symbolically — perhaps to paint themselves, or their hides, or weapons. And where different groups exchanged raw materials (and possibly food). 
   
   toggle caption Jay Reed/NPR 
   
   There's that same kind of exchange today, says Brooks, referring to hunter gatherer groups like the Hadza people of northern Tanzania. 
   
   "They deliberately maintain distant contacts with people in these other groups," she says. They have strategies to maintain these contacts — either by encouraging their children to marry into these other groups, or they take trips to visit the groups, to maintain ties by giving gifts. "It's a way of building up these distant contacts, which are extremely important for their survival." 
   
   During times of stress, when food or water is scarce, people from one group can disperse and take shelter with other groups that they've cultivated a relationship with. "So the networks are like money in the bank, or wheat in your silo or cows in your barn," says Brooks. "They don't have any other way of saving for a rainy day." 
   
   And as she and her colleagues show, the beginning of the Middle Stone Age in Kenya was preceded by a long and tumultuous phase in the region. 
   
   "Things were going haywire, in terms of the development of geological faults, earthquake activity that moved the low places high and the high places low," says Potts. "It changed the shape of the landscape." This was accompanied by repeated cycles of droughts and high rainfall. 
   
   "And it is precisely during those time periods that we expect to see hunting and gathering people to move further distances," says Potts, "and to begin to nurture relationships with groups beyond their own group." 
   
   It is no different than what humans all over the world do today, he adds. When times are tough, we look for greener pastures. The archaeological records from the Middle Stone Age at Olorgesailie reveal "the roots of that kind of migration," he says. ||||| Just 20 years ago, many archaeologists believed there was a “human revolution” 40,000-50,000 years ago during which modern behaviours such as symbolism, innovation and art suddenly arose. This was thought to have enabled a major shift in cognitive organisation and probably the advent of complex language. At the time, the earliest modern human fossils had been found in Africa and dated to some 100,000 years ago, leaving a gap between the emergence of anatomically modern humans and behaviourally modern humans. 
   
   This gap in the development suggested that we only achieved “modernity” as our species migrated out of Africa and into the rest of the Old World. But this view is increasingly being challenged. Just weeks ago, we learned that Neanderthals could paint images. Now, three new papers, published in Science, show that technologically advanced behaviours occurred much earlier than we thought in the African stone age. 
   
   Not all researchers supported the view that modernity arose outside of Africa. Writing at the turn of the millennium, archaeologists Sally McBrearty and Allison Brooks complained that this view was Eurocentric and brought about by a profound under-appreciation of the depth and complexity of the African archaeological record. They argued that components of the “human revolution” were to be found in the African Middle Stone Age some 280,000-50,000 years ago. 
   
   The role of climate change 
   
   Now, two decades later, Brooks and her colleagues have presented well-dated evidence from the Olorgesailie Basin in Kenya that places the evolution of some of these behaviours much further back in time. They highlight technological change at around 300,000 years ago that likely occurred in response to the effects of long-term, global environmental and climatic change. 
   
   Human Origins Program, Smithsonian 
   
   Around 800,000 years ago, the Olorgesailie Basin comprised a series of floodplains. Over the course of the next several hundred thousand years, the climate changed and the area developed into a vast arid grassland with massive turnover of prey mammal species as a consequence. 
   
   This would have made life difficult for early humans in the region by making food sources unpredictable. Human populations needed to adapt or go extinct. The crux of these papers is that hominin populations did not disappear – so at least some of them must have adapted technologically and culturally, with the environment driving greater mobility, information gathering and sharing, and innovation. 
   
   Based on excavations at five sites dating from 320,000 years ago, the team found distinct differences in the forms of stone tools compared to older deposits in the area – suggesting technological innovation had taken place. Older sites yielded large, bulky stone tools such as hand axes and cleavers. This technology is generally referred to as Acheulean (Early Stone Age). 
   
   In contrast, these sites at Olorgesailie contained much smaller, standardised pieces such as points and blades, some modified in a manner that made hafting possible. The team therefore classified them as Middle Stone Age industries. Many of the tools were made on obsidian (a volcanic glass) rather than rock. What’s more, chemical testing indictated that these raw materials came from 25-50 km away, and some from further afield. Some of these tools were made at the site and not brought in as finished items. 
   
   Obsidian wasn’t the only exotic material – they also discovered bright red ochre pigment displaying evidence of grinding and cut marks, which makes this among the oldest known pigments used to colour rocks in the archaeological record. 
   
   Human Origins Program, Smithsonian 
   
   Together, the glass and ochre mark the earliest evidence for long-distance transport of raw materials in the East African record. 
   
   Gap in the evidence 
   
   Across Africa, the Middle Stone Age is characterised by the absence or rarity of large cutting tools and the presence of prepared core technologies for making sophisticated points and blades. Crucially, the transition between the African Early and Middle Stone Age occurred around the time that our own species, Homo sapiens, was evolving across the continent. 
   
   It might therefore be tempting to treat the appearance of the earliest Middle Stone Age technology as a cultural marker linked to the evolution and appearance of our own species – a smoking gun for evidence of the modern human mind. But it is probably too soon to jump to that conclusion. 
   
   Elsewhere across Africa, the association between Early and Middle Stone Age and pre- and fully-modern human fossils remains complex and confusing. Before 400,000 years ago, there are Early Stone Age sites which contain components such as blades and prepared cores. These are associated with archaic rather than modern human fossils such as at the Cave of Hearths. Conversely, we know that the production of Acheuelean large cutting tools by modern humans continued well into the period of the Middle Stone Age – such as at the 160,000-year-old site of Herto. 
   
   Lee Berger et al/eLife Journal 
   
   What is genuinely exciting about the discoveries in the Olorgesailie Basin is that we now know that one or more hominin groups were doing seemingly “modern” things at this critical time period. New tool forms and exotic materials require an understanding of space and time – bringing materials over great distances and passing on technological skills through successive generations. This suggests expanded social networks, transmission of information and technological innovation. 
   
   Rethinking the revolution 
   
   It does seem that the “human revolution” that made us modern never was – archaeological evidence for modern behaviours arose much earlier, starting in groups that predated our own species. Every criterion that has historically been used to differentiate modern humans from archaic humans – culture, art, treatment of the dead, ornamentation and abstract symbolism – has much older examples. 
   
   What remains to be understood, however, is the relationship between complex behaviours and hominin species from 500,000 years to 160,000 years ago when many species of hominins (not just modern humans) inhabited the African landscape. Gradual complex change is more difficult to interpret than revolution.
target: – For decades, the human story was one told through signs of modernity—art, tools, burials—found only after Homo sapiens left Africa. Recent discoveries pushing back the date of departure are helping to change that narrative, as are three new studies in Science. Together, they describe the earliest stone tools of their kind in East Africa as well as the earliest evidence for long-distance transport of raw materials in the region, per Science News. Researchers previously believed the Early Stone Age marked by large, primitive tools (hand axes and cleavers) made way for the Middle Stone Age and its smaller tools (spearpoints and blades) around 280,000 years ago. But stone tools found in Kenya's Olorgesailie Basin show hominin groups—it's not clear which species is responsible—had developed these more advanced tools approximately 320,000 years ago. "We see a smaller technology, a more diverse series of stone tools … designed for specific purposes," researcher Rick Potts tells NPR. An expert not involved in the study says the tools are so "prepared and retouched" they suggest the Middle Stone Age likely started even earlier. What drove it? Microscopic and chemical analyses of the region's soil show the landscape was rapidly shifting between wet and dry conditions, meaning hominins might have been forced to adapt. But as the technology also coincides with the emergence of Homo sapiens in Africa, it's possible that the human mind deserves credit. The tools themselves suggest the development of trading networks, too. Some were made of rocks carried from 55 miles away, says Potts. Others were made of obsidian from as far as 30 miles away, per the Conversation. (These stone tools are also making waves.)