World’s oldest stone tools discovered in Kenya
April 14, 2015
SAN FRANCISCO, CALIFORNIA—Researchers at a meeting here say they have found the oldest tools made by human ancestors—stone flakes dated to 3.3 million years ago. That’s 700,000 years older than the oldest-known tools to date, suggesting that our ancestors were crafting tools several hundred thousand years before our genus Homoarrived on the scene. If correct, the new evidence could confirm disputed claims for very early tool use, and it suggests that ancient australopithecines like the famed “Lucy” may have fashioned stone tools, too.
Until now, the earliest known stone tools had been found at the site of Gona in Ethiopia and were dated to 2.6 million years ago. These belonged to a tool technology known as the Oldowan, so called because the first examples were found more than 80 years ago at Olduvai Gorge in Tanzania by famous paleoanthropologists Louis and Mary Leakey. Then, in 2010, researchers working at the site of Dikika in Ethiopia—where an australopithecine child was also discovered—reported cut marks on animal bones dated to 3.4 million years ago; they argued that tool-using human ancestors made the linear marks. The claim was immediately controversial, however, and some argued that what seemed to be cut marks might have been the result of trampling by humans or other animals. Without the discovery of actual tools, the argument seemed likely to continue without resolution.
Now, those missing tools may have been found. In a talk at the annual meeting of the Paleoanthropology Society here, archaeologist Sonia Harmand of Stony Brook University in New York described the discovery of numerous tools at the site of Lomekwi 3, just west of Lake Turkana in Kenya, about 1000 kilometers from Olduvai Gorge. In 2011, Harmand’s team was seeking the site where a controversial human relative called Kenyanthropus platyops had been discovered in 1998. They took a wrong turn and stumbled upon another part of the area, called Lomekwi, near where Kenyanthropus had been found. The researchers spotted what Harmand called unmistakable stone tools on the surface of the sandy landscape and immediately launched a small excavation.
More tools were discovered under the ground, including so-called cores from which human ancestors struck off sharp flakes; the team was even able to fit one of the flakes back to its original core, showing that a hominin had crafted and then discarded both core and flake in this spot. The researchers returned for more digging the following year and have now uncovered nearly 20 well-preserved flakes, cores, and anvils apparently used to hold the cores as the flakes were struck off, all sealed in sediments that provided a secure context for dating. An additional 130 pieces have also been found on the surface, according to the talk.
“The artifacts were clearly knapped [created by intentional flaking] and not the result of accidental fracture of rocks,” Harmand told the meeting. Analysis of the tools showed that they had been rotated as flakes were struck off, which is also how Oldowan tools were crafted. The Lomekwi tools were somewhat larger than the average Oldowan artifacts, however. Dating of the sediments using paleomagnetic techniques—which track reversals in Earth’s magnetic field over time and have been used on many hominin finds from the well-studied Lake Turkana area—put them at about 3.3 million years old.
Although very recent research has now pushed back the origins of the genus Homo to as early as 2.8 million years ago, the tools are too old to have been made by the first fully fledged humans, Harmand said in her talk. The most likely explanation, she concluded, was that the artifacts were made either by australopithecines similar to Lucy or byKenyanthropus. Either way, toolmaking apparently began before the birth of our genus. Harmand and her colleagues propose to call the new tools the Lomekwian technology, she said, because they are too old and too distinct from Oldowan implements to represent the same technology.
Researchers who have seen the tools in person are enthusiastic about the claim. The finds are “very exciting,” says Alison Brooks, an anthropologist at George Washington University in Washington, D.C. “They could not have been created by natural forces … [and] the dating evidence is fairly solid.” She agrees that the tools are too early to have been made by Homo, suggesting that “technology played a major role in the emergence of our genus.”
The claim also looks good to paleoanthropologist Zeresenay Alemseged of the California Academy of Sciences here, a leader of the team that found cut marks on the Dikika animal bones. (At the meeting, another team member presented new arguments for the cut marks’ authenticity.) “With the cut marks from Dikika we had the victim” of the stone tools, Alemseged says. “Harmand’s discovery gives us the smoking gun.”
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|Jill Pruetz says the environment and social tolerance may explain why savanna chimps,|
particularly females, are more likely to hunt with tools. | Credit: Image courtesy of BBC
Iowa State anthropologist finds female chimps more likely to use tools when hunting
April 15, 2015
It was a discovery that changed what researchers knew about the hunting techniques of chimpanzees. In 2007, Jill Pruetz first reported savanna chimps at her research site in Fongoli, Senegal, were using tools to hunt prey. That alone was significant, but what also stood out to Pruetz was the fact that female chimps were the ones predominantly hunting with tools.
It was a point some dismissed or criticized because of the small sample size, but the finding motivated the Iowa State University anthropology professor to learn more. In the years following, Pruetz and her research team have documented more than 300 tool-assisted hunts. Their results, published in the journal Royal Society Open Science, support the initial findings - female chimps hunt with tools more than males.
Generally, adult male chimps are the main hunters and capture prey by hand. Researchers observed both male and female chimps using tools, but more than half of the hunts - 175 compared to 130 - were by females. While males made up about 60 percent of the hunting group, only around 40 percent of the hunts were by males.
"It's just another example of diversity in chimp behavior that we keep finding the longer we study wild chimps," Pruetz said. "It is more the exception than the rule that you'll find some sort of different behavior, even though we've studied chimps extensively."
Both male and female chimps primarily pursued galagos, or bush babies, in tool-assisted hunts. Pruetz says the chimps used a spear-like tool to jab at the animal hiding in tree cavities. She added that one explanation for the sex difference in tool use is that male chimps tended to be more opportunistic.
"What would often happen is the male would be in the vicinity of another chimp hunting with a tool, often a female, and the bush baby was able to escape the female and the male grabbed the bush baby as it fled," Pruetz said.
Why only Fongoli?
The savanna chimps at Fongoli are the only non-human population to consistently hunt prey with tools. Why is that the case? Pruetz, Walvoord Professor of Liberal Arts & Sciences at Iowa State, says a better question may be why are chimps at other sites not using this technique? It may be that they never learned the technique, she said. Tool hunting also may be a result of social tolerance that doesn't exist at other chimp sites.
"At Fongoli, when a female or low-ranking male captures something, they're allowed to keep it and eat it. At other sites, the alpha male or other dominant male will come along and take the prey. So there's little benefit of hunting for females, if another chimp is just going to take their prey item."
The environment is another factor. Pruetz says there are no red colobus monkeys, the preferred prey of chimps at other sites, because of the dry conditions at Fongoli. The bush babies are more prevalent and prey that female chimps can access using tools.
Hunting vs. gathering
Pruetz, a National Geographic Emerging Explorer, is often asked why the female's use of tools is considered hunting rather than gathering. It's a question that reflects stereotypes associated with female chimp behavior. The similarities to termite or ant fishing, which is sometimes used as a comparison for tool-assisted hunting, are superficial, she said. The behavior of the prey and effort required by the hunter is different.
"Fishing for termites is a very different activity than jabbing for a bush baby," Pruetz said. "With fishing, termites grab on to a twig and don't let go and the chimp eats the termites off the twig. When hunting, the bush baby tries to bite, escape or hide from the chimp. The chimps are really averse to being bitten by a bush baby."
While a bush baby is smaller than, and not as fierce as a monkey, Pruetz says it is really no different than humans hunting doves instead of deer. Ultimately, the tool-assisted hunting allows female chimps, which may be less likely to run down prey, access to a nutritional food source, Pruetz said.
Provided by Iowa State University
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|Archaeological Dating of Human Origins|
|Early Human Migration Map|
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