What Stone-Moving Macaques Can Tell Us About Early Human Tool Use

Consider the possibility that all human technology began with mistakes, or at least a lack of hand-eye coordination. To pursue this idea, Lydia Luncz and Tomos Profet of the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, traveled to an abandoned oil palm plantation near Phang Nga Bay, Thailand, and collected nut crack stones used by the resident soldiers. Long tails. Macaques extract oil palm kernels by placing them on a flat stone and pounding their shells against another stone. These monkeys often miss nuts and unknowingly break the stones, causing sharp cracks. In a new study, Lunch and Prophet argue that such misshapen flakes may have been the first step in creating sharp tools used by our ancestors or now-extinct early human relatives to slaughter animals and cut plants for food. In other words, these types of tools have evolved to make us more effective hunter-gatherers and technological scavengers.

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Macaques are one of only three modern non-human primate species (the other two being chimpanzees and capuchin monkeys) that use stone tools. Luncz and Proffitt have been studying the idea that sharp spikes produced accidentally during activities such as nut-cracking may have caused humans and their extinct ancestors and close relatives, the hominins, to deliberately make the particles into tools. “This is completely wild behavior,” Proffitt says. “And it’s a habit of getting food. So from that point of view, you can start to say that this could be a mechanism for the creation of Flak technology.

For their study published on Friday by Advances in scienceAn international team of researchers collected more than 1,100 stone fragments used by macaques in Thailand to crack open oil palm nuts and compared them with archaeological collections from early stone tool sites in Tanzania, Kenya and Ethiopia. Their analysis revealed a surprising fact: Flakes produced by the macaques unknowingly resemble ancient stone tools deliberately made by hominins: the Lomequian and Oldowan stone tools found at sites dating from 3.3 million to 1.5 million years ago. . “If we took a collection like the one we found with macaques and dumped them somewhere in East Africa, everyone would definitely think they were made by ancient hominins,” Lunch says.

Luncz and Proffitt obtained similar results with stone plaques produced by capuchin monkeys in Brazil’s Serra da Capivara National Park. “What’s really exciting is that we found another primate species on the other side of the world that shows the same phenomenon,” says Lunch. “You don’t need a huge brain to make sharp cutting tools. The problem is using stone tools. I think this is where the difference lies. This difference shows the assemblage of Makak tools and flakes compared to tools from Lomekwian or Oldowan sites. The macaques don’t use the sharp fangs they create for anything, Lunch says, adding that the monkeys have sharp teeth and don’t need cutting tools. It shows that ancient stone tools were used for cutting works.

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“I think this study is important because it drives home the point that people need to give careful behavioral meaning to their objects,” said paleoanthropologist Thomas Plummer of Queens College, City University of New York, who is not part of Luncz. The Proffitt Group. Plummer is part of a research team studying fossil sites in Nyanga, Kenya. Excavations at sites dating back three million to 2.6 million years have yielded Oldowan tools and two missing teeth from a hominin species. The researchers examined the methods of use on the tools and found that some were employed to beat and process plant foods. Some sherds also show damage to their edges, indicating that they were used for cutting. Cut marks on hippopotamus bones and cattle fossils revealed that hominins used stone tools to butcher the animals, making it clear that sharp stone tools were the result of striking activities other than intentional. That does not mean that those tools were made by human ancestors.

The hominin teeth found with Aldowan tools at Nyanga belong to the genus. ParanthropusIt is on a different human family tree than the one that leads to it Homo sapiens. Old tools were found together Paranthropus At other sites, including the Frida Leakey Korongo Zinge (FLK Zinge) site in Tanzania’s Olduvai Gorge Paranthropus Fossils have been found. At the time, paleoanthropologist Louis Leakey argued that the closest direct relative of humans had a slightly larger brain. Homo habilis, They must have made Oldowan tools. And one of the criteria for distinguishing humans from other apes provided the use of stone tools. But evidence from sites like Nyyanga is beginning to point to both. Paranthropus And H. Habilis Being a toolmaker. And the assemblages of macaques and capuchin monkeys suggest that the use of stone tools may have started much earlier in their evolutionary history than previously thought. Humans last shared a common ancestor 35 million years ago with capuchin monkeys and 25 million years ago with macaques, Luncz said. “I wonder if the use of stone tools is a very recent development in the hominin lineage,” she says.

Luncz and Proffitt hope to eventually figure out how primates are able to make the jump to picking up and using them by accidentally producing sharp blades. But for now, scientists can only speculate. Plummer points to a case where a group of hominins used rocks to break open the bones and access the nutrient-rich marrow when they found an animal carcass: In the process, one hominin missed the bone and knocked over a sharp splinter that had come loose from it. The stone he used. Then that hominin had the idea to use that fly to cut the meat off the carcass. “Hominins may be trying,” Plummer said.