Stone flakes made by monkeys cast doubt on ancient human ‘tools’

By using stones to crack the nuts, the monkeys accidentally create spiky flakes that look like tools believed to have been used by their ancient human relatives.

The find raises questions about whether all the stone flakes found in archaeological excavations were indeed tools of early humans, and could be an accidental by-product of whole stone bashing. , says Lydia Lantz of the Max Planck Institute. Evolutionary Anthropology, Leipzig, Germany.

In 2016, Luncz and her colleagues noticed that capuchin monkeys in Brazil produce stone flakes from rocks to pound, dig and engage in sexual displays of food, not necessarily unintentionally. The flakes were essentially identical to those found in hominin settlements at least 3 million years old. The team wondered if the artifacts really reflected the technological plans of early humans.

Since then, Luncz and her colleagues have studied tool use in cercopithecus (Macaca fascicularis) islands of Phang Nga Bay in Thailand. In the woods there, Luncz stumbled upon a place to crack nuts. He was surprised because until now cercopithecuses were not known to crack nuts.

The team installed motion-activated cameras to study the behavior of macaques in the wild. In his 100 hours of footage, the team shows a monkey knocking a nut between his two stones, which act as a hammerstone and an anvil, accidentally creating flakes, leaving the broken stone behind to create a new, perfect stone. I witnessed finding the

This is pretty much what capuchin monkeys did in previous studies, Luncz said, and shows that flake production isn’t a one-time thing. “This was happening on the other side of the globe, in a different ecosystem and a different species,” she says. “So it was clear that this was from a primate, a foraging behavior that was also seen in early hominins.”

So far, capuchin monkeys, chimpanzees and cercopithecus are the only non-human primates known to use stone tools in the wild, and all of these have accidentally produced flakes that appear to be tools of ancient humans. It has now been proven to generate

The team then compared 1,119 stone flakes from macaque nut-cracking sites to artifacts found at hominin sites in Ethiopia, Kenya, and Tanzania. According to Tomos Profit, another member of the research team, the thin, flat, broad stone fragments of monkeys ranged in length from 1.3 to 7.9 centimeters and were dated to ancient humans up to 3.3 million years ago. It was “almost indistinguishable” from the stone fragments associated with the At the Max Planck Institute for Evolutionary Anthropology.

Although some different trends were observed, for example, monkey flakes were on average smaller and thicker than hominin flakes, but were still very similar, making it the largest of ancient human tools. It may have replaced 70%.

The discovery could challenge our current understanding of early stone technology, says Proffitt. “I wouldn’t say all of the old material was unintentional,” he says. “But what our research shows is that we can’t be 100% sure that every flake in the early Stone Age archaeological record was intentionally created. That record. may contain unintended components.”

For Zeray Amelseged of the University of Chicago, the study largely points to a gradual progression of cognitive evolution in primates. “Are what we find in the archaeological record just the result of a process rather than intentional?” he says. “I don’t think we have the answer, but the key point of this paper is that the behavior of stone tool making and stone tool use has a lot to do with the primate world, but also much more in time. It’s got a deep history, and it’s becoming clearer.”