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hards of stone produced by long-tailed macaques in Thailand’s Ao Phang-Nga National Park bear a striking resemblance to those found in some of the earliest archaeological sites in East Africa, according to researchers at the Max Planck Institute for Evolutionary Anthropology.
The monkeys use rudimentary stone tools, like a hammer and anvil, to crack open nuts. In the process, shards of stone flake off and are left behind. Although the monkeys haven’t been observed using them, the shards are similar in size and shape to those unearthed from early human settlements.