Capuchin monkeys stone-tool use has evolved over 3,000 years

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Excavations in Brazil have pounded out new insights into the handiness of ancient monkeys.

South American capuchin monkeys have not only hammered and dug with carefully chosen stones for the last 3,000 years, but also have selected pounding tools of varying sizes and weights along the way.

Capuchin stone implements recovered at a site in northeastern Brazil display signs of shifts during the last three millennia between a focus on dealing with either relatively small, soft foods or larger, hard-shelled edibles, researchers report. These discoveries, described online June 24 in Nature Ecology & Evolution, are the first evidence of changing patterns of stone-tool use in a nonhuman primate.

“Its likely that local vegetation changes after 3,000 years ago led to changes in capuchin stone tools,” says archaeologist Tomos Proffitt of University College London. The new findings raise the possibility that chimpanzees and macaque monkeys, which also use stones to pound and dig, have shifted their tool-use styles over the long haul, perhaps in response to climate and habitat changes, Proffitt says.

Archaeological sites linked to apes and monkeys are rare, though. Previous excavations in West Africa unearthed nut-cracking stones wielded by chimps around 4,300 years ago (SN: 11/21/09, p. 24). Present-day chimps inhabiting the same part of Africa crack nuts with similar-looking rocks.

Evidence of long-term changes in tools used by wild capuchins (Sapajus libidinosus) comes from a site in Brazils Serra da Capivara National Park. Excavations there have also yielded ancient human stone tools (SN: 10/18/14, p. 14). But the newly unearthed artifacts more closely resemble stone tools used by modern capuchins at the same site (SN: 11/26/16, p. 16), rather than Stone Age human implements, the researchers say.

Primatologist Tiago Falótico of the University of São Paulo, Proffitt and their colleagues recovered 122 capuchin stone artifacts from four sediment layers. Radiocarbon dating of charred wood bits in each layer provided age estimates for the finds. Excavated tools consisted of partial and complete pounding stones, rocks used as platforms on which to pound objects, and pieces of rock that detached from pounding stones and platforms during use.

Relatively small, heavily damaged pounding implements from between around 3,000 and 2,500 years ago were likely used to smash open tiny foods such as seeds or fruits with soft rinds, the researchers say. Similar tools uncovered at the site date to around 600 years ago. Larger pounding stones from overlying sediment appeared about 300 years ago. The appearance of bigger capuchin tools by around that time denoted a shift to eating hard-shelled fruits and nuts that required higRead More – Source

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