Monkeys smash stone tool theories

by Mary Caperton Morton
Tuesday, January 17, 2017

Archaeologists have long credited stone flakes found at dig sites to tool-making hominins, but observations of wild capuchin monkeys in Brazil breaking stones may put an end to the assumption that all stone flakes were made by humans and their ancestors.

Bearded capuchins in Serra da Capivara National Park in Brazil regularly smash stones together, possibly in an effort to eat minerals in the rocks. This “percussive behavior” inadvertently produces flakes that are not used by the monkeys for any further purpose. But when the flakes were examined by Tomos Proffitt, an archaeologist at the University of Oxford in England, and colleagues, they found that about half the flakes showed conchoidal fractures — a pattern associated with tool production by Homo sapiens alone in South America (elsewhere, other members of the Homo genus, like H. habilis, are also associated with stone flakes). The researchers reported the findings in Nature.

“This does not mean that the earliest archaeological material in East Africa was not made by hominins,” Proffitt said in a statement. “It does, however, raise interesting questions about the possible ways this stone tool technology developed before the earliest examples in the archaeological record appeared.” Additionally, he said, “these findings challenge previous ideas about the minimum level of cognitive and morphological complexity required to produce numerous conchoidal flakes.”

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