In this 2014 photo made available by the journal Nature, a young bearded capuchin monkey strikes a stone against another in the Serra da Capivara National Park in Brazil. In a report released Wednesday, October 18, 2016, researchers say wild capuchin monkeys in Brazil deliberately break stones, unintentionally producing flakes similar to the ancient sharp-edged tools made by human ancestors. (Photo by Michael Haslam via AP Photo)
