Even Monkeys Know Which Rock Will Break the Toughest Nut

Capuchin monkeys not only have the capacity to use tools, they also know which tool is best for the job at hand, according to a new study. Researchers observed capuchin monkeys in the wild testing out different stones and consistently settling on the heaviest, sturdiest stone to crack open palm nuts. Although anecdotal reports existed before, the new study is the first to systematically document tool use in capuchin monkeys.