Scientists unearthed a trove of 700-year-old stone tools — used by monkeys

New archaeological evidence suggests that Brazilian capuchin monkeys have been using stone tools to crack open nuts for at least 700 years. (Video: University of Oxford)

The sound can be heard from a distance. Bang, bang, bang! Clack, clack, clack!

Hairy little arms raise a stone, then bring it down with force on a cashew still in its sack of tough skin and toxic resin. The sound echoes as the stone smashes the nut on a bigger stone used as an anvil. A hungry capuchin monkey wants the meal contained inside.