Monkeys could be even cleverer than we thought after scientists spotted them using tools in the jungle.
They studied capuchin monkeys in the Brazilian forest and saw them use stones to help dig up the ground and find things to eat.
Monkeys in zoos often use things to help them, but they've rarely been seen using them on their own in the wild.
Seeing the monkeys make their own tools in the jungle suggests they use them whenever they need to.
The monkeys were spotted using sticks and stones to crack open seeds and hollow branches, or for getting into places they can't reach on their own.
The scientists also think the monkeys only use tools when food is hard to find, like when there is no rain for a long time.
One of the scientists, Antonio Moura, told Science magazine he watched the monkeys using tools 154 times between October 2000 and March 2002.