Monkeys in Brazil routinely use stones and twigs to forage for food, providing more evidence to undermine the belief that man is the only species with the intelligence to make tools.
Scientists have documented the daily use of tools by capuchin monkeys living in the harsh environment of the forestsof the Brazilian northeast.
The monkeys were photographed using stones to dig out vegetable tubers from the ground and for cracking nuts on a wooden anvil, as well as twigs for probing crevices for honey or insects.
It is the first time monkeys in the wild have shown they can find, fashion and use tools for foraging, although it is well documented in chimpanzees, a member of the great ape family.
Antonio Moura and Phyllis Lee, of Cambridge University, filmed the capuchin monkeys in Brazil's Caatinga Forest, where there is a marked dry season in the summer months and erratic rainfall for the rest of the year.
Several troops of monkeys routinely used stones to dig for food - something not observed even in chimps - and would often bring the rocks from one area to another, the scientists said.
"Monkeys typically held the stone with one hand and hit the ground quickly three to six times while simultaneously scooping away the soil with the other hand; they released the stone to dig with both hands or reused the stone again," they say in a study published in the journal Science.
Dr Moura, who has lived in this region of Brazil, said he became interested in capuchin monkeys because they seemed to thrive in an area that was renown for its aridity.
"Locals would often talk about how clever the monkeys were at cracking seeds."
