Humans might have learned how to eat cashews by observing monkeys, according to a new study which found evidence that Brazilian capuchins have been using stone tools to crack open the nuts for at least 700 years.
Researchers from Oxford University in the UK and University of Sao Paulo in Brazil observed groups of modern capuchins at Serra da Capivara National Park in northeast Brazil, and combined this with archaeological data from the same site.
They watched wild capuchins use stones as hand-held hammers and anvils to pound open hard foods such as seeds and cashew nuts, with young monkeys learning from older ones how to do the same. The capuchins created what researchers describe as ‘recognisable cashew processing sites’, leaving stone tools in piles at specific places like the base of cashew trees or on tree branches after use.