Programming, not social conditioning is responsible for girls loving dolls and boys being obsessed with guns, claims a new study.
Scientists have found that young chimpanzees in the wild play both boy and girl games, much like their human counterparts.
They found that although both male and female chimps play with sticks, girl chimps treat sticks like dolls imitating their mothers as they care for infants.
The findings have suggested that girls play more with dolls than boys not because of sex-stereotyped socialization but because of 'biological predilections.'
"This is the first evidence of an animal species in the wild in which object play differs between males and females," said Richard Wrangham of Harvard University.
Previous studies on captive monkeys had also suggested a biological influence on toy choice.
After 14 years of observation of the Kanyawara chimpanzee community in Kibale National Park, Uganda, researchers had found that chimpanzees use sticks in four main ways.
As probes to investigate holes potentially containing water or honey, as props or weapons in aggressive encounters, during solitary or social play, and in behaviour the researchers refer to as stick carrying.
"We thought that if the sticks are being treated like dolls, females would carry sticks more than males do and should stop carrying sticks when they have their own babies.
'We now know that both of these points are correct," said Wrangham.
Meanwhile, scientists are not sure whether stick-carrying was a form of play for all chimp clans or was just a 'social tradition that has sprung up' in the study group.
'This would suggest that chimpanzee behavioural traditions are even more like those in humans than previously thought," added Wrangham.
The findings were published in the journal Current Biology.