People have wondered for years if little girls play with dolls and little boys play with cars because of the toys they are given or because of their instincts, so when a group of scientists observed a group of young chimpanzees playing in similar ways to human children they set out to find out if gender stereotypes in kids is the result of nature or nurture. Learn the surprising answer here. — Global Animal

Sydney Morning Herald, Nicky Phillips

It is the same around the world: given a choice of toys, young girls tend to play with dolls and young boys prefer pretend weapons and vehicles.

But research has found these characteristics may not be limited to humans. US scientists have presented evidence that young chimps also play differently according to their sex.

The findings suggest giving children sex-stereotyped toys is not the only influence on how they play. There may also be a biological component. 

Over 14 years the researchers observed a community of chimpanzees in the Kibale National Park in Uganda and found they used sticks for many purposes, including probing for water or honey, as weapons and for play. But female juveniles also carried around sticks in ways similar to young girls playing with dolls, a behaviour the researchers called play-mothering.

The primates could carry the sticks for up to four hours while sleeping, eating and climbing.

”Individuals rested and were sometimes seen to play casually with the stick in a manner that evoked maternal play,” said the authors, whose findings are published in the journal Current Biology. This was rarely observed in males.

”This is the first evidence of an animal species in the wild in which object play differs between males and females,” said a co-author, Richard Wrangham, an anthropologist, of Harvard University.

The researchers found that carrying the sticks stopped when the females become mothers. They believe the young chimps learnt the behaviour from their peers.

”Such juvenile traditions have previously been described only in humans,” the authors said.

They suggest female juveniles’ interest in stick-carrying stems, in part, from their innate interest in infant care.

In earlier studies on captive primates given stereotyped human toys, female monkeys played with more feminine toys and males with more masculine toys.

As the Kibale chimps are the first animal group to display such behaviour, it may be a unique trait, the first example of a tradition among young animals. Chimp behaviours could be ”even more like those in humans than previously thought”, Professor Wrangham said.