London: Young female chimpanzees are smarter than males in object manipulation - seemingly in preparation for adult tool use - as they display greater diversity in manipulation, a study finds.
Although it was young males that spent more time manipulating objects, but much of this activity was dominated by 'play' with no apparent immediate goal, and often associated with a 'play face' - a relaxed expression of laughing or covering of upper teeth.
Immature females, on the other hand, showed lower rates of object manipulation, especially in play, but displayed a much greater diversity of manipulation types than males - such as biting, breaking or carrying objects - rather than the play-based repetition seen in the object manipulation of immature males.
This seems to prepare the females better for future tool use.
Notably, in adult wild chimpanzees females are more avid and competent tool users.
"We found that male chimpanzees showed higher object manipulation rates than females, but their object manipulation was dominated by play. Young female chimpanzees showed much more diverse object manipulation types," said lead author Kathelijne Koops from the University of Cambridge.
The sex bias for object manipulation the researchers found in juvenile chimpanzees is also found in human children.
"Immature females seem to focus their attention on relevant tool use related tasks and thus learn quicker, whereas males seem to do more undirected exploration in play," the researchers observed.
The study also found that young chimpanzees showed higher rates and, importantly, more diverse types of object manipulation than bonobos.
"Despite being so closely related on the evolutionary tree, as well as to us, these species differ hugely in the way they use tools, and clues about the origins of human tool mastery could lie in the gulf between chimpanzees and bonobos," Koops said.
The study appeared in the journal PLOS ONE.