A new study suggests that girls are as competitive as boys, but that their tactics are not as aggressive.
According to the research, boys use head-on aggression to get what they want, while girls rely on the pain of social exclusion.
To test the apparent differences in how very young children compete, Joyce Benenson at Emmanuel College in Boston, Massachusetts, US and her colleagues divided 87 four-year-olds into same-sex groups of three.
In successive trials, each trio received either one, two or three highly prized animal puppets.
The sexes behaved similarly when there were two or three puppets to go round. The differences became clear, though, when there was just one puppet for each group, reports New Scientist.
Boys tended to ask for the puppet, grab at it, or even chase the child who had it. In contrast, girls punished the puppet-holder by excluding her from their clique, whispering behind her back or even hiding from her.
Benenson says that these socially aggressive tactics may explain why girls exhibit greater jealousy over same-sex friendships than boys. They could be trying to protect themselves against exclusive coalitions.
Melissa Emery Thompson at the University of New Mexico in Albuquerque, also in the US, praises the study for creating "organic yet controlled situations in which the children's natural behaviour emerges spontaneously".
She says the results help to dispel the myth that females are the less competitive sex. Even at an early age, they avoid risky direct aggression in favour of subtler forms of competition, such as small shifts in tone and expression, or spreading rumours.
Emery Thompson says that these differences also explain why human males tend to cooperate more effectively in groups while many females "work well in pairs and tend to maintain only a few close relationships."
The study is published in the journal Animal Behavior.