Just like human boys and girls, male monkeys like to play with toy cars while female monkeys prefer dolls.
The discovery is one of many signs of deep-rooted behavioural differences between the sexes that scientists are exploring with the latest tools of genetics and neuroscience.
Researchers report significant differences in the structure and functioning of male and female brains - in humans and in animals - that show up in different behaviours.
The differences apparently date far back in evolutionary history to the time before humans and monkeys separated from their common ancestor 25 million years ago, said Gerianne Alexander, a psychologist at Texas A&M University, who led the monkey experiment.
"Human evolution has created two different types of brains designed for equally intelligent behaviour," Richard Haier, a neuroscientist at the University of California at Irvine, wrote in the journal NeuroImage.
In the monkey experiment, researchers put a variety of toys in front of 44 male and 44 female vervets, a breed of small African monkey, and measured the amount of time they spent with each object.
Like little boys, some male monkeys moved a toy car along the ground. Like little girls, female monkeys closely inspected a doll's bottom. Males also played with balls while females fancied cooking pots. Both were interested in neutral objects such as a picture book and a stuffed dog.
People used to think that boys and girls played differently because of the way they were brought up. Now scientists such as Dr Alexander say a creature's genetic inheritance also plays an important role.