American psychologists say that they have found male monkeys to prefer boys' toys in a study.
Kim Wallen, a psychologist at Yerkes National Primate Research Center in Atlanta, says that the new finding hints that males, whether human or monkey, may have a biological predisposition to certain toys.
His team observed 11 male and 23 female rhesus monkeys during the study.
The researchers found that the males generally preferred playing with wheeled toys like dumper trucks, rather than plush dolls. Female monkeys, on the other hand, played with both kinds of toys.
Wallen revealed that rhesus monkeys were chosen for the study because social pressures would not determine their choices, as happens in the case of human subjects.
Most of the study animals were one to four years old juvenile, but some sub-adult and adult monkeys were included.
"They are not subject to advertising. They are not subject to parental encouragement, they are not subject to peer chastisement," New Scientist quoted Wallen as saying.
The monkeys were offered two categories of toys—"wheeled" like wagons and vehicles and "plush" like Winnie the Pooh and Raggedy-Ann dolls. Two toys, one wheeled and one plush, were placed 10 metres apart.
Initially, the monkeys formed a circle around a toy, and later one would snatch the toy and run off. Other monkeys soon joined in the play session, which was captured on video by the researchers.
Observing the video carefully, the researchers found that the males spent more time playing with wheeled toys, while the females played with both plush and wheeled toys equally.
Even though the plush and wheeled categories served as proxies for feminine and masculine, Wallen admits that other toy characteristics like size or colour might explain the male's behaviour. Or the male monkeys might seek out more physically active toys, he says.
However, there are researchers who believe that biological differences between sexes start the ball rolling toward learned preferences for play toys.
"There is likely to be a biological tendency that is amplified by society," says Gerianne Alexander, a psychologist at Texas A&M University in College Station.
Wallen's findings have been reported in the journal Hormones and Behavior.