From The New York Times:
Young female chimpanzees like to play with sticks as if they were dolls, according to a new study in the journal Current Biology. Although both juvenile male and female chimpanzees were seen playing with sticks in Kibale National Park in Uganda, females were more likely to cradle the sticks and treat them like infants. In human children, societal stereotypes may dictate what boys and girls play with, said Sonya Kahlenberg, a biologist at Bates College in Maine and one of the study’s authors. “The monkeys tell us there is something different there,” she said. The researchers studied juvenile behavior in a single chimpanzee colony over 14 years, and observed 15 females and 16 males.
Of the 15 females, 10 carried around sticks, while five of the males were seen with sticks. The young females were apparently mimicking their mothers, she said. “Females are the main caretakers,” Dr. Kahlenberg said. “Though it’s not that we didn’t see that in male chimps at all.” In one instance, an eight-year-old male with a stick stepped out of his mother’s nest, built a smaller nest and laid his stick in it. Although adult chimpanzees are also known to use sticks, they use them as foraging tools, not toys. Juveniles were defined as chimpanzees between the ages of five and 7.9. This is roughly equivalent to the human age range of six to nine, Dr. Kahlenberg said.