阅读理解。 Scientists at Harvard University

问题：

阅读理解。

     Scientists at Harvard University and Bates College find female chimpanzees (黑猩猩) appear to

treat sticks as dolls, carrying them around until they have children of their own. Young males engage

in such behavior much less frequently.

     The new work by Sonya M. Kahlenberg and Richard W. Wrangham, described this week in the

journal Current Biology, provides the first evidence of a wild nonhuman species playing with dolls, as

well as the first known sex difference in a wild animal's choice of playthings.

     The two researchers say their work adds to a growing body of evidence that human children are

probably born with their own ideas of how they want to behave, rather than simply mirroring other

girls who play with dolls and boys who play with trucks. Doll play among humans could have its origins

in object-carrying by earlier apes (猿类), they say, suggesting that toy selection is probably not due

entirely to socialization.

     "In humans, there are obvious sex differences in children's toy play, and these are remarkably similar

across cultures," says Kahlenberg. "While socialization by elders and peers has been the primary

explanation, our work suggests that biology may also have an important role to play in activity

preferences."

     In 14 years of data on chimpanzee behavior at the Kibale National Park in Uganda, Kahlenberg

and Wrangham counted more than 100 examples of stickcarrying. Some young chimpanzees carried

sticks into the nest to sleep with them and on one occasion built a separate nest for the stick. "We have

seen juveniles occasionally carrying sticks for many years, and because they sometimes treated them

rather like dolls, we wanted to know if in general this behavior tended to represent something like

playing with dolls," says Wrangham, a Professor at Harvard. "If the doll hypothesis (假设) was right,

we thought that females should carry sticks more than males do, and that the chimpanzees should stop

carrying sticks when they had their first child. We have now watched enough young chimpanzees to

prove both points."

1. What does a female chimpanzee do with sticks?

A. She gives them to her child to play with.  

B. She treats them as dolls.

C. She makes useful tools from them.  

D. She treats them as weapons.

2. What causes the different toy selection of chimpanzees, according to the passage?

A. Sex difference.  

B. Socialization.

C. Environment.

D. Cultural difference.

3. We can infer from the fourth paragraph that ________.

A. socialization has nothing to do with human's choice of playthings

B. sex difference is the only factor in human's choice of playthings

C. the biology factor may also influence toy choice

D. people choose different toys in different cultures

4. It can be concluded from the passage that ________.

A. both humans and chimpanzees choose their playthings due to sex difference

B. different factors cause humans and chimpanzees to choose different playthings

C. only female chimpanzees have playthings

D. chimpanzees usually choose playthings for their children