Chimps live in a male-dominated society, where most of their valuable partners are other males. However, as young male chimps become adults, they continue to maintain tight bonds with their mothers, a new study finds.

“The dramatic changes of adolescence are difficult for chimps, just like they are for humans,” says Elizabeth Lonsdorf, an expert on primates (灵长动物) at Franklin&Marshall College who was not involved in the study. “Sure enough,” she adds, “their moms remain a key social partner during this time.”

Previous research has shown chimp mothers provide their sons with support that goes far beyond nursing. Young male chimps that are close with their moms grow bigger and have a greater chance of survival. What’s more, losing their mothers after weaning (断奶), but before age 12，gets in the way of the ability of young chimps to win other males and reproduce.

To see whether this bond extends later into life, researchers followed 29 adolescent (9 to 15 years old) and young adult (16 to 20 years old) male chimps at a research site in Kibale National Park in Uganda and observed them from a distance for 3 years. The team found that the young adult males spent less time with their mothers than the adolescents did—26% vs. 76%. As the male chimps grew older and more independent, they began to travel over wider ranges and spent more time away from their moms.

However, when these young adult males happened to be in the company of their mothers, they acted just like the adolescents. They groomed (梳理) their moms just as often and kept track of them. “Many mothers remained the males’ ‘best friends’ or ‘social partners’ they associated with most frequently,” says study co-leader Rachna Reddy from Harvard University.

Such persistent ties are also common in humans after sons leave their mothers and live on their own—especially in tough times, Reddy says. “We really feel what it’s like to not be able to see our mothers when we want to in tough times. The importance of those bonds in our lives and the comfort we get from them have deep evolutionary roots.”

【小题1】What do we know about Elizabeth Lonsdorf?

A．She is in favor of the new study’s finding.

B．She played a supporting role in the new study.

C．She did a different study on chimps’ adolescence before.

D．She thinks chimps actually live in a female-dominated society.

【小题2】What may happen when a male chimp loses its mother at 8?

A．It may be easier for it to produce babies.

B．It may be easier for it to interact with other chimps.

C．It may be tough for it to defeat other males.

D．It may be much more aggressive than other males.

【小题3】What did the researchers probably do during their study?

A．They took care of some motherless chimps.

B．They recorded the chimps’ social interaction.

C．They worked hard to win the chimps’ trust.

D．They limited the chimps’ range of movement.

【小题4】What does Reddy aim to do in the last paragraph?

A．To stress the purpose of the study.	B．To improve humans’ mother-son relationship.
C．To call on us to protect chimps.	D．To emphasize the significance of the study.