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A primate primer: Boys will be boys, as girls ape mom Add to ...

The girls watch their mothers closely. The boys horse around. Researchers have found sex-based learning differences in chimpanzees that are similar to those observed in human children.

This means, the scientists said, that sex-based learning differences likely have a biological basis that dates back to the last common ancestor of humans and chimpanzees.

University of Minnesota researcher Elizabeth Lonsdorf spent four years videotaping 14 young chimps in Gombe National Park in Tanzania as they learned how to fish for termites.

This involves poking flexible twigs, grass or other tools into termite mounds. The insects the chimps extract are a good source of protein.

The young females spent more time than young males intently watching their mothers fish for termites, and became proficient at it at when much younger than the males; they spent more time playing and swinging around the mounds.

"In human children, studies have found that females are better at writing and drawing skills and skills requiring attention and planning. Males have been found to be better at gross motor skills, like running and jumping," Dr. Lonsdorf said.

"We determined that termite fishing is very similar to writing and drawing, as both are fine manual skills."

The young female chimps quickly learned the technique of mixing short dips with medium and long dips to reach termites at different depths. The young males did not catch on.

As a result, females were, on average, 27 months younger than males when they first obtained termites when using tools.

They were also better at it, getting more tasty insects per dip.

"To our knowledge, this is the first systematic evidence of a difference between the sexes in the learning or imitation of tool-use technique in wild chimpanzees," Dr. Lonsdorf and her colleagues wrote in the most recent edition of the British journal Nature, published today.

"A similar disparity in the ability of young males and females to learn skills has been demonstrated in human children, and may be indicative of different learning processes.

"A sex-based learning difference may therefore date back at least to the last common ancestor of chimpanzees and humans," Dr. Lonsdorf added.

It is believed that the evolutionary lines of humans and chimps diverged about five million to six million years ago.

Termite-fishing season for chimpanzees in Gombe is from October through December.

At peak season, males hunt for termites as often as females do. During the rest of the year, the males spend more time hunting for monkeys, also a source of protein.

Anne Pusey, a University of Minnesota primate researcher who worked with Dr. Lonsdorf on the study, said she does not think the young males are less interested in termite hunting because it is less important to them.

The study found that the sex-specific behaviours emerge at young age, about 31 months for the females and 58 months for the males.

"It appears to be biological," Dr. Pusey said.

Joel Kramer is a University of California scientist who has studied how girls and boys, and men and women, learn.

He said there is strong evidence that girls generally have much stronger verbal and language skills than boys, and that boys are slower to progress in those areas.

But boys are better at learning spatial skills, which are useful for interpreting maps, graphs and even X-rays.

Dr. Kramer said the male chimps in this study are exploring and developing their spatial skills when they are horsing around; when they grow up, those spatial skills may make them superior termite hunters.

Many researchers believe there is a biological basis for this; that female hormones, for example, may play a role in memory.

There is still debate, however, over whether biology or culture plays a larger role in the learning differences that have been observed between the sexes in humans.

 

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