Like mother, like daughter

Young female chimps excel in tool use

A mother chimp and her daughter fishing for termites. U reasearch found that daughters copy their mothers' patterns exactly and learn the skill faster and better than their brothers--who are off learning their own survival skills.

By Deane Morrison

From M, summer 2004

Both female and male chimps learn from their mothers how to insert sticks into termite mounds and pull out a tasty meal of insects. But females learn earlier, spend more time at it, and tend to catch more termites with each try, according to a University of Minnesota study recently published in Nature. The distinct differences between sexes in learning this skill are akin to differences between young human females and males as they learn fine motor skills like writing, the researchers say. The study, done at Gombe National Park in Tanzania, is the first systematic evidence of a difference between male and female wild chimpanzees when it comes to learning or imitating tool use.

Because this learning difference is similar to differences in human learning, the findings imply that sex-based learning differences in humans have an ancient origin--a difference that may date back at least to the last common ancestor of chimpanzees and humans, the researchers say. According to current estimates, the evolutionary lines of humans and chimps split about five to six million years ago, says coauthor Anne Pusey, Distinguished McKnight University Professor in the Department of Ecology, Evolution, and Behavior.

Lynn Eberly, a biostatistician in the University's School of Public Health, was the third author of the study.

"This finding is a heads-up to researchers studying the learning of relatively complex skills [among humans] that they should take sex into account," said Elizabeth Lonsdorf, who headed the study as a graduate student at the University and is now director of field conservation at the Lincoln Park Zoo in Chicago.

Lonsdorf spent four years videotaping 14 young chimps under the age of 11 and their mothers. Each mother fashioned fishing tools from sticks, palm fronds, or grass and inserted them at varying depths into tunnels in termite mounds. Daughters copied their mothers' patterns exactly. For example, if a mother inserted her tools a short distance 80 percent of the time and medium or long distances each 10 percent of the time, her daughter did the same. Sons spent less time watching their mothers, and their termite-fishing patterns were completely unrelated to their mothers'.

While young females perfected the art of termite fishing, young males spent more time playing and swinging around--behaviors that may help them in typically male adult activities like hunting and struggling for dominance. And those activities make perfect sense for chimps.

"The availability of animal protein is limited for chimpanzees. They can fish for termites or hunt colobus monkeys," explains Lonsdorf. "Mature males often hunt monkeys up in the trees, but females are almost always either pregnant or burdened with a clinging infant. This makes hunting difficult. But termites are a rich source of protein and fat. Females can fish for termites and watch their offspring at the same time. Adult females spend more time fishing for termites than males do. The young of both sexes seem to pursue activities related to their adult sex roles at a very young age."

See a video of chimpanzee termite fishing.