Chimpanzee Study Points to Difference in Learning Between the Sexes
A new study of chimpanzees at the Gombe Stream Research Centre, Tanzania, shows consistent and striking differences in the ways young females and males learn a critical behavior – fishing for termites. The study is an exciting contribution to the Centre’s ongoing research into the development of cultural behavior among wild chimpanzees.
The four-year longitudinal field study by scientists at JGI’s Center for Primate Studies shows that females learn to fish termites from mounds earlier, become more proficient termite fishers, and individually use techniques similar to their mothers’. Females also spend more time fishing while at the mounds with their mothers, whereas males spend more time playing.
The study is described in the April 15, 2004 edition of Nature. It was conducted by Dr. Elizabeth Lonsdorf, Dr. Anne Pusey, director of primate research for the Institute, and Dr. Lynn Eberly.
To study the chimpanzee learning patterns, Lonsdorf videotaped 14 chimpanzees (all under the age of 11) and their mothers during termite fishing sessions. She found that the females termite-fished when they were, on average, 27 months younger than male offspring. She also found they extracted a greater number of termites per dip than males.
Dr. Goodall said she was not surprised by Lonsdorf’s findings, which mirror her own observations. The study is the first detailed video analysis of Gombe chimp behavior. Another interesting aspect of the new research is that it demonstrates chimpanzees learning by imitation. The adult females studied each had quite distinct patterns of using short, medium and long fishing tools to varying degrees. The lengths of tool used by daughters greatly resembled their mothers’ choices, whereas the sons’ did not. “Obviously they are paying attention to their mother’s technique, while the sons are not,” said Pusey.
The difference in tool-use learning between females and males can be viewed in light of later differences in food acquisition patterns, said Pusey. Females fish for termites throughout the year, while males do it more seasonally. Termites are a more important source of protein for adult females, who do not hunt as much as males. Females occasionally hunt, but it is not a practical activity for them, as usually they are either pregnant or raising young.
The study should not be taken to mean the males are incapable of learning or imitating detailed behaviors, said Pusey. “It would be interesting to explore whether young males imitate the details of, say, adult male display behavior,” she said.