Female chimpanzees are more negative when communicating with those of the same gender, a new study has found. The study analysed the different gesturing strategies used by a group of females at Chester Zoo.
In female-female interactions, the chimps used more aggressive signals and apologised less often with gestures of reassurance. But they employed a more positive strategy around males, with more expressions of greeting and submission.
When communicating with males, females sort of suck up to them, PhD student Nicole Scott from the University of Minnesota, Minneapolis, said. To carry out the research, Scott video-recorded the behaviour of 17 females and five males in a group of chimps at Chester Zoo, UK.
"I defined gesture as an expressive movement of the limbs or head and body postures produced intentionally," she told BBC Nature. Examination of overall behaviour in males and females showed no differences in the repertoire of gestures the animals used. But differences in communication appeared when individual interactions were analysed.
While females in the group adopted a different gesture strategy depending on the sex of a partner, the males did not. Scott suggests that this indicates that female chimpanzees are more sensitive to the sex of their partner than males, and cater their gesture use accordingly.
According to the biologist, different social pressures on the sexes could explain the difference in communication strategies. For example, males might have more positive relationships with other males because of the importance of male-male alliances and maintaining high social rank in a group. But there may be less focus on female chimpanzees maintaining multiple, positive relationships with other females, and instead more pressure on them to form positive relationships with males.
The findings are published in the American Journal of Primatology.