Gorillas mourn friends and strangers alike
Observers note similar responses towards in-group and out-group deaths. Andrew Masterson reports.
Gorillas spend time sitting with dead species members, sometimes grooming them, regardless of whether the deceased was a part of their group, researchers have found.
In a paper published in the journal PeerJ, scientists led by Amy Porter of the Dian Fossey Gorilla Fund International, in Georgia, US, report on the response of mountain gorillas (Gorilla beringei beringei) to the death of two senior members of their group. They also observe reactions of Grauer’s gorillas (Gorilla b. graueri) to the death of an unaffiliated male.
The researchers predicted that the in-group deaths – of a dominant male and female, both elderly, in the Volcanoes National Park in Rwanda – would elicit more reaction from others than the third death, that of an elderly male who was not a member of the local group.
They found, however, that responses were very similar.
In the case of the Volcanoes National Park deaths, of a male called Titus and a female called Tuck, from diseases associated with old age, younger gorillas who had been close to them spent the most time with the corpses.
A young male who had been cared for by Titus after his mother left the group was observed staying next to the body for two days, even sleeping next to it. One of Tuck’s sons groomed the body and, despite being long-weaned, attempted to suckle from the body – a behaviour Porter and colleagues suggest represents distress.
Males, both fully adult and juvenile, spent considerable amounts of time next to the body of the unaffiliated Grauer’s gorilla, sometimes grooming it. Notably, the researchers report, females did not come near it.
Porter and colleagues suggest that the responses to all three deaths were “influenced in part by close social relationships between the deceased and certain group members and by a general curiosity about death”.