Having an extrovert personality could help you live longer, an international study of gorilla behaviour suggests.
Several theories exist about why there is an apparent link between the two, but one possibility is that being good at social interaction could act as a buffer against the effects of stress. Another theory is that extroversion indicates that an individual has a good immune system.
An international team of researchers, led by the University of Edinburgh, studied almost 300 gorillas in zoos and sanctuaries in the United States over 18 years.
The animals' personalities were assessed by keepers, volunteers, researchers and caretakers who knew the gorillas well. Particular attention was paid to four personality traits: dominance, extroversion, neuroticism and agreeableness.
Of the four traits, extroversion, associated with sociability, activity, play and curiosity, is linked with longer survival, the study concludes.
The connection between extroversion and survival was not affected by age or gender, rearing condition or how many times the gorilla moved location, it said. The findings are consistent with studies in humans, in that extroverts tend to live longer, researchers said.
Dr Alex Weiss, of the university's school of philosophy, psychology and language sciences, said: "The research that has been done suggests that extroversion, or at least certain aspects of extroversion in humans, are associated with lower mortality risk."
Asked about the possible reasons behind the findings, he said: "One possibility is that having a heightened amount of social interaction may buffer individuals from the effects of stresses.
"It may be that extroversion in gorillas, and possibly extroversion in humans, is some kind of a marker for a better immune system. There is actual evidence to that effect coming out of the California National Primate Research Centre. It shows that more sociable individuals seem to have immune systems that deal with infection better.
"It may also be the case that the genes that are associated with longevity are associated with extroversion. There are a lot of different possibilities and one or more of them may be at play here."