Personality is known to shape human health and even influence the risk of earlier death. People who live long and fruitful lives tend to be gregarious, agreeable, conscientious, open-minded and emotionally stable. The reasons behind the link between personality and health outcomes, and the time at which it evolved, is as of yet unclear. But a recent study published in the Proceedings of the Royal Society B: Biological Sciences identified intriguing similarities in a closely related species, the gorilla – yet with an unexpected twist.
Researchers found that as with humans, extraverted gorillas led substantially longer lives despite differences in age, sex or living conditions. Extraversion in both humans and gorillas may lead to tight social relationships within family groups that shield individuals from external threats, thereby lengthening survival. Extraversion likely created these benefits even in the common ancestor shared by humans and gorillas more than 10 million years ago.
However, when researchers tested other characteristics such as agreeableness, neuroticism and dominance, they surprisingly found little connection to lifespan. Since these traits benefit human survival, their role in buffering against environmental stressors may have evolved in apes after humans split from gorillas.
To investigate the role of personality in survival, researchers from the University of Edinburgh, Zoo Atlanta and The Dian Fossey Gorilla Fund International examined 283 captive gorillas whose character traits had been rated by zoo keepers in 1993. Using gorilla studbooks to track survivorship, the researchers investigated associations between the animal’s personalities and the length of their lives. They also examined whether other factors such as sex, age, origin (wild- or captive-born), rearing conditions and number of institutional transfers affected survival.
The fact that characteristics of friendliness and sociability lengthen the lifespan of both humans and gorillas indicates that extraversion has been a favored personality trait for more than 10 million years. Social interactions may have thus played a critical role in shielding individuals from environmental stressors throughout time. It appears that the secret to a long life is no longer the fountain of youth, but rather a few new friends.