Baboons seek “comfort” after deaths in the family
Courtesy University of Pennsylvania
and World Science staff
When a lion killed Sierra the baboon, her mother, Sylvia, responded in a way that one
could call very human-like: she looked to friends for support, say researchers who studied the animals.
The scientists found that baboons physiologically respond to bereavement in ways similar to humans, with an increase in stress hormones called
Baboons can lower their glucocorticoid levels through friendly social contact,
the researchers say. The animals do this by expanding their social network after the loss of specific close
“Our findings do not necessarily suggest that baboons experience grief like humans do,”
said Anne Engh, a postdoctoral researcher at the University of Pennsylvania in Philadelphia, one of the scientists.
“But they do offer evidence of the importance of social bonds amongst
baboons. Like humans, baboons seem to rely on friendly relationships to help them cope with stressful situations.”
At the time of Sierra’s death, Engh said, her team of researchers considered
her mother, Sylvia, to be “ the queen of mean. She is a very high-ranking, 23- year-old monkey who was, at best, disdainful of females other than Sierra,” Engh explained.
“With Sierra gone, Sylvia experienced what could only really be described as depression, corresponding with an increase in her glucocorticoid levels.”
Engh works with biologist Dorothy Cheney and psychologist Robert Seyfarth, also of the university. For the last 14 years, Cheney and Seyfarth have followed a troop of more than 80 free-ranging baboons in Botswana’s Okavango Delta.
Their research explores the mechanisms that might be the basis of primate social relationships and how such relationships may have influenced the development of human social relationships, intelligence and language.
To study the response of stress among baboons, Engh and her colleagues examined the glucocorticoid levels and grooming behavior of females in the troop to see how closely they resemble patterns seen in humans. Grooming, a friendly behavior in which baboons clean each other’s fur, is the main way for baboons to strengthen social bonds.
The team’s findings were published in a recent paper in the Proceedings of the
Royal Society of Biological Sciences, a research journal.
According to Engh, the death of a close family member clearly produced short-term
stress among female baboons. They studied seemed to compensate for the loss by broadening and strengthening their grooming
networks. As they resumed grooming, their glucocorticoid levels returned to normal.
“Without Sierra, Sylvia really had nobody else,” Engh said. Sierra had been not only her daughter but her closest grooming partner.
Sylvia’s depression was serious enough,
it seems, to make her give up her customary snobbery. “So great was her need for social bonding that Sylvia began grooming with a female of a much lower status, behavior that would otherwise be beneath
her,” Engh said.
Through her study, Engh tracked patterns in stress of the female baboons over time through their glucocorticoid levels. Stress levels increased most often during events when their lives, the lives of their offspring and their social rankings were at risk.
The leading cause of death among adult baboons is predation, usually from leopards and lions.
Female baboons’ stress levels increased most noticeably when a predator killed a close companion, such as a grooming partner or
offspring, the scientists said: if the baboons merely witnessed another baboon die, they
didn’t become as upset.
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