for National Geographic News
Sylvia, a 23-year-old baboon living in the Okavango Delta of Botswana, Africa, is one of the highest-ranking members of her troop.
In the past, she generally expressed nothing but contempt for other troop members, except for Sierra, her grooming companion.
But when Sierra was killed by a lion, Sylvia went into what could be described as mourning. She then appeared to seek solace in the form of mutual grooming from females whom she had previously seemed to consider beneath her attention.
Researchers working with Sylvia's troop now say they have physical evidence that Sylviaand other female baboonsexperience grief.
"In general, female baboons have closer relationships than males do," said Anne L. Engh, a postdoctoral researcher in biology at the University of Pennsylvania in University Park.
"Male baboons don't cooperate socially and don't form friendships with each other. So I wouldn't expect them to mount much of a stress response to the demise of another male," said Engh, who was the lead author on the study.
In addition to observing differences in behavior, the scientists measured the levels of stress hormones in female baboons' feces.
They found that females who had lost a close relative showed significantly higher levels of the stress hormone glucocorticoid than unaffected animals in the same reproductive state.
What's more, seeking companionship after the loss seemed to lower the grieving animals' glucocorticoid levels back to normal levels.
Engh and colleagues report the findings in a recent issue of the journal Proceedings of the Royal Society B.
"Queen of Mean"
According to Engh, Sierra was Sylvia's daughter, "and Sylvia usually didn't interact with other females. If she did, she wasn't very friendly." (Wallpaper: mother baboon and child.)
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