Chimps May Mourn Lost Ones, Study Suggests

Two chimps living in captivity walk together

Some evidence from wild chimpanzee communities in Guinea suggests that when young chimps die, mothers continue to carry and groom them for some time. These two chimps live in captivity. iStockphoto.com hide caption

itoggle caption iStockphoto.com

A safari park in central Scotland may seem an unlikely place to plumb the meaning of life and death. But that's where animal behavior researchers managed to catch on videotape a rare glimpse of how chimpanzees respond to the illness and death of someone close to them.

The researchers, reporting in the April 27 issue of the scientific journal Current Biology, say their observation adds to the growing body of evidence suggesting that chimps have a rich emotional life.

"It might well be that they do have some awareness of death, which is more than what we previously suspected," says Jim Anderson, a psychologist and primate researcher at the University of Stirling, in Scotland. "We know from other work that chimpanzees, more than monkeys, are capable of showing empathy toward others who have a problem, or have been attacked. We see consolation behavior." Chimps clearly have a sense of self, he says, and some sense of future and past.

"They have all the pre-requisites," Anderson says, "for having some concept of death."

Quiet Deaths

But actually observing first hand how chimps respond to quiet deaths in their communities has been tough despite 50 years of study in the wild. Sick chimps often die alone in the forest, out of view. Even in the safari park in Stirling, the observations depended on remote video cameras that had been placed over the chimp sleeping platforms for another research project a year earlier. When an animal caretaker noticed that "Pansy," the elderly, dying matriarch of the small chimp troop was resting on one of the sleeping platforms late one afternoon, he turned the cameras on.

Chimpanzees romp in their home in the safari park. i i

Pansy and the three chimpanzees she lived with for decades romp in their home in the safari park. From left to right: Chippy, Blossom, Pansy, and her daughter, Rosie. Blair Drummond Safari Park hide caption

itoggle caption Blair Drummond Safari Park
Chimpanzees romp in their home in the safari park.

Pansy and the three chimpanzees she lived with for decades romp in their home in the safari park. From left to right: Chippy, Blossom, Pansy, and her daughter, Rosie.

Blair Drummond Safari Park

Because of that quick thinking, Anderson says, "we were able to record what happened on the night that this old chimpanzee female died in the midst of her group."

That night, the other three chimps, who had lived with Pansy for decades "seemed especially attentive to her," Anderson says. "More than on the previous few days, they were grooming her, they were caressing her. It just seemed to be a remarkable sign of caretaking towards her."

As the breathing of the old female chimp slowed, and finally stopped, the others bent down to look intently into her face. "We had never seen that before," Anderson says. They poked and gently shook her body for 30 or 40 seconds. They looked puzzled, he says, and slept more fitfully that night than usual. The dead chimp's adult daughter slept on the platform where her mother's body lay; close but not touching or inspecting it. The other two huddled together elsewhere, grooming each other more than usual. Once the body was removed the next day, the chimps avoided that platform for nearly a week. And for several weeks afterward, Anderson, says, the surviving chimps were "quite subdued."

Losing Young Chimps

Dora Biro, a zoologist at Oxford University who herself studies chimps, says she found the account fascinating. "It's an interesting question," she says, "to ponder the extent to which not just chimps, but any species of animal understands death."

Biro was studying a small colony of chimps in Bossou, Guinea in 2003 when a respiratory virus swept through, claiming the lives of five chimpanzees — including two infants. Next morning, when Biro and her team caught up with the troop, the mothers of the dead chimps did not seem subdued or distressed. They were just going about their business, she says, foraging and traveling with the group.

But there was one thing noteworthy: All the while, everywhere they went, and for a month or more afterward, they carried the limp and desiccated, decomposing corpses of their infants. What did that mean?

"It's such an obvious question that anybody who sees this will immediately ask," Biro says. "Why on earth do they do this? Don't they understand what happened? And honestly, I don't think we can say. I just don't know what they're thinking." Her account of the experience appears in the same issue of Current Biology.

The Roots Of Emotion?

Michael Wilson, a primatologist at the University of Minnesota, agrees with Anderson and Biro that it's important not to anthropomorphize — project human experience on any other species. Still, even if we can't peer into an animal's mind, he says, there is good evidence that emotion has deep evolutionary roots.

"Things like grief, a sense of loss, a difficulty in understanding that this person is really gone — it seems reasonable to think that these sorts of emotions are shared widely," Wilson says, "by other animals like chimpanzees and other primates, elephants, and many other animals, especially mammals."

He notes that chimps living in captivity don't have to worry about foraging for food, or keeping an eye out for predators. Maybe, he says, they simply have more time than chimpanzees in the wild to pay attention to what they've lost. Maybe they just have more time to grieve.

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