Sunday, May 02, 2010

Science Sunday: When It Comes To Death, Humans Are Very Chimp-Like

There have been a rash of reports and scientific studies lately asserting that chimpanzees and their brethren react to death very much like humans. That is ass backwards: The fact of the matter is that humans react to death very much like chimpanzees and their brethren.

This brings us to three stories in which the actions of chimps seem remarkably human:

The death of Dorothy, a chimp in her late 40s, of congestive heart failure in September 2008 at Sanaga-Yong Chimpanzee Rescue Center in Cameroon.

After a hunter killed her Dorothy's mother, she was sold as a "mascot" to an amusement park. For the next 25 years she was tethered to the ground by a chain around her neck, taunted, teased, and taught to drink beer and smoke cigarettes for sport.

In May 2000 Dorothy -- obese from poor diet and lack of exercise -- was rescued and relocated along with 10 other primates. As her health improved, her deep kindness surfaced. She mothered an orphaned chimp named Bouboule and became a close friend to many others, including Jacky, the group's alpha male, and Nama, another amusement-park refugee.

The Sanaga-Yong management opted to let Dorothy's chimpanzee family witness her burial, so that perhaps they would understand that Dorothy would not return. Some chimps displayed aggression while others barked in frustration. But perhaps the most stunning reaction was a recurring, almost tangible silence among creatures who usually are anything but.

* The death of Pansy, a 50-year-old chimp, in December 2008 on an island in Blair Drummond Safari Park in Scotland. At her side were three other chimps -- daughter Rosie, another adult female called Blossom, and Blossom’s son Chippie.

Pansy's fellow chimps seemed to sense that something was up when she had started becoming lethargic the previous month, and instead of sleeping on their usual platforms they nested near her. Their reaction to her passing was recorded by the park's cameras (video still, above right). The chimps seemed to care for her in her final minutes, examine her body for signs of life, and then avoid the place where she died. Rosie even conducted the equivalent of an all-night vigil.

* The deaths of five chimps in the forests of Bossou, Guinea in 2003 amidst a respiratory epidemic.

Two of the chimps were babies, Jimato and Veve, and their mothers, Jire and Vuavua, carried their babies' lifeless bodies around for 68 and 19 days respectively. They groomed the dead youngsters and chased away the flies that circled them, and even after the babies had completely mummified into dry, leathery husks, the mothers still carried them, and other groups members investigated them by poking and sniffing the bodies and lifting their immobile limbs.

* * * * *
Legendary primate researcher Frans de Waal is not surprised in the least by these stories.

"The carrying of dead infants by chimpanzee mothers is well known, and has also been reported for other primates, although never of such long duration," he says.

De Waal (photo, left) notes that ape physiology drives an enormous attachment between mother and infant that doesn’t disappear when the infant dies. As a consequence, a chimp's reproductive cycle stops for four years after giving birth.

"It would also not be adaptive to abandon an infant every time it gets sick," he explains. "The best option is for mothers to keep hope and keep caring. A rapid shutting down of attachment would be maladaptive: it might lead mothers of near-dead infants to abandon them prematurely."

Why then did Jire and Vuavua eventually let go? As their reproductive cycle restarted and all the associated hormonal changes kicked in, the mothers could have been psychologically prepared to raise another generation. The fact that Jire carried her dead child for longer than Vuavua may be because she had already had seven previous children, while Vuavua was a first-time mother.

All of these examples suggest that chimpanzees have a much greater awareness that people have previously thought, notes science writer Ed Yong (photo, above) But do chimps truly understand the concept of death? Based on these stories, the answer is most definitely yes.

No comments: