Chimps Sensitive to Companions’ Deaths

May 25, 2010 Updated: October 1, 2015

SENSITIVE ANIMAL: Research found that chimpanzees are sensitive to their companions' deaths.
SENSITIVE ANIMAL: Research found that chimpanzees are sensitive to their companions' deaths.
It is believed that only humans are emotional and sensitive to our loved ones’ deaths, yet two recent studies published in Current Biology have shown that chimps also have feelings of attachment and need time to “get over” their companions’ deaths.

In one case, researchers observed via video the final hours of an older female chimp in a small group of animals at a U.K. safari park.

“Several phenomena have at one time or another been considered as setting humans apart from other species: reasoning ability, language ability, tool use, cultural variation, and self-awareness, for example, but science has provided strong evidence that the boundaries between us and other species are nowhere near to being as clearly defined as many people used to think,” said Dr. James Anderson of the U.K.’s University of Stirling in a press release.

“The awareness of death is another such psychological phenomenon. The findings we’ve described, along with other observations of how chimpanzees respond to dead and dying companions, indicate that their awareness of death is probably more highly developed than is often suggested. It may be related to their sense of self-awareness, shown through phenomena such as self-recognition and empathy toward others.”

Historically, mother chimps have been known to carry their dead infants, said Anderson, but few people have had the chance to witness chimps’ response to the dying of their closest adults.

“In contrast to the frenzied, noisy responses to traumatic adult deaths, the chimpanzees witnessing the female’s death in our case were mostly calm,” he said.

In the final days before the chimp’s death, the group remained quiet and paid close attention to her, reported the researchers, according to the press release. Right before she died, others groomed and caressed her, probably testing her for signs of life. Upon her death, the group left her, but her adult daughter returned and stayed with her all night.

When the keepers removed the mother’s body the next day, the chimps remained calm. For several days, they avoided sleeping on the platform where the female had died even though it was previously a favored sleeping spot.

“In general, we found several similarities between the chimpanzees’ behavior toward the dying female, and their behavior after her death, and some reactions of humans when faced with the demise of an elderly group member or relative, even though chimpanzees do not have religious beliefs or rituals surrounding death,” Anderson said.

In another study, Dr. Dora Biro of the University of Oxford and her colleagues observed the death of five members—two of which were infants—of a semi-isolated chimp community that researchers have been studying for more than 30 years in the forests surrounding Bossou, Guinea.

“We observed the deaths of two young infants—both from a flu-like respiratory ailment,” Biro said according to the press release. “In each case, our observations showed a remarkable response by chimpanzee mothers to the death of their infants: They continued to carry the corpses for weeks, even months, following death.”

During that time, the corpses mummified completely. The mothers cared for the corpses as they would for live infants, such as grooming them, carrying them during the day, and taking them to their nests.

The mothers “let go” of the infants as they allowed other members in the group to handle them more and more. For example, live infants were allowed to carry off and play with the corpses.

“How they perceive death is a fascinating question,” said Biro. “And little data exist so far concerning chimpanzees’ responses to the passing of familiar or related individuals either in captivity or in the wild. Our observations confirm the existence of an extremely powerful bond between mothers and their offspring which can persist, remarkably, even after the death of the infant, and they further call for efforts to elucidate the extent to which chimpanzees understand and are affected by the death of a close relative or group-mate.”

To read the abstract of Anderson et al.’s research paper, “Pan thanatology,” please visit http://tinyurl.com/234oa5o

To read the abstract of Biro et al.’s research paper, “Chimpanzee mothers at Bossou, Guinea carry the mummified remains of their dead infants,” please visit http://tinyurl.com/2axoqhp

To see videos published with the two research papers, please visit http://www.cell.com/current-biology/Chimpanzee_movies