Pansy the morning after she died (Picture credit: Nicola McCleery, Blair Drummond Safari Park)

New Delhi, April 26: As 50-year-old Pansy drifted towards a peaceful death, her 20-year-old daughter Rosie spent the night tending to her. Minutes before Pansy died, others arrived and caressed her several times.

At the moment of her death, an acquaintance examined her body for signs of life. The next morning, Rosie and the others cleaned Pansy’s body. For weeks afterwards, they showed signs of grief and mourning.

Their actions were similar to human responses to death — but Pansy was a chimpanzee at the Blair Drummond Safari Park in Scotland where she died in an indoor enclosure in the presence of her daughter and two other chimpanzees.

Scientists have for the first time observed behavioural responses to death in chimpanzees that show striking similarities to human responses to the death of a close relative.

The observations have given rise to speculation that chimpanzees have far greater awareness of death than has been presumed by researchers until now.

“What we saw surprised us, and moved us,” said James Anderson, a psychologist at the University of Stirling, Scotland, who had led the research team that observed Pansy and her companions.

“As far as we know, humans are the only species with ritualised ways of dealing with dead members of their group,” Anderson told The Telegraph. The study findings will appear in the journal Current Biology tomorrow.

Wildlife biologists have previously observed chimpanzee mothers carrying dead infants for several days or weeks. Some scientists have seen chimpanzees show aggressive behaviour and hooting after traumatic deaths of adults — such as from falling off a tree.

But, Anderson and his colleagues said, how chimpanzees respond to the peaceful deaths of ageing chimpanzees in the wild is completely unknown.

Scientists say it is possible chimpanzees in the wild are under constraints that might drive them to abandon a dead member -- either to forage for food or to avoid falling prey to predators.

“But our observations certainly raise the possibility that once some constraints are removed... certain types of behaviour that we see in humans might be more likely to emerge,” Anderson said.

An animal behaviour scientist at the Indian Institute of Science Education and Research, Calcutta, not associated with this study, has called for caution in interpreting the observations.

“These findings appear interesting -- but they should not be used to conclude that chimpanzees and humans show similar responses to death,” said Anindita Bhadra, a fellow at the IISER’s behaviour and ecology laboratory.

“A single group of chimpanzees in a laboratory cannot be compared with human society. But this could be a starting point for more systematic studies of chimpanzees in the wild -- which are more difficult to do,” Bhadra said.

Anderson concedes there is still no way of knowing how typical the reactions displayed by Pansy’s daughter and her two companions were for chimpanzees.

But the calm behaviour of the chimpanzees in the enclosure is in sharp contrast to the frenzied, noisy responses observed in the past in the wild, Anderson said.

In some of the chimpanzee actions, the researchers recalled parallels from human behaviour. They have captured the chimpanzee responses on video and documented them in their paper.

In Pansy’s final days, they report in their paper, the other chimpanzees were quiet and attentive, showing signs of respect, care and even anticipatory grief.

On the night that she died, her daughter Rosie stayed with her on a night-long vigil, stroking and grooming Pansy’s torso. Another female adult groomed her arm.

At the moment of her death, the chimpanzees appeared to test for signs of life by inspecting her mouth and limbs for movement.

Rosie and the two other chimpanzees in the enclosure removed straw from Pansy’s body the morning after her death — an act that researchers describe as cleaning.

For weeks after her death, the three chimpanzees remained lethargic and quiet, ate less than normal, showing signs of grief and mourning.

The findings, Anderson said, suggest that chimpanzees have a highly developed awareness of death.