Chimpanzees deal with death in much the same way as humans, studies suggest.
Scientists in Scotland filmed a group of chimps grooming and caressing an elderly female who died, and remaining subdued for several days afterwards.
Other researchers saw females carrying around the bodies of their dead offspring. Both studies are reported in the journal Current Biology.
The scientists say this suggests other species, particularly apes, are more like humans than we might think.
We found several similarities between the chimpanzees' behaviour toward the dying female and their behaviour after her death, and some reactions of humans
James Anderson Stirling University
"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," said James Anderson from Stirling University, who led the research team looking at the death of the elderly female.
"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.
"The awareness of death is another such psychological phenomenon."
Staff at Blair Drummond Safari and Adventure Park in Stirlingshire used video cameras to document the death of a terminally ill female named Pansy, believed to be more than 50 years old.
When she became lethargic in the days leading up to her death, other members of the group became quieter than usual and stayed with her at nights, grooming her more than they did normally.
After her death, her daughter stayed near the body for an entire night, even though she had never slept on that platform before.
All of the group were subdued for several days afterwards, and avoided the place where she had died, spending long hours grooming each other.
A young chimp plays with the mummified corpse of an infant, before the dead chimp's mother retrieves it
In the second study, led by scientists at Oxford University, two mothers living in the wild at the Bossou site in Guinea were seen to carry around the bodies of their dead offspring - one of them for nearly 10 weeks.
This behaviour has been seen once before at the site, in 1992; and the researchers suggest it may be learned.
During the period, the babies' bodies slowly mummified as they dried out. The bereaved mothers used tools to fend off flies.
"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," said Oxford's Dora Biro.
"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.
"This would both have implications for our understanding of the evolutionary origins of human perceptions of death and provide insights into the way chimpanzees interpret the world around them."
Chimpanzees and humans share about 99% of their DNA, and are so closely related that some academics have suggested they should be given rights similar to human rights.
Dr Anderson suggests the treatment of death marks another similarity.
"We found several similarities between the chimpanzees' behaviour toward the dying female and their behaviour 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," he said.
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