Chimp seen cleaning her dead son's teeth, suggesting animals think about death

The research could tell us why we are so pre-occupied with our own mortality

Chimps have been seen engaging in "mortuary activity" for the first ever time, suggesting that animals think and even worry about death.

Scientists have reported watching a chimp clean her son's teeth after he died, the first time that animals have been seen behaving in that way. Almost all reports of animals using tools do so on their own – but the new study reports not just the social use of tools among chimpanzees, but using it in a very strange way.

The two chimps were mother and son. Noel was a wild-born female chimpanzee that adopted the younger one, Thomas, after his mother died when he was young.

Shortly before the events in the study, Thomas died, apparently from a combination of a viral and bacterial lung infection. Most of the group went to visit Thomas's body, but most were lured away with attractive food – Noel, however, stayed by his side and cleaned his teeth with a grass tool, while her daughter looked on.

The behaviour is not of interest to scientists only because it is strange, though nothing like it has been observed before. It might also offer a look at the way that our thinking about death and our own mortality has emerged, they write in the study published in the journal Scientific Reports.

The researchers speculate that Noel may have stayed with her son's body because they seem to think that the dead body is not simply an inanimate object, but that it continues to be a "social being". It might also be that staying with the body helped learn about death, "perhaps fuelled by a curiosity about the unique circumstances", the researchers write.

That urge appears to be incredibly powerful. While Noel was cleaning her son's teeth, the caretakers tried to offer her food so that she would move away from the body and allow it to be removed from the enclosure – but she was so focused on the behaviour that she preferred to stay close to Thomas, rather than moving to eat the high-quality food.

Until now, behaviours like this were thought to be typically human, and limited only to ourselves. They represent the core and central part of human civilisation, even while they vary hugely across cultures.

But there is limited research on how much that behaviour is present in animals, and what it might mean for our understanding of death. The researchers ask that scientists focus to capture how animals behave in death-related situations and how they relate to the evolutionary origins of our own responses to death.