For the first time, chimpanzees have been observed using tools to clean the corpse of a deceased group member, scientists say.
Researchers, including those from University of St Andrews in the UK, observed a female chimpanzee sitting down near the dead body of a young male, selecting a firm stem of grass, and intently removing debris from his teeth.
They suggest that the isolated activities of the chimp in the video might offer some clues as to how mortuary rituals began in humans.
Chimps have been observed cleaning one another's teeth on multiple occasions. Besides serving as a hygienic practice, it is believed to be a bonding ritual as it typically occurs between those that are seen to be close to one another.
However, never before has a chimp been observed tending to the teeth of a deceased member of their group.
The chimps involved were living in the wild at Chimfunshi Wildlife Orphanage Trust in Zambia and the deceased young male chimp appeared to have died due to a lung infection.
The deceased chimp had been orphaned four years before and was subsequently adopted by the older female, 'Phys.Org' reported.
Prior to the teeth cleaning, the older chimp had cradled her adopted son's head in her hands as she examined his teeth.
It is impossible to know the motives of the older chimp, though it is easy to apply human emotions to the scene shown in the video - it looks like a grieving mother, researchers said.
The research was published in the journal Scientific Reports.