Previously, such behavior was believed to be unique to humans and chimpanzees.
When the dominant male marmoset (Callithrix jacchus) noticed the female lying on the forest floor, he immediately went to her, leaving behind two babies he had been caring for in the tree, and embraced her. He then sat with her for the next hour and 48 minutes. During this time, he prevented young individuals from approaching the dying female, behavior previously observed in chimpanzees.
The male marmoset sat with his dying mate and prevented young individuals from approaching. Credit: University of Bristol.
The long-term relationship between the dominant pair (which lasted at least three and a half years) and their social status in the group may have contributed to the male’s behavioral response, the scientists said.
Citation: Bruna Martins Bezerra, Matthew Philip Keasey, Nicola Schiel, Antonio da Silva Souto, 'Responses towards a dying adult group member in a wild New World monkey', Primates
April 2014, Volume 55, Issue 2, pp 185-188 DOI: 10.1007/s10329-014-0412-8