The incident was captured by Dr Bruna Bezerra and colleagues in the Atlantic Forest in the Northeast of Brazil.  Dr Bezerra is a Research Associate at the University of Bristol and a Professor at the Federal University of Pernambuco in Brazil.

It is the first time that compassionate care-taking behaviour towards a dying adult group member has been observed in monkeys.  Previously, such behaviour 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, behaviour previously observed in chimpanzees.

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 behavioural response, the scientists said. 

Paper

'Responses towards a dying adult group member in a wild New World monkey' by Bruna Martins Bezerra, Matthew Philip Keasey, Nicola Schiel, Antonio da Silva Souto in Primates