Have you come across someone who seems to be eavesdropping on a conversation? Well, certain monkeys do something similar. But its end is not just gossip, but a deeper one. Marmoset monkeys distinguish conversations from others and spy attentively. They observe interactions between third parties in order to decide who to interact with. It has been accredited by a team of anthropologists from the University of Zurich.
They measured the changes in temperature on the marmosets’ faces by quantifying subtle emotional responses. “You don’t perceive vocal interactions between congeners as the mere sum of the elements of a single call. But as holistic as a conversation, “says first author Rahel Brügger.
They used reproductions of the voice exchange between marmosets. And also calls from individual animals that did not take part in an interaction. “This showed that the response to call interactions was significantly different than the response to individual calls,” said Brugger. “Marmoset monkeys can thus distinguish a dialogue between their peers from a pure monologue.”
Friendly and cooperative
The researchers observed something else. Marmoset monkeys distinguish conversations from others in order to find out who to engage with: they choose those who have worked cooperatively with third parties. This preference corresponds to the social system and natural behavior of these small Brazilian monkeys. They are cooperative breeders and rely on the cooperation of the members of their group.
“Many animals are not just passive observers of interactions with others. But they also interpret them, “concludes the youngest author Judith Burkart in a statement.” Thermography can show how non-verbal subjects perceive these social interactions. “