Like humans, marmosets – tiny monkeys with ear tufts similar to Einstein’s native to Brazil – overhear conversations between others, and prefer to talk to individuals they see positively, study in the iris Advances in science showed Wednesday.
While behavioral research has built knowledge around the social lives of prime ministers, it has been likely that there were no reliable ways to validate an “inner vision,” a person or an inner workings of the mind.
Marmosets are a great species to study because of their close social structure: They live in fully cooperative groups of about 15 family members, with the entire extended clan responsible for raising children. .
How do they decide who is trustworthy and who is not?
A team led by Rahel Brugger at the University of Zurich (UZH) took recordings from 21 adult marmosets captured by a secret speaker of an adult of the opposite sex making either food tender calls or aggressive chat calls in response for begging babies.
As a control, they also played the marmosets calls made by one individual.
The scientists then identified infrared cameras at the faces of the marmosets to record the nasal temperature – looking for droplets that show the monkeys were alert and engaged.
The tests found that the marmosets responded to only unified calls and not individual calls, indicating that they understood when real conversations were taking place.
After playing the records, the team allowed the marmosets into a room full of toys and mirrors.
Marmosets do not recognize the shadow itself, so they believed it represented the monkey that made the recorded call.
The researchers found that, in general, the marmosets preferred to go near when the records showed that the person was helpful.
“This study adds to the growing evidence that many animals are not only passive observers of third-party interactions, but are also interpreted,” he said. the paper’s lead author and professor of anthropology at UZH, Judith Burkart.
The team plans to use this temperature mapping method for future studies, such as about the origin of morality.
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