Marmosets share a unique characteristic with humans: In conversations, these social monkeys wait their turn to speak.
During exchanges, which can last up to 30 minutes, marmosets engage in vocal turn-taking and they don’t interrupt each other, researchers from Princeton University report in Current Biology.
“We were surprised by how reliably the marmoset monkeys exchanged their vocalizations in a cooperative manner, particularly since in most cases they were doing so with individuals that they were not pair-bonded with,” said Asif Ghazanfar, one of the study’s authors, in a news release. “This makes what we found much more similar to human conversations and very different from the coordinated calling of animals such as birds, frogs, or crickets, which is linked to mating or territorial defense.”
Talk to Me
Ghazanfar and his colleagues looked at marmosets because of what they have in common with humans—they are extremely social and talkative primates.
In the study, they placed marmosets in opposite corners of a room and then separated them with barriers. The barriers blocked their sight, but not the sounds, of the other monkeys. In this situation, the marmosets made a specific kind of contact call known as a “phee” call.
Marmosets took turns calling, waiting about 5 seconds after their partner was finished to respond. And if one marmoset slowed down or sped up the rate of its calls, its partner tended to do so, as well.
These results suggest marmosets, like humans, follow simple rules in their conversations.
For marmosets, there are several advantages to being polite conversationalists. If a monkey is separated from its social group, exchanging contact calls brings comfort. And taking turns calling could let your conversation partner know that you are listening.
In their contact calls, marmosets also convey information about their gender, identity, and social group. Vocal turn-taking could allow marmosets to fully extract all this information, especially in noisy forest environments.
The researchers say marmoset vocal turn-taking may represent a basic foundation upon which more sophisticated forms of communication arose in humans.
Eavesdropping on the conversations of this tiny, talky monkey could shed light on the roots of human communication — and maybe inspire us to be more polite conversation partners.