A new study found that marmoset monkeys also engage in polite conversations very similar to how humans communicate with each other.
Researchers Asif Ghazanfar and Daniel Takahashi from Princeton University observed how the marmoset monkeys communicate with each other. They saw that they carry a friendly demeanor and converse using vocal sounds. They can also communicate even without seeing each other.
"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 Ghazanfar in a press release.
Although they don’t use the human syntax and complex language, the primates do exude a cooperative upbringing and communication.
"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," said Ghazanfar.
To verify their hypothesis, the marmosets were separated by curtains inside a room. This allowed the monkeys to hear calls without seeing each other. Out of the 10 marmosets arranged in various combinations, about 54 records were documented for their analysis.
The scientists carefully studied the monkey’s phee calls, the vocal sounds they make when trying to contact another through long distance or in this case without seeing each other. They discovered that conversations between the marmosets do not overlap. In other words, the monkeys do not have the bad manners to interrupt another marmoset while talking. Instead, they wait for the other to finish before they reply.
The study found that “The consistent waiting period of about 5-6 seconds upon hearing a call establishes a turn-taking rule.”
The waiting time in between marmoset conversations is not the same for humans which are hundreds of milliseconds. The difference can be explained by the applicable “unit of perception” used by the marmosets and humans. The smallest unit for us humans is a syllable or a word while the marmosets perceive a complete phee call as their shortest.
Further studies on the marmoset monkeys are being undertaken specifically during pregnancy and the first few years of the newborns. Scientists will try to find out what causes speech disorders by analyzing the vocal sound exchange between mother and baby marmosets.
The study was published in the Oct. 17 issue of the Current Biology.
