by Marmosets can communicate with each other by name and know when they are being addressed, joining a very short list of species that exhibit such behavior, and the first by a non-human primate, to have been discovered at a new study.
The monkeys use distinct calls, called “fee-calls,” to call each other, which scientists say is a “highly cognitive” behavioral pattern that has only been observed in humans, dolphins and elephants.
The discovery, made by a team from the Hebrew University, is described in a study published Thursday in the journal Science.
“This is the first time we’ve seen this in a nonhuman primate,” David Omer, lead author and assistant professor at the university’s Safra Center for Brain Sciences (ELSC) told CNN on Thursday.
The tree-dwelling primates are very social animals and live in small groups in South America but the researchers collected data at a university animal facility in Israel.
“The experiment was very simple,” Omer told CNN. “We have placed two marmosets in the same room and placed a visual barrier between them.
“When you do this they spontaneously start to engage in dialogue.”
Omer’s team recorded natural conversations between pairs of marmosets, as well as interactions with a computer system, which led to the conclusion that the marmosets addressed specific individuals with the “pee calls”. In addition, the animals were able to recognize when they were being called and respond more accurately in these situations.
Ten marmosets from three different family groups were recorded communicating during the process, highlighting “the complexity of social communication among marmosets,” Omer said in a press release.
He told CNN: “Until now, we thought that nonhuman primate vocalization was a genetically fixed and inflexible form of communication. But we now see that marmosets are capable of producing a very flexible vocabulary.”
According to the study, marmosets rely heavily on vision but also exhibit a “complex range of social calls” – one of which is the “pee call”. The calls are generally used to communicate when they are out of sight of each other.
In addition to using different calls for different individuals, marmosets were also found to be able to distinguish between directed and non-directed calls.
They were previously interpreted as a means of “self-localization,” according to Omer—in other words, a way to communicate one’s position to others. But the new study showed that the sounds were used as “specific calls to label and address specific people.”
The investigation also showed that marmosets from the same family group used “similar vocal labels to address different people” and used “similar sound features to code different names,” the release says. This practice, according to the study, is similar to the use of names and dialects in humans.
Interestingly, the learning pattern could also be seen with adult marmosets who are not blood relatives, suggesting that they learn vocal labels and dialects from other members of the same group.
Omer told CNN: “We can definitely say that there was a learning process happening here – so they learn the names of family members – and it’s not genetic.”
Omer and his colleagues believe their research provides new insights into how human language and social communication may have evolved.
He told CNN: “Until now we thought that human language was a big bang phenomenon that happened out of nowhere and only in humans – which is completely contrary to evolutionary theory.
“This finding, along with other findings, suggests for the first time that there were precursors to the development of language in non-human primates and we can find evidence of an evolutionary process.”
Earlier this year, another study found that African elephants can address each other using individual calls that are similar to the personal names used by humans.
That study’s lead author, Mickey Pardo, an animal behaviorist and postdoctoral fellow at Cornell University in New York, told CNN that the marmoset paper was “a very thorough piece of experimental work,” which “challenges the established but date that people. the only primate that can learn voice.”
However, Pardo expressed concern about the idea that “different marmosets use the same name for the same receptor.” He said his team reached a similar conclusion in their elephant study before doing further research that undermined their findings.
He said: “The more species we can find that have names or something similar, the more opportunity we have to use the comparative method to learn about the selection pressures that might be reason for the evolution of names in our own species.”
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