Scientists from the Hebrew University of Jerusalem have recorded spontaneous ‘phee-call’ dialogues between pairs of marmoset monkeys. They’ve found that marmosets use these calls to vocally label each other; moreover, these non-human primates respond more consistently and correctly to calls that are specifically directed at them.
Humans, dolphins, elephants, and marmoset monkeys are the only known species that vocally label their conspecifics. Image credit: Oren et al., doi: 10.1126/science.adp3757.
In the study, Hebrew University of Jerusalem graduate student Guy Oren and colleagues recorded natural conversations between pairs of marmosets, as well as interactions between monkeys and a computer system.
The researchers found that these monkeys use their phee-calls to address specific individuals.
Even more interestingly, the marmosets could discern when a call was directed at them and responded more accurately when it was.
“This discovery highlights the complexity of social communication among marmosets,” Omer said.
“These calls are not just used for self-localization, as previously thought — marmosets use these specific calls to label and address specific individuals.”
The authors also found that family members within a marmoset group use similar vocal labels to address different individuals and employ similar sound features to code different names, resembling the use if names and dialects in humans.
This learning appears to occur even among adult marmosets who are not related by blood, suggesting that they learn both vocal labels and dialect from other members of their family group.
The scientists believe that this vocal labeling may have evolved to help marmosets stay connected in their dense rainforest habitat, where visibility is often limited.
By using these calls, the primates can maintain their social bonds and keep the group cohesive.
“Marmosets live in small monogamous family groups and take care of their young together, much like humans do,” Omer said.
“These similarities suggest that they faced comparable evolutionary social challenges to our early pre-linguistic ancestors, which might have led them to develop similar communicating methods.”
The research provides new insights into how social communication and human language might have evolved.
“Our findings shed light on the complexities of social vocalizations among non-human primates and suggest that marmoset vocalizations may provide a model for understanding aspects of human language, thereby offering new insights into the evolution of social communication,” the researchers said.
The findings appear in the journal Science.
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Guy Oren et al. 2024. Vocal labeling of others by nonhuman primates. Science 385 (6712): 996-1003; doi: 10.1126/science.adp3757