In a groundbreaking study, researchers from David Omer’s lab have discovered that marmoset monkeys engage in “naming” behavior to identify each other, a trait previously documented only in humans, dolphins, and elephants. This remarkable finding sheds light on the complexity of social communication in marmosets and may offer new insights into the evolutionary roots of human language.
The researchers use machine learning tools to analyze hundreds of spontaneous vocal exchanges between marmoset pairs, and found that the primates use vocal labels to identify their peers. This behavior is similar to how humans use names. The study further revealed that marmosets respond accurately to calls specifically directed at them, suggesting a clear understanding and use of these “names.” Beyond this individual labeling, the study also found that marmosets from the same family use similar “names” to label other monkeys. This indicates that ”names” in marmoset groups are likely learned within family circles, as they extend even to adult family members which are genetically unrelated.
These findings redefine our understanding of primate vocalization, which was once considered rigid and unrelated to human language development. This finding of clear naming behavior in marmosets challenges long standing assumptions about primate communication and underscores the sophisticated nature of marmoset social interactions. This discovery opens new avenues in the study of language evolution, highlighting marmosets as a unique model for exploring the roots of vocal communication.

Figure caption:  A) The colored distributions represent the accuracies of our classifier models  in predicting each receiver’s identity based on Adonis’s calls. In contrast, the gray distributions show the accuracies when receiver identities are shuffled, serving as a control. The red line indicates the expected chance level for detecting the correct receiver identity among four possible labels. B) Example calls, one for each of Adonis’s receivers, demonstrate clear differences in vocalizations directed toward different individuals.