Are dialects socially learned in marmoset monkeys? Evidence from translocation experiments

Area of Science:

• Animal Behavior
• Bioacoustics
• Primate Communication

Background:

• Vocalizations in common marmosets exhibit population-specific differences, potentially due to vocal learning, environmental, or genetic factors.
• Distinguishing the drivers of these vocal dialects is crucial for understanding primate communication evolution.

Purpose of the Study:

• To investigate the influence of physical and social environments on common marmoset vocalization acoustics.
• To differentiate between genetic, environmental, and social learning as causes for population-specific vocal dialects.

Main Methods:

• Conducted translocation experiments with common marmosets to isolate environmental and social influences on vocalizations.
• Experiment 1: Translocated marmosets to a new physical environment; assessed vocal changes over 5-6 weeks.
• Experiment 2: Translocated marmosets to a new population with a distinct dialect; assessed vocal convergence over 16 weeks.

Main Results:

• A novel physical environment did not induce lasting changes in marmoset vocalizations.
• Translocated marmosets showed vocal convergence towards the new population's dialect, even without direct social interaction.
• This suggests acoustic input alone can drive vocal modifications in common marmosets.

Conclusions:

• Common marmosets exhibit crowd vocal learning, modifying calls based on acoustic exposure to conspecifics.
• This study provides the first evidence of crowd vocal learning in a primate species and distinguishes drivers of vocal dialects.