Developmental Trajectories in Infant Marmoset Vocalization Rates

Abstract

Common marmosets are a model species used to study the evolution and development of vocal communication. This study examined recordings of their vocalizations when in social isolation to assess the developmental trajectory. Measures included changes in overall call rate, changes in proportion of different call types, differences by relatedness, and differences by sex. The vocalizations of ten infant marmosets were recorded when alone for about 5 minutes from birth to 2 months when separated from their family groups. The marmosets started out producing numerous calls of a variety of call types, but converged on one call type and fewer calls by about 6 weeks. There were no differences by relatedness, but females developed faster than males. This study found that marmosets begin to produce adult-like calls appropriate to their situations by 6-7 weeks of age. It also establishes a baseline for future studies on marmoset vocal development.