Baby pygmy marmosets use vocalizations known as 'babbling' that are functionally similar to a human baby's babbling noises; these vocalizations help the baby pygmy marmoset practice using its vocal anatomy and also serve to attract attention from the animal's social group. Babbling is an acknowledged step in the process of language acquisition for certain animals, including humans and pygmy marmosets as well as songbirds and a specific species of bat, the sac-winged bat. Like human babies, these animals babble during their infancy as a means of replicating the sounds they hear coming from the adults around them.
The pygmy marmoset is a primate that starts making vocalizations at around 2 or 3 weeks old, and the vocalizations produced during this period can be relatively complex. Oftentimes, these babbles can include the repetition of a single sound before a new sound is produced, a process that is similar to the reduplicative babbling observed in human babies. If an adolescent pygmy marmoset spends time with a newborn of the same species, it may revert back to its babbling language, perhaps because the juvenile is once again seeking attention that is being paid mostly to the newborn. Babbling usage will eventually become more infrequent as the pygmy marmoset ages.