Baby marmosets learn to make their calls by trying to repeat their parents’ vocalizations, scientists report today in Current Biology. Humans were thought to be the only primate with vocal learning—the ability to hear a sound and repeat it, considered essential for speech. When our infants babble, they make apparently random sounds, which adults respond to with words or other sounds; the more this happens, the faster the baby learns to talk.
To find out whether marmosets (Callithrix jacchus, pictured) do something similar, scientists played recordings of parental calls during a daily 30-minute session to three sets of newborn marmoset twins until they were 2 months old (roughly equivalent to a 2-year-old human). Baby marmosets make noisy guttural cries; adults respond with soft “phee” contact calls (listen to their calls below).
The baby that consistently heard its parents respond to its cries learned to make the adult “phee” sound much faster than did its twin, the team found. It’s not yet known if this ability is limited to the marmosets; if so, the difference may be due to the highly social lives of these animals, where, like us, multiple relatives help care for babies.