Baby marmosets may practice their first distinctive cries in the womb

Ultrasounds tracking fetal mouth movements pinpoint when vocalization motor skills develop

Marmoset carrying two babies on its back

Baby marmoset monkeys, like the ones shown here, are born knowing how to cry. Ultrasound videos suggest they start practicing the motions in utero.

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Cradled inside the hushed world of the womb, fetuses might be preparing to come out howling.

In the same way newborn humans can cry as soon as they’re born, common marmoset monkeys (Callithrix jacchus) produce contact calls to seek attention from their caregivers.