Marmoset monkeys learn to call the same way human infants learn to babble. Human social groups have a strange tendency to share responsibility for taking care of infants; parents, older siblings, and other adult relatives all help to nurture babies. The only other primates that take care of infants this way are marmosets, a group of small, highly social monkeys from South America. In another striking parallel to humans, infant marmosets also benefit from frequent feedback while learning their vocal calls. Ref. Source 8j.