New twins continue to arrive twice a year, so an extended family group might have from 4 to 14 individuals, but only one female breeding at a time. The Best Father Award may go to marmosets and tamarins. These fathers are highly devoted to their babies. Although juveniles and non-breeding females may also help out, the fathers do most of the work. To share the tasks of looking out for predators, looking after infants and foraging.
Adults often share food with babies, juveniles and sometimes even adult children.
The experience also gives juveniles good practice to become better parents when they grow up. Juveniles removed too early from their social group later make poor parents. Their main defence is vigilance and speed, although they may mob smaller or slower predators. A new marmoset was discovered in 1994. The Satarei Indians believe marmosets and tamarins are reincarnations of their dead children and commonly tame these creatures.