When monkeys are born, the babies are often a totally different color from the parent, helping the monkey community to better identify and care for the offspring. Baby monkeys are virtually helpless, so in order to travel, one of the parents must carry the infant. When not travelling, baby monkeys spend their time playing. Marmoset and tamarin monkeys often have multiple births, producing twin or triplet babies.
Once a baby monkey reaches the age of about 6 months, its coloring changes to match that of its parents, and it is now considered a juvenile. The monkey's mother is almost always the parent who cares for the infant, including carrying the baby while travelling. Marmosets and tamarins are the exception, with the father caring for the infant and carrying it until it must be given to the mother for nursing. When baby monkeys play, it not only helps them to develop motor skills, they also learn valuable social and physical skills that are required to make them successful adult monkeys. A monkey is considered an adult between 18 months and 8 years old, depending on the particular species. A baby monkey can weigh anywhere from 0.5 to 31 ounces at birth.