In the wild, mountain gorillas live an average lifespan of 35 years, though some gorillas may live as long as 50. In captivity, with the proper environment, gorillas can live just as long as the do in the wild.
After gorillas are born, they cling to their mother's fur until they are about four months old. At that point, they have acquired the skill to ride on her back. Young gorillas stay with their mothers until they reach the age of two or three. At that point, they are done nursing and are able to be much more independent. Adulthood comes a few years later when they can fend entirely for themselves.