Reproduction and raising of the youth
The orangutan infant is constantly being carried by its mother for about a year and only after that time will be weaned. Only after the first year does it start moving away from its mother and feeding on solid food. Even after the first year it continues to be breast-fed and carried over long distances, until its mother gives birth again.
Even then the child will still stay with its mother and only leave her at about nine years of age. By that time an orangutan has learned enough (about climbing, nest building, feeding, orientation, etc) to survive on its own. Around the age of 12 a female will give birth for the first time.