Some orphaned chimpanzees, bearing the loss of their mothers due to an epidemic,
illness, or bushmeat hunting, may be looked after and protected by an older sister or another female. Orphans who
survive are often small for their age due to the lack of mother's milk. Other foods nourish their bodies sufficiently
to keep them alive but they need to continue nursing until age five or six to grow strong bones and bodies.
Jane's observation:
From that moment Miff, to all intents and purposes, adopted her little brother. She waited for him when she went from place to place; she allowed him to share her nest at night; she groomed him as frequently as his mother would have done. For the first few days after his return she even permitted him to ride occasionally on her back; but after that she pushed him off if he tried to jump on-she was a thin, long-legged youngster and Merlin was probably too heavy for her. It seemed that Pepe was with his younger siblings more than when Marina had been alive; possibly because Miff, deprived of a mother, followed him instead. And when he was there, Pepe normally went to Merlin's assistance during moments of social excitement.
