 Koko was the 50th gorilla born in captivity and one of the first gorillas accepted by her mother in captivity.Koko remained with her mother until the age of one when she was taken to the zoo's hospital to be treated for a life-threatening illness.Patterson along with Charles Pasternak originally cared for Koko at the San Francisco Zoo as part of their doctoral research at Stanford University after Koko came to the zoo's hospital.