In 1996, a 3-year-old boy fell into a gorilla enclosure, sustaining a broken hand and a deep facial cut from the 20-foot fall. Seven gorillas were inside, but one, Binti Jua, cradled the boy while her own infant rode on her back.
She carried him to the edge and waited for zookeepers to safely retrieve him.
The boy spent four days in hospital, and Binti received worldwide praise and special treats.
Experts say her maternal instincts, reinforced by her own baby, guided her protective behavior.