Hand by William Bookwalter. "One of the things that dissolves the barriers between man and other apes are the hands the help us move through the world. This is the hand of Ivan the gorilla, an infant we had to hand-raise and reintroduce to his troop in Pittsburgh in 2013. The private moments between a keeper and an unlikely companion are what compel us to continue the fight against extinction." To see more of William's photographs please go to https://members.nationalgeographic.com/160874679356/