Ponso, the sole survivor of a colony of 20 chimpanzees, sits in a tree on Chimpanzee Island near the town of Grand Lahou, Ivory Coast. Only Ponso remains of a group of chimpanzees relocated to the island from Liberia in 1983 by a research laboratory for medical tests. An effort is under way to keep Ponso alive and well in Ivory Coast where the ape population has plummeted by 90% in two decades.

Photograph: Issouf Sanogo/AFP/Getty Images