A baby orangutan wearing a diaper swings through the trees at the Sumatran Orangutan Conservation Program outside Medan, capital of Indonesia's North Sumatra province. The program takes mostly orphaned orangutans, nurses them back to health and releases them back into the wild. Anthony Kuhn/NPR hide caption

itoggle caption Anthony Kuhn/NPR

Tilda the orangutan, relaxing between gabfests at the Cologne Zoo. Cologne Zoo hide caption

itoggle caption Cologne Zoo