In 1990, biologist Robert Dudley was enjoying a beer on a wide veranda overlooking a dense rainforest canopy. It had been a long, hot day on Barro Colorado Island, a six-square-mile landmass in the Panama Canal that’s become one of the world’s most researched rainforests thanks to the Smithsonian Tropical Research Institute there. Dudley was there to study insects, but that afternoon he was thinking about monkeys. As he sipped his beer and looked out at the spider monkeys plucking the ripe fruits of a hog plum tree (think delicious…
