Some 45,000 years ago, the tropical rainforests of Sri Lanka teemed with dangerous plants and lacked big game, yet people made a life there. Our key to success in that seemingly inhospitable region? It was monkeys and squirrels, researchers say — or rather, our ability to catch them.

“These animals are difficult to catch and suggest a certain level of sophistication in terms of hunting strategies,” said Patrick Roberts, an archaeologist at the Max Planck Institute for the Science of Human