Modern life makes us tired, right? But research from societies in Africa and South America suggests people in the ancient world slept only 6.5 hours a night.

Modern life makes us tired, right? But research from societies in Africa and South America suggests people in the ancient ...

巨型水獭。作者：Bernard DUPONT，来自法国 - 巨型水獭（Pteronura brasiliensis）正在吃一些鱼……，CC BY-SA 2.0，https://commons.wikimedia ...

哥斯达黎加托尔图杰罗国家公园。作者：加利福尼亚州埃尔索布兰特的 Becky Matsubara - 绿红翠鸟（雌性），CC BY 2.0，https://commons ...