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

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.

• 儿童和青少年： 15-19岁青少年癌症发病率持续上升，14岁及以下儿童的发病率有所下降。1970年以来，儿童癌症死亡率下降了70%，青少年死亡率下降了63%，很大程度上因为白血病治疗手段进步。