At some point between 195,000 and 123,000 years ago, the population size of Homo sapiens plummeted, thanks to cold, dry climate conditions that left much of our ancestors' African homeland uninhabitable. Everyone alive today is descended from a group of people from a single region who survived this catastrophe... ...studies of the DNA of modern-day people indicate that, once upon a time, our ancestors did in fact undergo a dramatic population decline. Although scientists lack a precise timeline for the origin and near extinction of our species, we can surmise from the fossil record that our forebears arose throughout Africa...