In his book, The Journey of Man: A Genetic Odyssey, Wells describes the exodus from Africa that began around 60,000 years ago, and the path we took to populate the world.

Following the southern coastline of Asia, the first early travelers crossed about 250 kilometers [155 miles] of sea, and colonized Australia by around 50,000 years ago. The Aborigines of Australia, Wells says, are the descendants of the first wave of migration out of Africa.

A second wave left Africa around 45,000 years ago and settled in the Middle East, with smaller groups going off to India, northern China, and southern China. As the glaciers of the Ice Age began to retreat around 40,000 years ago and temperatures warmed up, humans moved into Central Asia and multiplied quickly.