Around 200,000 years ago, a man--identical to us in all important respects--lived in Africa. Every person alive today is descended from him. How did this real-life Adam wind up father of us all? What happened to the descendants of other men who lived at the same time? And why, if modern humans share a single prehistoric ancestor, do we come in so many sizes, shapes, and races?

Showing how the secrets about our ancestors are hidden in our genetic code, Spencer Wells reveals how developments in the cutting-edge science of population genetics have made it possible to create a...