This is a very good popscience book. It explains in a simple way some of the methods that can be used to study and uncover the genetic as well as linguistic and cultural past of the human species. (Interestingly, it turns out that some of the methods for studying genetic change are similar to some of the methods for studying cultural and linguistic change, and that the history of genes can help us understand the history of languages and vice versa.) But the book does not just explain the methods, it also tells you what results these methods have yielded. That is, it tells you when (probably) modern humans came out of Africa, the way they colonised the whole planet, the way linguistic differentiation took place, etc. The book is well written and entertaining.