A Brief History of Everyone Who Ever Lived: The Human Story Retold Through Our Genes

We can learn a lot about history by looking at DNA sequences. Advances in technology make it much easier to sequence DNA that we can find in long-dead remains.  Other "human-like" species have existed and mated with humans, yet they no longer exist today. However, there are still traces of their genetic materials. Europeans and Asians have some Neanderthal genetic material, yet Africans seem to lack it. We can even analyze the distribution to determine which side tended to be females and male in the early mating. 

This book is a discussion about what our genes can and cannot tell us. A lot of what we can know involves comparing DNA to known sources. What we have trouble knowing is the impact certain genes have on individuals. The news will often report that scientists have discovered a gene for a certain trait. However, this simply indicates there is a statistical relationship between the gene and trait. It may be fairly useless. A large percentage of incarcerated people may have a gene. Yet, if the gene is also prevalent in a large percentage of free people, it doesn't tell us much. Genes will often work together with other genes making it unlikely a single gene will indicate much. We can consider this the start of scientific research rather than the end.