In this book, the author tries to make a case to put our notion of morality onto the scientific landscape with clear cut do's, don'ts and their relevant explanation, as opposed to something that may be different for each of us and each culture. Naturally, in doing so he has to heavily criticize many different common practices from all around the world, most notably female circumcision and suppression, among many others.
He makes a very strong case that you can judge the morality of your actions by the well-being of the affected people, and that you can map right and wrong decisions in your brain, which is why psychopaths will be unable to alter their behaviour (they lack the ability to see the wrong in their actions).
All in all this book is very, very interesting, but especially in the beginning I found it very difficult to get into this book and follow his train of thoughts. It probably helps if you can lock yourself into a remote cabin over a long, rainy weekend...