An amazing book that covers all angles on human nature without telling you in what you should believe but giving you a choice to make up your mind yourself.
This book gives an excellent overview on the evolution of separate sexes, combining the best out of different theories into a rather convincing one; it does leave many possibilities open, and rightly so, wherever the evidence isn't enough. The examples span from viruses to the most complex mammals, and in that regard is quite satisfying.
The second half focuses on human beings. The good part is that it does so in an anti-politically correct manner, defying much prejudice such as the female and male brain being identical, while still being fair to either sex (while either sex is not fair with the other, if you're familiar with genetic arms races).
The bad part is that it does so with too much emphasis on the genetic component. While it is true that such component has long been ignored by anthropologists, sociologists and some psychologists, it does the opposite error. The environment (both natural and artificial), memetics or culture are never taken into consideration, with the result that sometimes conclusions are quite heavy handed and not supported by any non-speculative evidence.
A shame, for the book is an encomiable one in style, scope and aim.