This is probably the most heretical work I have ever or will ever put to writing personally, and probably one of the most heretical things from the perspective of progressives, feminists and any other member of the cathedral available anywhere. If you want a no-nonsense (i.e., no feminism) description of sex differences, then you will probably enjoy the information contained within. If you have questions about what exactly the gender differences in intelligence are, by what fairly exact biological mechanisms they come about, and what potential evolutionary narratives explain what we observe, then this is the book for you. After reading this book you will not only know the current patterns of sex differences in intelligence as shown by psychometric tests, but why and how the underlying biology explains the patterns we observe. At the heart of the differences is both genetic and hormonal elements which work in concert to generate what we see on an every day basis. It has taken years of work (since 2011) and hundreds of hours invested in reading hundreds of dry academic papers to compile the more than 300 sources included, but I did so you can have the evidence all in one place and explained in lay terms. And perhaps most importantly, to have the evidence for gender differences in intelligence without muddying the waters with the foul taint of feminism.