This book is a fascinating collection of just about everything one could imagine about male and female differences. Every women and gender studies academic program on the planet should have a copy of this book in their department's library. Every faculty member, who teaches anything that is related to sex and gender, should spend an evening flipping through this book. Every student with similar interests should also spend some hours with this volume, just to get a sense of how much is already known. If they are exploring research projects, this book will help them decide what is and is not worth studying. No encyclopedia of this sort could ever be perfect. Thus it is not surprising that I could find a few minor errors and omissions. For example, in one small table that digresses off of humans, and there is a reference to a study on a lizard, which is called an amphibian even though it's a reptile. Some well-documented sex differences in osteology are not included. But that sort of specific information can easily be tracked down in physical anthropology and forensics texts. If you are in the fields of gender studies, women's studies, sexology, sociology, psychology etc., make sure that your university or town library orders a copy of this book.