Preface

The first scientist to raise scientific questions about sex differences was Charles Robert Darwin, as part of his research into differences among members of the same species. Since Darwin's research, many scientists have studied sex differences and concluded that there are two different states for females and males. One is the sex difference, which is biological and congenital, based on genes and completed by hormones. The other difference is gender, which is social, cultural, acquired, not based on genes, but rather shaped by environmental factors. Scientists have argued whether the differences between females and males are innate or occur after birth, when differences are influenced by the environment, that is to say - "Nature or Nurture". For example, Sigmund Freud made the famous remark "Anatomy is destiny", whereas Simone de Beauvoir claimed that "One is not born a woman, but becomes one." I do not believe that females and males are shaped solely by nature or nurture; rather, I believe that they are formed out of the interaction between nature and nurture. Therefore, this book offers new ideas not only to life scientists and biologists, but also to social and cultural scientists.

It has become clear in recent years that sex differences and similarities in biology have influenced physiological and pathological functions. However, there have been few reports on intentional studies of sex differences, and many reports have been published as by-products of other kinds of research. Sex difference specialists in their own respective fields contributed to this book. They have chosen not only humans as the subjects of their studies, but other mammals, birds, amphibians, insects, and extended the scope to ostracoda in the Paleozoic era. Moreover, they have used original methods in individual studies. My own contribution offers somewhat different data on sex differences to readers.

Nowadays, studies in life science are not complete without factoring in sex differences. Researchers have been exploring new medical treatments under the assumption that physical characteristics in females are different from those in males. I hope that this book will be able to contribute to the advancement of life science and the progress of gender-specific medicine.

I offer my thanks to the production team at InTech, under the leadership of Oliver Kurelic and Natalia Reinic, for their guidance, professionalism and unfailing support.

#### XII Preface

In what has truly been a team effort, it is difficult to single out individuals for special mention.

I am also grateful to Ikuko Moriyama, librarian and my long-suffering wife, for assistance in preparing the manuscript, and her patience and tolerance throughout the last two years.

> **Hiroshi Moriyama** Showa University School of Medicine Japan
