Introduction

This introduction presents an overview of the key concepts discussed in the subsequent chapters of this book. The book describes a shorter story about how sex, one of evolution’s oldest and greatest innovations, plays out in human social life. It also describes human social life as a play of biology that echoes in culture. The book focuses on two evolutionary principles, visible throughout the cosmos. One is growth through differentiation of form. A second evolutionary principle, related to the first, is involution of the whole in parts. Sex produces and reinforces social life, which redounds to produce and reinforce sex. The book shows that the unity of species explains how species develop and profit from biological and cultural divisions. Species divisions and dynamics manifest and maintain an abiding unity. The sexes are big limbs that divide the trunk of the species and that must balance to maintain the working integrity of the species.