I bought this book because I had immensely enjoyed Matt Ridley's book on sexuality and evolution, The Red Queen. Whereas Ridley goes into excruciating detail about how certain evolutionary principles have affected a wide range of species, Shlain concentrates entirely on human evolution.
In the initial chapters, Shlain provides extensive explanations of the medical aspects of sex and childbirth. Shlain knows how to make these details interesting by highlighting their relevance. For example, he explains how the disproportionately large head of the human fetus endangered the lives of prehistoric women, and why the female tendency to lose iron was such a significant issue in ancient times. And these points are only the beginning. The first few chapters contain a dozen or so similar insights.
After Shlain provides the requisite background information, the book takes a more speculative turn. For the sake of argument, women are treated as a separate species, which Shlain calls gynosapiens. Because of certain evolutionary factors, gynosapiens were the first to become aware of time and mortality. In particular, sex was an act which carried potentially fatal implications for prehistoric women. Because the stakes were so high, gynosapiens took control of their own sexuality; they could not afford to be as carefree as men.
The subsequent evolution of male behavior (and society as a whole) is therefore explained in terms of male efforts to negotiate sexual relationships with women. According to Shlain, language itself evolved because the glibber male stood a better chance of succeeding with females. Most men (and women, I suspect) would agree that a significant portion of contemporary male behavior is motivated by sexual ambition. It is therefore not too much of a stretch to suggest that this motivation could have determined the evolution of human society at a fundamental level.
The author occasionally lapses into even more speculative arguments. For example, he proposes how color-blindedness, baldness, and homosexuality could have been useful characteristics in the early human gene pool. While these points are backed up by only minimal data, his arguments are reasonable. Furthermore, one must remember that any argument about prehistoric humans will necessarily rely on a fair amount of speculation.
Shlain has obviously spent a lifetime researching and reflecting on these issues. You may not agree with every one of his conclusions, but you are sure to finish this book with some valuable insights into human nature.
