For hundreds of thousands of years, one rule has governed humanity in times of crisis: Women and children first.

This book reveals the cold biological truth behind that instinct. One man can father thousands of children. One woman can only produce a limited number in her lifetime. That single fact made women the more valuable sex for the survival of the species.

From the decks of the Titanic to the battlefields of history, from the male sex drive to the quiet sacrifice of men in war, this book follows the logic without apology. It explains why societies protect women first, why men were given such a powerful urge, and why the tension between the sexes runs so deep.

Once you understand the hidden mathematics of human reproduction, you will never look at men, women, sex, or sacrifice the same way again.