Gender conflict is reflected in religious dogma—from the commandment to marry your neighbor to the establishment of mutual sexual obligations between spouses. Codes of law created under its influence dictate who can and cannot have sex with whom. Its manifestations shape our sexual morality, defining what should elicit our enthusiastic approval and what should elicit scornful condemnation. The double standards it generates are widespread even in the most sexually egalitarian cultures on the planet. But while we all face sexual conflict, most of us see only the tip of the iceberg: cheating on a date, the unseemly exploits of a politician, the slow disintegration of a once-happy marriage, the brutal breakup of a romantic relationship. Why Men Do It shows that the war between the sexes is something far deeper and more global than we think. David Buss reveals the mechanisms of this phenomenon, which have developed over the course of long-term evolutionary changes in our sexual psychology, formulates a new unified theory of sexual conflicts, and simultaneously offers practical advice to men and women who would prefer to avoid these conflicts.