Monogamy is traditional in most cultures, and it is the law throughout America since Utah gave up polygamy to acquire statehood. Is there any philosophical basis for favoring monogamy over polygamy? Or any reasons grounded in clear empirical facts or social needs? With a looming shortage of females relative to males in large parts of Asia, is it time to question this traditional assumption about marriage? John and Ken remain faithful to their guest, renowned anthropologist Helen Fisher, author of Why We Love: The Nature and Chemistry of Romantic Love.