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The paradox of polygamy II: Why most women benefit from polygamy and most men benefit from monogamy

Would you be the third wife of Matt Damon?

Contrary to popular belief, most women benefit from polygynous society, and most men benefit from monogamous society. This is because polygynous society allows some women to share a resourceful man of high status. George Bernard Shaw (who was one of the founders of the London School of Economics and Political Science where I teach) put it best, when he observed, “The maternal instinct leads a woman to prefer a tenth share in a first rate man to the exclusive possession of a third rate one.”

Or, as the comedian Bill Maher asked his panel on his TV show Politically Incorrect on January 7, 1998, “Would you rather be the second or third wife of Mel Gibson or the only wife of Willard Scott?”, to which one of the panelists, the conservative commentator and activist Susan Carpenter McMillan, responded, “If it comes to Mel Gibson, I wouldn’t care if I was one, two, or three.” Of course, this was back when Mel Gibson was highly desirable. Substitute Matt Damon for Mel Gibson. The cast of characters changes in a decade, but the principle remains the same.

In contrast, most men benefit from monogamous society. Given a 50-50 sex ratio, monogamous society virtually guarantees a wife for every man, even a third-rate one. Under polygyny, some third-rate men may not find a wife at all, or, even if they are lucky enough to find one, their wife will not be as desirable as the one they can secure for themselves under monogamy, because under polygyny more desirable women would have become the second, third, or tenth wife of more desirable men.

The exceptions to this rule are highly desirable women, who benefit from monogamous society, and highly desirable men, who benefit from polygynous society. A highly desirable woman can marry a highly desirable man under any circumstances, but under polygyny she’d have to share her desirable husband with other women, whereas under monogamy she can monopolize him. A highly desirable man can acquire multiple wives under polygyny, but must confine himself to only one wife (albeit a highly desirable one) under monogamy.

It’s the nature of the statistical (“bell curve”) distribution, however, that most people are not extreme on either side; for example, most people are not extremely tall or extremely short, but of more or less average height. Similarly, most men and women are neither extremely desirable nor extremely undesirable. So most men benefit under monogamy, and most women benefit under polygyny.

When men imagine what living in a polygynous society might be like, they imagine themselves married to several wives. What they don’t realize, however, is that, more than likely, they would be left without any wife in a polygynous society. Polygynous marriage in a polygynous society is always limited to a minority of men. If 50% of men have two wives each, then the other 50% cannot have any wives. If 25% of men have four wives each, then the other 75% cannot have any wives. When women imagine what living in a polygynous society might be like, they imagine themselves having to share their current, no-good loser of a husband with other women. What they don’t realize is that they could be sharing Matt Damon or Bill Gates with other women.

Once we begin to look at things through the lens of evolutionary psychology and biology, they start to look quite different. Something that we previously thought was quite bizarre and morally wrong, like polygyny, begins to look quite natural and common. The perspective also gives us a new insight, like how women, not men, mostly benefit in polygynous societies.

About the Author

Satoshi Kanazawa is an evolutionary psychologist at LSE and the coauthor (with the late Alan S. Miller) of Why Beautiful People Have More Daughters.