How the Woman/Man Ratio Affects Sex, Facial Hair, and Politics

In the 1970s, a Harvard psychologist proposed that the ratio of men to women shapes culture and politics. Her theory predicts U.S. social trends for the next 25 years.

By Robert Epstein|Thursday, October 04, 2012

It may be hard to believe in the midst of another contentious election cycle, but the next quarter century in the United States promises to be a period of increasing moderation and stability—at least according to a little-known but compelling theory about how the ratio of available men to available women alters our lives.

Ups and Downs of America's Sex Ratio


Harvard social psychologist Marcia Guttentag began formulating her theory in 1975, after watching Mozart’s The Magic Flute with her second husband, psychologist Paul Secord, and her two children, Lisa, 16, and Michael, 14. “Nothing is more noble than wife and man, man and wife, and wife and man … [reaching] to the height of Godliness,” sang Papageno and Pamina onstage. Hearing them extoll the virtues of marriage so extravagantly put Guttentag into a kind of “cultural shock,” she later wrote. These were the 1970s, after all, when millions of marriages—including both Guttentag’s and Secord’s first marriages—had collapsed in the chaos of the free love movement spawned during the previous decade.

When Guttentag returned home, she and her daughter listened to songs that were popular at the time, all of which had a “love ’em and leave ’em” theme. Why were views on marriage in these two eras—Mozart’s 1790s and America’s 1970s—so very different? Maybe, she conjectured, women were in short supply in Mozart’s day, and perhaps now, in the 1970s, there were just too many women.

That became the title of a book Guttentag began writing soon after she had her insight, which she knew was the most important of her career. For the first time in U.S. history, she soon learned, the “availability sex ratio”—the ratio of adult men to adult women who are available to marry—had dropped well below 1.0, to perhaps 0.7 by 1970. This meant that there were now 10 available women for every 7 available men, an excess of millions of women of marrying age. What had caused the sex ratio to drop so 
dramatically, Guttentag wondered, and what impact did this change have on society?

While busy directing two research centers at Harvard University, Guttentag began Too Many Women as a true labor of love. She examined imbalances in the ratio of men to women in various cultures and at various times throughout history and the effects they had on social systems. Among other things, she found that where the sex ratio was high, marriage was stable and women tended to stay home, but where the sex ratio was low (too many women, that is), 
marriage was unstable and women moved into the workplace.

The dramatic differences between Sparta 
and Athens during the fourth century B.C. drove the point home for Guttentag. Ancient Athens most likely had a sex ratio between 1.43 and 1.74 (based on a historical analysis) because of rampant female infanticide and neglect. With three men for every two women, women were kept uneducated and at home. Sparta, in contrast, was a military state in which males were removed from their families early on to be trained as soldiers. With an extreme shortage of men in Spartan society, girls received educations and even physical training similar to that of boys, and women controlled and inherited property. Fourth century B.C. Spartan women controlled 40 percent of the land and property in Sparta; Athenian women controlled no property at all.

But Guttentag’s book was not to be, at least not the way she planned it. On November 4, 1977, just five days short of her 45th birthday, she died from a heart attack while alone in a hotel room in New York City. Her husband, Paul, completed her manuscript, but the book that finally came out in 1983 was academic in nature, not the mainstream “big think” book she intended. With her death, the book deal she had made with a major publisher disappeared, and sex ratio theory stayed mainly in the obscure recesses of various academic specialties.

Biologists have looked at the sex ratio in animal populations for generations, typically just by counting the males and females in a pack or herd. The natural sex ratio for the American alligator, for example, is about 0.2, or one male for every five females. That kind of ratio makes sense when males fight a lot and female fertility is low.

To study the sex ratio in humans is more challenging, especially if your goal is to determine how the sex ratio affects social systems. Nigel Barber, an evolutionary psychologist based in Birmingham, Alabama, has tested its power more than any other scholar. Among his recent findings: When the sex ratio is low (too many women), women are more slender; when women are in short supply, as was the case in the United States in the 1950s, women are more curvaceous, perhaps because they are trying to look the part of traditional wife and mother. Barber’s studies, which often look at patterns in 40 countries or more, have shown the power of the sex ratio in predicting such things as the rate of nonmarital births, the practice of polygyny, and even the likelihood that men will grow facial hair. The more men there are, he found, the more hair they grow to attract mates.

United States Births, 1940-Present

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