Gender Ratios and the Math of Romance

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Biologists and zoologists have been studying animal sex ratios since the days of Charles Darwin, but the pioneering scholarly work on human gender ratios was not published until 1983. Too Many Women?: The Sex Ratio Question was the brainchild of psychologist Marcia Guttentag, a professor at Harvard University. The book was completed and co-authored by Paul Secord, Guttentag’s second husband and a professor at the University of Houston, following Guttentag’s sudden death in 1977 at the age of 44.

Too Many Women’s big idea was an audacious one — “that the number of opposite-sex partners potentially available to men or women has profound effects on sexual behaviors and sexual mores, on patterns of marriage and divorce, childrearing conditions and practices, family stability, and certain structural aspects of society itself.” A psychologist and academic on the front lines of the feminist movement, Guttentag found herself struggling to understand a sudden rise in suicide and depression among young women in the 1960s and 1970s. Her epiphany came, oddly enough, after a night at the opera.

In the preface of Too Many Women, Guttentag recalls taking her teenage daughter, Lisa, to see Mozart’s The Magic Flute performed in English and then being thunderstruck by the lyrics. Guttentag notes how each of the male protagonists “sings of his determination to find a wife and of his longing to make a commitment to a woman for life ... The intensity of their desire is demonstrated by their willingness to undergo severe trials in order to enter Sarastro’s brotherhood and claim their respective loves.” Curious, Guttentag asked her daughter if she noticed anything odd about the lyrics. Her daughter’s response: The lyrics were “strange” because the men sang “about wanting to make a lifelong commitment to one woman — a wife.”

Both mother and daughter observed similarities between The Magic Flute and the idealized depiction of women in popular American songs of the 1930s, ’40s, and ’50s — before America’s gender ratio swung from more men than women to more women than men. (Prior to World War II, immigrants to the U.S. were disproportionately male.) Guttentag grew up in the 1930s and ’40s, and the pop lyrics of Guttentag’s youth had always emphasized “romantic love, exclusive commitment for life, marriage, and monogamy.” By the 1960s and ’70s, however, music’s romantic themes had given way to a more sexualized "'love 'em and leave 'em’ ethos." In contemporary lyrics, she observed, “there was no sign of a male’s intention to make a long-term sexual commitment, and marriage was never mentioned.”

Why? Guttentag wondered. “Why the difference between Mozart’s lyrics two centuries ago and our lyrics today?” One striking possibility came to mind: “Are there too many unattached women? Is there actually a shortage of men? If there is, could this possibly explain all of these changes?”

Guttentag was onto something. As she and Secord would show, the national sex ratio for marriage-age Americans swung from more men to more women during the decade intervening the 1960 and 1970 censuses. Back then, women typically married men three or four years their senior, and the post–World War II Baby Boom meant there were many more women born in 1946, 1947, and 1948 than there were men born in 1943, 1944, and 1945. On account of this — and on account of the generally rising number of births from 1945 through 1957 — American women born in this era got caught in what would later be known as “the marriage squeeze.” A dating market that had been 111 marriage-age men for every 100 marriage-age women in 1960 evolved into one with 84 men for every 100 women in 1970, according to Guttentag and Secord.

In order to understand the implications of this demographic shift, Guttentag spent years poring through Census numbers, sex-ratio data, and other historical materials dating all the way back to ancient Greece and medieval Europe. Her and Secord’s conclusions? In societies in which men outnumbered women, the prevailing culture was more likely to emphasize romance and courtship. Men must compete for a wife and thus they were more willing to make and to keep a commitment to remain with her. And while women in such societies did tend to play rather stereotypical roles of “homemaker and mother,” the high ratios of men to women gave women the power to “choose among men for a marriage partner.” This, Guttentag and Secord concluded, “gives women a subjective sense of power and control” since they are highly valued by men as “romantic love objects.”

The story changed, though, when the women outnumbered the men — just as it did in the animal kingdom. When men were the ones in undersupply, women were “more likely to be valued as mere sex objects,” according to Guttentag and Secord. One upside for everyone was that the quality and variety of sex seemed to improve. Clinical sex studies observed “a real increase in and diversification of erotic activity” as twentieth-century gender ratios began to skew female, they wrote. “Coital frequency and length of intercourse have both increased substantially, as has length of foreplay.”

A second upside: Historically, when men were scarce, women were more likely to attain political rights and economic parity. For example, in ancient Sparta, where the ratio of men to women was low, women were highly educated and controlled two-fifths of land and property.

For women, however, the advantages associated with too few men did not erase the problem of diminished marriage prospects. In the too-many-women societies, the culture did not emphasize love and commitment, Guttentag and Secord concluded. Sex outside of marriage became the norm and out-of-wedlock births commonplace. “The outstanding characteristic of times when women were in oversupply would be that men would not remain committed to the same woman throughout her childbearing years.” More men and women remained single because men had less incentive to settle down. And when couples did marry, they were more likely to get divorced.

For men and women alike, “sexual libertarianism” became “the prevailing ethos” of the day. “Brief liaisons would be usual, as men would have opportunities to move successively from woman to woman or to maintain multiple relationships with different women.”

Sound familiar?

Excerpted from Date-onomics: How Dating Became a Lopsided Numbers Game, Copyright 2015 by Jon Birger. Used by permission of Workman Publishing Co., Inc. New York. All rights reserved.