In the town where you live, are there more women or men?  If you’re a woman living in Washington, D.C., New York, Miami, Boston, or Chicago, you’re in the majority, but if you’re living in Denver, Tucson, Norfolk, Fort Lauderdale, or Salt Lake City, you’re in the minority.  It’s sometimes bad to be a minority, but not when it comes to getting a date.  And it turns out, there are unpleasant economic consequences of being in the majority, especially if you’re a man.  Men confronting a male-biased sex ratio are less likely to save, more likely to take on credit card debt, and willing to take bad financial deals just to quickly get their hands on some money now, according to a new series of studies by researchers at the University of Minnesota, Free University of Amsterdam, MIT, UC Santa Barbara, and Arizona State University.  

 According to the lead researcher, University of Minnesota’s Vlad Griskevicius, the research was inspired by findings from other animal species, demonstrating that a whole host of behaviors, across a wide range of species, are triggered by imbalances in sex ratios.  Because female animals generally have an easier time finding a mate than do males, the consequences are generally more severe for male animals.  When there are too many male grey mouse lemurs, each of the little primate fellows needs to amp up his game, if he hopes to win the competition for those cute little grey mouse lemur-ettes.  The same has been found in many other species of mammals, birds, and fish.  Research with humans has found that male violence also increases with male-biased sex ratios.  On the other side of the equation, women have to work harder to find and keep a man when the population is female-biased. 

Griskevicius and his colleagues (Josh Tybur, Josh Ackerman, Andy Delton, Tess Robertson, and Andrew White) reasoned that the links between sex ratios and sexual competition might have indirect influences on economic behavior.  A great deal of research has shown that women are more attracted to men with financial resources.  More recent research has demonstrated that men who are inspired to find mates are more likely to take financial risks (see my recent postings describing other new findings linking loss aversion and conspicuous consumption to mating motives).  As Griskevicius notes:

“A male-biased sex ratio means men need to compete for mates.  Given that a man is more likely to attract a woman if he advertises his financial resources by spending and conspicuously consuming, we predicted that we would see men becoming more economically impulsive when the sex ratio is tipped toward men.” To test these ideas, the team conducted four studies, recently released online by the Journal of Personality of Social Psychology

The first study examined the correlation between the number of credit cards and the average amount of consumer debt across 134 American cities.  Indeed, a city’s sex ratio predicted the degree of credit card debt (more men than women = more debt).  That study, though consistent with their reasoning, did not allow the researchers to determine whether it was men or women who were spending more, so they moved to the laboratory to get a clearer causal picture.

In their second study, the team showed people photographs of crowds of students.  Some people saw photographs in which the majority of people were men, others saw photos in which the majority were women.  The subjects next played a game in which they were entered into an actual lottery.  If they won, they would get one of the amounts they had chosen from a series of choices, such as "$30 tomorrow or $60 in 33 days."  Sex ratio had no effect on women’s choices, but men who had seen a lot of other men made more impulsive “give me the money now” choices.

In the third study, students read an article from the Chicago Tribune, which either argued that there would be more women or more men in the mating pool over the next few years.  One headline read, for example, “Fewer Women for Every Man for Today’s Students.” Another reversed to say there would be fewer men for every woman.  Afterwards, the students were asked to imagine that they had a post-graduation job that left them $2000 to cover various expenses, such as housing, food, transportation, and entertainment.  They were asked a) how much of their monthly take-home income they intended to set aside for savings, and b) how much they would be comfortable borrowing on a credit card if they had little or no disposable income left.  A male-biased sex ratio inspired men to cut their yearly savings by $756, and to up their credit card debt by $372. See the figure.

Willingness to Incur Debt as a function of sex ratios

In the final experiment, the researchers asked students how much they thought a man should spend on a Valentine’s gift, on buying a date’s meal in a restaurant, and on a diamond engagement ring.  Again, men who had just read about a male-biased sex ratio expected to spend more on all these things.  Although the previous studies had found that women did not change their own spending in response to sex ratios, this study revealed that women were not oblivious to sex ratios.  In fact, women boosted the amount that they thought a man should spend on gifts, meals, and engagement rings if they’d just read about a male-biased sex ratio. 

These findings reveal yet another aspect of human decision-making that can be better understood by examining ourselves in light of what biologists have revealed about the rest of the animal kingdom.  Male peacocks do not have credit accounts, but if they did, they would no doubt pin their Amex platinum cards to their tails during the mating season.  

Douglas T. Kenrick is author of Sex, Murder, and the Meaning of Life: A psychologist investigates how evolution, cognition, and complexity are revolutionizing our view of human nature.

Related Links:

How a passing mood can profoundly alter your economic decisions.

Deep Rationality 2: Conspicuous Consumption as a Mating Display.

Deep Rationality: Evolutionary psychology meets behavioral economics


Griskevicius, V., Tybur, J. M.; Ackerman, J.M.; Delton, A. W.; Robertson, T. E.; White, A. E. (2012).  The financial consequences of too many men: Sex ratio effects on saving, borrowing, and spending.  Journal of Personality & Social Psychology, in press. Early online release.  doi: 10.1037/a0024761.

Li, Y.J., Kenrick, D.T., Griskevicius, V., & Neuberg, S.L. (2012).  Economic biases in evolutionary perspective: How mating and self-protection motives alter loss aversion.  Journal of Personality & Social Psychology.   Early online release:

Sundie, J.M., Kenrick, D.T., Griskevicius, V., Tybur, J., Vohs, K., & Beal, D.J. (2011). Peacocks, Porsches, and Thorsten Veblen: Conspicuous consumption as a sexual signaling system. Journal of Personality & Social Psychology, 100, 664-680

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