The research report, titled “The Financial Consequences of Too Many Men: Sex Ratio Effects on Saving, Borrowing and Spending,” proposes a theory that sex ratio affects economic decisions. In the animal world when females are scarce, males become more competitive for access to mates. The researchers propose that sex ratio also has pervasive effects in humans, such as influencing economic decisions.
As part of the research, participants read news articles that described their local population as having more women or more men. After reading, they were asked how much money they would save from a paycheck and how much they would borrow with credit cards. When women were scarce, the savings rates for men decreased 42%.
In another study, participants looked at photos with different gender proportions and were asked to choose between receiving $20 tomorrow or $30 in a month. When women were scarce, men tended to take the money immediately.
Women’s financial choices were not affected by sex ratios, but a scarcity of women led people to expect men to spend more money during courtship, such as paying more for engagement rings.
The researchers also calculated sex ratios of more than 120 U.S. cities and found that communities with lots of single men had more credit cards and higher debt.