Check out
this study out of the University of Minnesota: "The perception that women are scarce leads men to become impulsive, save less, and increase borrowing."
"To test their theory that the sex ratio affects economic decisions, the researchers had participants read news articles that described their local population as having more men or more women. They were then asked to indicate how much money they would save each month from a paycheck, as well as how much they would borrow with credit cards for immediate expenditures. When led to believe women were scarce, the savings rates for men decreased by 42 percent. Men were also willing to borrow 84 percent more money each month."
Sex ratios also affect women's expectations, according to the study. When there's a scarcity of women, they expect men to spend more on dates, valentine's gifts and engagement rings. Apparently, the two-months-of-your-salary rule no longer applies when the sex ratio goes your way!