Dating is a numbers game when is comes to how much men are willing to spend, according to a new study led by University of Minnesota's Vladis Griskevicius.

Sex ratio, or the number of single adult men versus adult women, impacts economic decisions such as how much a man is willing to save, spend, and borrow, the study found.

The fewer women there are, the less likely men will want to save for the future, and the more likely they'll be to take on debt. That is, they'll spend more impulsively when they sense there's a shortage of women.

Of course this is biological, says Griskevicius:

"A male-biased sex ratio increases the degree to which men must compete for mates, and given the importance for men of advertising financial resources via spending and consumption, we predicted that shifts in sex ratio would be associated with men’s desire for immediate gains."

To test the theory, researchers gathered data in over 120 U.S. cities, including how many credit cards the average resident owned, and how much debt they were carrying. Both behaviors, they say, "are indicative of overspending and impulsivity." Then they examined where sex ratio came in.

The researchers asked 205 individuals (104 female) around the median age of 21.5 years-old to view a series of nature images and headshots. After being told the photos were either of people from a local dating site, recent graduates still living in the area, or people currently on campus, the participants were asked to record the number of men and women they viewed. Then they were asked to make a money decision: Would they'd prefer to receive $35 tomorrow or $45 in 33 days?

The men who sensed a shortage of women said they wanted the money tomorrow, whereas those who felt differently were fine with putting off the pay day until later. The same also applied with regards to saving—men who noticed fewer women around told researchers they were less inclined to put money away in the bank.