Daniel Kruger of the University of Michigan School of Public Health and colleagues examined the ratio of men to women in the 50 largest U.S. metropolitan statistical areas using U.S. Census data from 2000.
"Women don't stay on the market long because men are more motivated to commit," Kruger said in a statement. "They want to secure the relationship before some other guy gets her."
Each gender has a somewhat different reproductive agenda -- women want a reliable, stable provider because it benefits their children, but men may have to build up their social status and resources before they are considered marriageable, Kruger said.
As a result, the marrying age for men varies more widely when women are scarce, because younger men often have to wait until they accumulate enough to compete for a mate, Kruger said.
For example in Las Vegas, where there are six men for every five women, the median marrying age for men is 28.3 and for women is 24.5, but in Birmingham, Ala., where there are 11 women for every 10 men the median marrying age for men is 26.9 and for women 26.7.
The findings are published in the journal Evolutionary Psychology.