A new study has shown that marriage rates in places where women outnumber men are less likely to rise, as the young men feel less pressure to settle down because more women compete for their affections.
However, the same study suggests that when these men reach their 30s, the reverse becomes true and proportionately more older men are married in areas where women outnumber men.
These finding have been made by Daniel Kruger, a University of Michigan researcher who studies evolution and how it relates to contemporary behaviour.
For the current study, Kruger looked at the 50 largest metropolitan areas in the US to test his hypothesis on how the balance between women and men affects marital patterns.
The researcher found that men aged 20-24 were more likely to cruise than to commit if they lived in an area with more women than men.
While one would think that, rationally, fewer young men than women would naturally lead to proportionately more young men getting married, Kruger says that that is not the case.
"Marriage patterns aren't rational because men and women have somewhat different reproductive strategies. Men have a greater reproductive benefit than women from having a greater quantity of relationships.
If they can leverage their scarcity into attracting multiple short-term partners, they will not have as much of an incentive to settle down," Kruger said.
According to his study, there are about nine unmarried men for every 10 unmarried women in Birmingham, Memphis, New Orleans, and Richmond-Petersburg, Virginia.
Kruger further points out that Philadelphia, Washington, DC, Baltimore, and New York metropolitan areas are tied for the next region where women are relatively most plentiful. In these areas, about 84 percent of the men aged 20-24 are unmarried.
In Las Vegas, San Diego, Salt Lake City, Austin, and Phoenix, there are about nine unmarried women for every 10 unmarried men. In these areas, about 77 percent of the men aged 20-24 are unmarried.
Once those young men hit their 30s, they tend to shift from seeking short-term relationships to entering into committed relationships-because when women evaluate partners for short-term relationships, they value physical features signalling the kind of genes that would be passed on to potential offspring, which may be the only legacy of men who don't stick around for child rearing.
These physical features decline as men age, making it more difficult to lure women into uncommitted relationships.
Kruger says that these findings do not mean that middle aged women in these cities get a break. The researcher points out that the higher marital rates for older men likely benefit women who are substantially younger than their husbands, as older men still prefer partners with higher reproductive potential.
The study has also shown that hemlines actually rise in areas with more women than men, as women do more to physically attract men.
It further shows that the rates of divorce and out-of-wedlock births are higher, and interests in women's rights increases. Surpluses of men tend to be associated with more conservative social norms and restricted roles for women.
The findings have been reported in the Journal of Social, Evolutionary and Cultural Psychology and Evolutionary Psychology.