A: suitable guys around to date.

Women are studying and working much harder because of men or rather, a lack of them. Researchers say women tend to go to college and pursue better careers when there are not enough suitable guys around to date. “Women who judged themselves to be less desirable to men, those who are not like Angelina Jolie, were most likely to take the career path when men became scarce,” says University of Texas at San Antonio’s Kristina Durante, who with Vlad Griskevicius of the University of Minnesota examined the ratio of single men and women in various states. They found that in places with fewer bachelors, the percentage of ladies looking for high paying professions increases, as they decide to wait to have children. Notes Griskevicius: “A scarcity of men leads women to invest in their careers because they realize it will be difficult to settle down and start a family.”