“I never saw a woman worth thinking twice about after the anchor was a-peak—on shore it is another thing; and I will laugh, sing, dance, and make love, if they like it, with twenty girls.”—Clement Cleveland, in Walter Scott’s “The Pirate”

For long-term relationships, women like dads—men who are kind, compassionate and monogamous. But for short-term relationships, women prefer cads—the classic Romantic dark heroes who are dominant, promiscuous and daring.

That’s according to a new U-M study, appearing in the current issue of the journal Human Nature.

“About 60 percent of the women said they would prefer to have sex with a cad when considering a brief affair,” says Daniel Kruger, a social psychologist at the Institute for Social Research (ISR).

Kruger and co-authors Maryanne Fisher and Ian Jobling tested evolutionary mating theories using hypothetical scenarios involving classic cad and dad character types from 18th and 19th century British literature. The subjects were an ethnically diverse group of 257 female undergraduates at a large Midwestern university.

“About 60 percent of the women said they would prefer to have sex with a cad when considering a brief affair.” —Researcher Daniel Kruger

The women read passages from Romantic novels describing two prototypical dads and two prototypical cads, and answered a series of questions. While the women said they preferred dads for long-term relationships, they found cads more desirable as short-term mates. Their tendency to choose cads over dads increased as the length of the hypothetical relationship decreased.

Kruger says the findings imply that the dad versus cad distinction is intuitive to women and remains a key element of contemporary mating strategies. Women’s preference for cads for short-term relationships supports what evolutionary psychologists call the “sexy son hypothesis,” Kruger says. Even though cads aren’t good bets to stick around and help raise children, the genes that make men successful cads will be passed along to their sons, who will increase their mothers’ eventual reproductive success by providing numerous grandchildren.

Finally, Kruger notes, the distinction between dads and cads is intuitive enough that women showed a strong preference for dads as potential sons-in-law. Only 13 percent of the women said they would prefer to see an imagined 25-year-old daughter engaged to a cad. “A cad would be less likely to provide paternal support for offspring,” Kruger says, “which means that a daughter might turn to the maternal family for help. That could adversely impact the grandmother’s overall reproductive success.”