College students with an absent father are more likely to engage in casual sex, according to new research published in the journal Evolutionary Psychological Science.

The study, conducted by Catherine Salmon of the University of Redlands along with her colleagues John M. Townsend and Jessica Hehman, examined the relationship between a father’s absence and the sexual behavior of college students.

“There is a large amount of literature on life history strategy and psychosocial acceleration theory that suggests a strong impact of father absence on female sexual strategies and some evidence, from this new study and a few others, that it also impacts male sexual behavior,” Salmon told PsyPost in an email.

The researchers recruited 344 undergraduate students (91 men and 247 women) from psychology courses at two private universities and had them complete a scientific survey online. All of the students were between 17 and 40 years of age.

Salmon and her colleagues found no significant difference between men and women when it came to the number of sex partners in the last 12 months. But, overall, men tended to have had more one-night stands than women.

The researchers failed to find a relationship between an absent father and number of sexual partners. But they did find a link between an absent father and number of one-night stands.

The earlier the students were no longer living with their biological father, the greater the number of one-night stands. This was true for both men and women. “Thus, father absence was a clear predictor of short-term reproductive decisions that affected both males and females, rather than a specific effect on females,” the researcher noted.

Salmon and her colleagues looked to a body of research known as life history theory to explain their findings.

According to life history theory, early life experiences can shape an individual’s expectations about the nature of other people, relationships, and life in general. Those faced with high stress, scarce resources, and insensitive parenting in early life develop a “fast life” strategy that typically includes “insecure attachment, early maturation, early sexual activity, and an emphasis on short-term mating.” In other words, people who grow up in an unstable environment learn to focus on immediate benefits, since the future is uncertain.

Salmon and her colleagues also found differences in how men and women perceived casual sex. Women were more likely to be concerned with their partners’ sexual intentions and feel vulnerable. This finding, they said, supported a key tenet of evolutionary psychology known as parental investment theory.

Evolutionary psychology predicts that men and women will tend to have different mating strategies because of a simple fact: Women get pregnant and men do not. This fundamental asymmetry means men and women face different challenges in regards to their reproductive fitness (meaning the number of surviving offspring they produce.)

Women will tend to prefer long-term, committed mates, according to the theory, because gestation and breastfeeding force women to invest more time and resources in their children.

Salmon and her colleagues found that women were more likely than men to agree with statements such as “Whenever I have sex with someone, I wonder if sex was all he/she was after,” “If I have sex with someone I feel vulnerable afterwards,” and “If I have sex with someone I don’t really know, I would at least like to know he/she cares.”

“From a sexual strategies perspective, such reactions would be designed to make females cautious about engaging in sexual relations, particularly with men unwilling to invest time, affection, or resources,” the researchers wrote.