Men more likely to stick with girlfriends who sleep with other women than other men

Women show the opposite pattern. They are more likely to continue dating a man who has had a heterosexual affair than one who has had a homosexual affair.

The study, published last month in the journal Personality and Individual Differences, provides new insight into the psychological adaptations behind men's desire for a variety of partners and women's desire for a committed partner. These drives have played a key role in the evolution of human mating psychology.

"A robust jealousy mechanism is activated in men and women by different types of cues -- those that threaten paternity in men and those that threaten abandonment in women," says Jaime C. Confer, the study's lead author and a doctoral candidate in evolutionary psychology.

Confer conducted the study with her father, Mark D. Cloud, a psychology professor at Lock Haven University in Pennsylvania.

The researchers asked 700 college students to imagine they were in a committed romantic and sexual relationship with someone they've been dating for three months. They were then asked how they would respond to infidelity committed by the imagined partner.

Some participants were told their partners had been unfaithful with a man, others with a woman. Some were told their partners had an affair with one person, others with multiple partners. Some were told the infidelity happened once, others twice.

Regardless of the number of episodes or partners, the study found that:

• Overall, men demonstrated a 50 percent likelihood of continuing to date a partner who has had a homosexual affair and a 22 percent likelihood of staying with a woman after a heterosexual affair.
• Women demonstrated a 28 percent likelihood of continuing to date a boyfriend who has had a heterosexual affair and a 21 percent likelihood of staying with someone who has had a homosexual affair.

The findings suggest men are more distressed by the type of infidelity that could threaten their paternity of offspring. Men may also view a partner's homosexual affair as an opportunity to mate with more than one woman simultaneously, satisfying men's greater desire for more partners, the authors say.

"These findings are even more remarkable given that homosexuality attitude surveys show men have more negative attitudes toward homosexuality and to be less supportive of civil rights for same-sex couples than women. However, this general trend of men showing lower tolerance for homosexuality than women is reversed in the one fitness-enhancing situation -- female homosexuality," say the authors.

Conversely, women objected to continuing a relationship following both types of affairs, but especially so for a boyfriend's homosexual affair. Such an affair may be seen as a sign of dissatisfaction with the current relationship and a prelude to possible abandonment, according to the authors.

Participants were also asked the outcomes of real-life infidelity experiences. Results mirrored those of the imagined infidelity scenarios: Men were significantly more likely than women to have ended their actual relationships following a partner's (presumably heterosexual) affair.