Men and women viewed photos of the opposite sex twice and were asked to rate each person’s level of attractiveness both times for a study published in the Archives of Sexual Behavior. The result? Women rated the photos more attractive the second time, while men rated them more attractive the first time, suggesting a male preference for novelty, and a female preference for familiarity. The plot thickens: In a second study, men found women more attractive if they looked less like their current partner (the results were the opposite for women). Major womp. “Generally, familiarity is attractive because it means you know how people will behave,” says Andrew Little, research fellow in the school of psychology at the University of Stirling, and author of the study. “But men seem to prefer novelty when it comes to women’s faces, presumably due to evolutionary pressures to increase their number of offspring.” Meaning, you guessed it, he wants to spread his seed with women he hasn’t been with already. But we’ve heard this song before: Men want to, um, maximize their genes (is that what they’re calling it?), and women want a man that stays around to help raise kids. So, does evolutionary research really mean men are destined to stray? “Research suggests that both men and women cheat on their partners at least occasionally,” says Little. And for a lot of reasons: jealousy, unhappiness in the relationship, power, attention seeking, the list goes on. This study doesn’t mean he’s secretly out having one-night stands—and it certainly doesn’t make “Sorry, baby, it’s evolution!” an acceptable excuse if he is. More from Prevention: Why Women Cheat