Simply by looking at a photo, most people are able to figure out if a person would be good in a monogamous relationship or if that person is more interested in casual sex, Mairi Macleod writes for the New Scientist. Men who look more “masculine” and women who are judged more “attractive” were not only thought to be more promiscuous, they actually were more inclined toward flings.
Scientists are trying to explain this phenomenon through biology and evolution. The ability to make accurate snap judgments of people’s sexual proclivities would provide an evolutionary advantage. What scientists continue to grapple with, however, is why people would have such wildly divergent sexual strategies to begin with.
Back in 1991, researchers developed a questionnaire to measure people's level of sexual unrestrictedness, a trait they called “sociosexuality.” Survey respondents were asked seven questions, including questions about their sexual history and if they agreed with statements like, “Sex without love is OK.” From their answers, researchers tried to determine how cavalier respondents were toward sex. You can view the questionnaire here.
From that questionnaire, evolutionary biologists identified differing motivations for infidelity between men and women. Since women run the risk of getting pregnant, men are thought to be evolutionarily wired for more sexual partners. This may be changing, however, according to new research profiled in the New York Times. Tara Parker-Pope writes that “women appear to be closing the adultery gap: younger women appear to be cheating on their spouses nearly as often as men.”
That may be true in the United States, but many factors are at play that could influence the numbers. For example, in cultures with a high ratio of men to women, like China, Japan, and South Korea, “there is a relatively low level of interest in uncommitted casual sex,” according to Macleod. And Parker-Pope reports that social taboos may influence self-reporting of infidelity, where people are less apt to admit infidelity during in-person surveys.
In their quest for more accurate answers on enduring sexual questions, scientists continue to dream up stranger and stranger experiments. In her new book on sexual science, Bonk, author Mary Roach describes the act of having sex with her husband in a 4D ultrasound system, and some experiments even stranger than that. Although the science still leads to unreliable results, Roach told the website Neuronarrative, “we’ve come a long way, certainly. That’s not to say that the work is done, though.”