When it comes to picking out a mate, new research suggests women may be looking for chiseled abs, not a square jaw.
Manly features like a strong jaw and squinty eyes have long been assumed to appeal to potential mates — perhaps because they typically indicate that those who possess them can maintain strong immune systems. But studies testing the relationship between masculinity and appeal have produced mixed results, according to research published in the Nov. 27 issue of the journal Proceedings of the Royal Society B.
So, the researchers tested whether weight could serve as a driver of attraction. They found that while women do respond more favorably to the faces and bodies of men with strong immune responses, they use fatness and thinness to cue them in on how fit a man is, not macho features, according to Livescience.com.
Fatness, or adiposity, "is an obvious choice for a marker of immunity because of its strong association with health and immunity," study researcher Vinet Coetzee, a postdoctoral scientist at the University of Pretoria in South Africa, told LiveScience.
Coetzee and his colleagues wrote that weight is consistently linked both to health and having a healthy immune system — while studies haven’t consistently linked macho features with good physical health.
To test the theory, the researchers took pictures of 69 Caucasian male volunteers in underwear. They also measured the men’s body fat and testosterone levels. Around 65 of the volunteers were a healthy weight, 4 percent underweight and 30.4 percent overweight. Their immune system response was also measured with a blood test after they received a vaccine for hepatitis B (the men with strong immune responses showed more antibody production after the vaccine than those with weaker immune systems).
Then, 29 heterosexual Latvian women looked at the pictures of the men’s faces and bodies separately and judged them on attractiveness.
A separate group of 20 heterosexual Finnish men and women rated the men for masculinity, and 14 other Latvian women rated the men’s facial fatness, which is related to overall body fatness.
The researchers found that the fatter men had weaker immune systems and were seen as less appealing by the women. Masculinity on the other hand was not linked to either immune response or bodily or facial attractiveness.
"We found that a man’s weight serves as a better indicator of the relationship between immune response and attractiveness than masculinity does," Coetzee said. "It is therefore more likely that Latvian women use weight, rather than masculinity, in their subconscious judgments of a man’s immunity."