Although many men say a well-rounded booty is simply more attractive, some evolutionary psychologists believe it goes way deeper than appearance. Studies suggest our male ancestors were attracted to a larger behind because they believed it increased the likelihood of having healthy kids. It is also believed by some that these mating preferences still prompt men on a primal level.
A 2015 study published in the Evolution and Human Behavior journal examined how the mating preference in men evolved to favor women with a more prominent backside. The hypothesis of the research team was not entirely about the mass of the cheeks which gives the shape a meaningful indication for female fertility. The hypothesis also discussed the extent that the booty protrudes from the body due to the curvature of the spine.
It was noted that women with straight spinal columns are at a disadvantage when it comes to reproduction since their center of mass shifts forward and puts excess pressure on their muscles and lower back. This physical characteristic increases the level of pain as well as the risk of injury. However, women with adequate curvature of the lower vertebrae are more likely to uphold a center of mass over their hips and provide more stability while reducing the risk of injury. Researchers hypothesized that women with more prominent buttocks due to lower lumbar curvature would prove to be more attractive. To determine if they were correct, the researchers conducted two studies to see if men like bigger butts.
The first study involved morphing photos of women whose appearance was identical except for the degree of spine curvature. The images presented a curve of the lower back ranging from 26-degrees to 61-degrees. The study included 102 male college students who viewed the images and rated the models by attractiveness. It was determined that 45.5-degrees, which is the optimal level according to orthopedic medical research, proved to be more attractive. Researchers found that the attractive ratings decreased after the 45.5-degree mark was exceeded. It should be noted that excessive curvature has a host of potential health issues and risks so it makes sense that the preferred curvature is only attractive up to a certain point.
For the second study, researchers wanted to determine if the lumber curvature is the basis of attraction or if men just like big butts. During this study, 202 male college students were exposed to a series of female figure morphs. The digital images portrayed a female who had the same size butt but looked different due to having larger gluteal muscles, fatty tissue or lumbar curvature. According to the researchers, the study showed that men prefer a woman with a curvy spine and not necessarily one with a larger derriere.