New research provides evidence that women consider a “lordotic” posture (in which the lower spine is curved towards the belly) in other women as a signal of heightened sexual receptivity, and perceive women exhibiting this posture as a potential threat to their romantic relationship. The new findings have been published in the journal Sexes.
Lordosis behavior is a natural mating posture displayed by female mammals, which is a critical component of successful reproduction. It involves the female arching her back and lifting her hindquarter. While the lordotic posture is primarily observed in non-human animals during mating, some researchers have proposed that a similar posture may have evolved as part of courting behavior in humans.
In previous research, Farid Pazhoohi (a postdoctoral fellow at the University of British Columbia) and his colleagues demonstrated that men are captivated by the arched back of a woman. They created six realistic computer-generated 3D models of a woman’s body with slightly different angles of curvature in the back and presented them to 82 undergraduate men and women to rate for attractiveness.
Results showed that the more arched the back of the 3D model, the more attractive it was rated. Eye-tracking technology revealed that men looked at the hip regions of the models for longer periods of time as the curvature increased.
In a series of three similar studies, published in Adaptive Human Behavior and Physiology, Pazhoohi and his colleagues found that lordotic posture in women was associated with higher ratings of sexual receptivity as well. This was true regardless of whether the women were standing upright, on their hands and knees (quadruped position), or lying down on their back (supine position). But a similar effect was not observed for men’s arched back postures. The studies included 612 heterosexual individuals.
“It suggests that an arched back posture in women is perceived as an indicator of sexual receptivity by both men and women across different body postures,” Pazhoohi explained.
For their latest study, the researchers were interested in the relationship between lordosis and intrasexual competition in women, which refers to competition between women for access to desirable male partners. They conducted three studies to investigate the role of intrasexual competitiveness in how women perceive lumbar curvature.
In the first study, 138 heterosexual women (aged between 19 and 79 years) completed an assessment of intrasexual competition. They then viewed 3D models of standing women with different angles of curvature in the back and rated their perceived sexual receptivity.
The researchers found that women’s intrasexual competition was positively associated with their perception of sexual receptivity. Women who agreed more strongly with statements such as “I can’t stand it when I meet another woman who is more attractive than I am” tended to perceive the female models as having higher sexual receptivity.
In the second study, which included 69 heterosexual women (aged between 19 and 78 years), the researchers “extended the findings to non-standing poses of supine and quadruped and again found women perceived an increase in arch of the back as more sexually receptive, which was influenced positively by their intrasexual competitiveness,” Pazhoohi told PsyPost. “This indicated that women are more wary of more receptive women not only in a standing posture, but also in other postures.”
In the third study, which included 106 heterosexual women (aged between 23 and 70 years), the researchers presented the participants with images showing women in different postures. The participants were asked to imagine that their romantic partner had asked to see a photo of their friend. They were then presented with two options and asked to choose which photo they would show to their partner and which one they found more attractive. The two options presented differed in the degree of lumbar curvature.
“Finally, the third study found that women perceive other women in more arched-back postures as more threatening to their relationships, and they were less likely to show such images to their partners,” Pazhoohi said. “Overall, these findings suggest that lordosis posture is a signal of sexual receptivity in women and that this signal can trigger feelings of competition and threat among other women.”
The findings shed light on the relationship between women’s lordotic posture and intrasexual competition. However, the new research includes some limitations. The study only included women from Canada, so it’s not clear how well the results generalize to women from other places. The study also relied on computer-generated images to show differences in lordosis. Future studies could use real-life images.
The study, “Sexual Receptivity Signal of Lordosis Posture and Intra-Sexual Competition in Women“, was authored by Farid Pazhoohi, Ray Garza, and Alan Kingstone.