Women experience greater jealousy when their romantic rivals have highly feminine faces

A study published in Scientific Reports found that heterosexual women report greater jealousy when imagining women with more feminine faces flirting with their romantic partner. This pattern was also present in lesbian participants, though the strength of the association was significantly weaker.

Facial femininity is the degree to which a person’s facial features display traits that are typically associated with female faces. These traits include larger eyes, fuller lips, a smaller jaw and chin, higher eyebrows, and smoother facial contours. Facial femininity is influenced by biological factors such as sex hormones, especially estrogen, during development.

Researchers most often study facial femininity in the context of evolutionary psychology and social perception. In general, women with feminine faces tend to be perceived as more attractive, more youthful, and healthier. Studies have also indicated that facial femininity can influence social judgments—women with highly feminine faces tend to be perceived as warmer, kinder, and more trustworthy.

Study author Junzhi Dong and his colleagues note that evolutionary theory suggests individuals displaying cues of higher “mate value” (e.g., those who are physically more attractive) represent a greater threat to romantic relationships and, consequently, elicit greater jealousy.

While previous studies have shown that feminine rivals trigger higher jealousy, those older studies often relied on computer-manipulated face images and forced-choice tasks. Critics argue this method lacks “ecological validity” because it does not reflect how we view real, unedited people in the real world. With this in mind, the researchers conducted a new study to see if the jealousy effect holds true when women view natural, unmanipulated photographs of potential rivals.

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Study participants included 51 heterosexual women and 49 lesbian women from the U.K., with an average age of 28 to 29 years. They were shown a sequence of 50 natural pictures of white female faces with neutral expressions and asked: “Imagine this person was flirting with your romantic partner (if you do not currently have a romantic partner, imagine that you do have one). How jealous would you be?” The women provided their answers on a 1–7 scale ranging from “not very jealous” to “very jealous.”

To ensure accuracy, the study authors used two different methods to determine how feminine the 50 faces actually were. First, they used statistical software (the facefuns package in R) to map facial landmarks and produce a purely objective, mathematical measure of face-shape femininity. Second, they had a separate group of 30 heterosexual and 30 lesbian women rate the subjective femininity of the faces.

Both measurements yielded the same results: heterosexual women reported significantly greater jealousy when imagining more feminine women flirting with their romantic partner. This same pattern was observed in lesbian women, but the strength of the association was weaker.

The researchers suggest this weaker correlation may reflect the fact that the lesbian dating pool features a wider variety of attractiveness preferences (e.g., the butch/femme dynamic), whereas heterosexual men are more universally drawn to highly feminine female traits, making a feminine rival a more uniform threat to straight women.

“Collectively, these results present further evidence that facial femininity of potential rivals influences women’s reported jealousy, particularly in heterosexual women, and is further evidence for the proposal that putative markers of the mate value of rivals play a role in women’s jealousy,” the study authors concluded.

The study confirms that past findings regarding facial femininity and jealousy were not simply a byproduct of manipulated photos. However, the study does have limitations. It was conducted on a relatively small group of English-speaking women from the U.K., and all 50 photos used in the experiment featured white women. Additionally, bisexual and pansexual women were excluded. The authors note that findings in other cultures, across different sexual orientations, or with more diverse image sets might yield different results.

The paper, “Facial femininity of potential rivals predicts jealousy in both heterosexual and lesbian women,” was authored by Junzhi Dong, Benedict C. Jones, Esperanza Miyake, and Victor K. M. Shiramizu.