Women can pick up cues about how men feel about children from their faces and use the subtle signs to rate them as potential partners, scientists said on Wednesday.

The team of researchers from the United States showed that an affinity for children and male hormone levels play a role in determining how attractive men are to women.

“Our data suggest that men’s interest in children predicts their long-term mate attractiveness even after we account for how physically attractive the women rated the men,” said James Roney of the University of California, Santa Barbara.

In the study of nearly 70 men and women, an interest in children was linked to long-term partnership potential while women were attracted to men with higher testosterone levels as short-term romantic mates.

“The study provides the first direct evidence that women’s attractiveness judgments specifically track both men’s affinity for children and men’s hormone concentrations,” said Dario Maestripieri of the University of Chicago, and a co-author of the study.

The scientists tested the testosterone levels of 39 male undergraduate students from saliva samples. They also determined their affinity for children by asking them to choose between photos of an adult or a baby and to rate their interest.

The researchers photographed the men and showed the photos to 29 female students who were asked to rate the men on whether they thought they liked children, their masculinity, physical attractiveness and potential as short and long-term partners.

The findings, published online by the journal Proceedings of the Royal Society B: Biological Sciences, showed the women were able to choose the men who had expressed an interest in children during the photo test. They also described men who had high testosterone levels as being masculine.