Even the most debonair men will likely tell you they’ve been tongue-tied around women at some point in their lives. Now a new study suggests that when young men interact with a woman who’s ovulating, they actually alter their speech patterns.

Research with 123 male and five female college students, all of them heterosexual, revealed that when the ladies were fertile, the guys picked up on subtle changes in their skin tone, voice, and scent, and were less likely to mimic their sentence structure — perhaps to highlight the men’s creativity and nonconformity, two qualities believed to attract potential mates.

In these new experiments, when the women were less fertile, men copied their sentence constructions 62 percent of the time — but the rate dropped to just under 50 percent when the women were at peak fertility.

Evolutionary psychologists have long known that males of various species will change their behavior if they’re trying to find or keep a mate. In humans, this can manifest itself in displays of risk-taking, writing a romantic poem, or using bigger words than usual.

“At least a part of the interpersonal dynamic that exists when men and women are getting to know prospective romantic partners is being governed by the biology of a woman’s body and men’s sensitivity to these biological factors,” says Michael Kaschak, PhD, the senior author of the study and an associate professor of psychology at Florida State University, in Tallahassee.

He added that when researchers repeated their experiments with women only, fertility had no discernible impact on sentence structure. “It didn’t show the same effect at all,” Kaschak says. “The effect was specific to men.”

Kaschak and his coauthor suggest their findings, published in PLoS One, will likely be of interest to language researchers, especially those who study so-called “linguistic alignment” in relationships, adding, “A lot of the behavior that we exhibit when we interact with other people happens on an unconscious level.”

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