Single People Smell Different, According to Science

While most of us rely on eye contact and body language to assess relationship status, scientists have found another telltale sign of singleness: smell.

A study by researchers from Australia's Macquarie University and published in the journal Frontiers in Psychology asked 82 heterosexual women to assess the body odors of six male participants. They found that single men were rated as having stronger body odor than those in relationships.

"Stronger body odor might help you stand out more. It might signal dominance," Mehmet Mahmut, one of the study's authors, told Newsweek.

The scientists were unable to conclude exactly why this difference exists, but they do have some theories: "Testosterone is associated with mate-seeking behaviors," Mahmut said. "We know from previous research that higher testosterone is linked to stronger body odor...Potentially single men do have higher levels of testosterone."

The study did not directly test testosterone levels in the participants, but previous studies have found that single men tend to have higher levels of testosterone than men in long-term relationships.

"Men who are in relationships tend to have lower levels of testosterone, but we don't know when that transition occurs...There is no longitudinal research in hormone studies," Mahmut said.

He also pointed out that correlation is not necessarily indicative of causation and the data may have been skewed by certain demographic factors: "Older men are more likely to be partnered and testosterone decreases as you get older."

Mahmut speculated that there might be other reasons for this body odor discrepancy.

"It could just be a social reason," he said. "It's possible having a partner telling you, 'hey, you haven't had a shower in a day' makes you more likely to have less body odor."

There is some evidence that men are more attractive to women when they are in the follicular phase of their menstrual cycle, and their testosterone levels are at their highest. However, the differences are less pronounced.

"Women probably have a better sense of smell and are more interested in the smells around them," Mahmut said. "They also report the smell of a potential partner being more important."

Mahmut hopes that his research will help us better understand the science of human attraction.

"Being attracted to a partner...it's the basis of life," he said. "A basic part of being human is forming connections with other people. A life partner is one of the most important connections you will make."