"More masculine markers were associated with less-favorable environmental attitudes," researchers report. "Individuals with more masculine faces were more likely to want to use the environment for their own personal gain, and were less likely to want to protect the environment." (Photo: Jakob Owens/Unsplash)

Think of the most ruggedly masculine guy you know—the one with the big jaw and deep voice. Now ask yourself: Where have you spotted him around town?

New research suggests it probably wasn't at your local Sierra Club or Greenpeace chapter.

A Canadian research team reports that men with more masculine facial features tend to be less interested in environmentalism than those who lack such features. Men whose voices are rated as more manly are also less concerned about preserving and protecting the natural world, the team finds.

Their results illustrate, and may help explain, the "robust sex differences in environmentalism," write psychologists Nicholas Landry, Jessica Desrochers, and Steven Arnocky of Ontario's Nipissing University. While women's higher level of green behavior is usually attributed to "cultural influence and the socialization of gender roles," this new research suggests that hormones may play a significant role in environmental attitudes.

The study, in the Journal of Environmental Psychology, featured 162 male Canadian university students. All provided saliva samples so their levels of testosterone and cortisol could be measured. Trained research assistants rated their facial masculinity by measuring the ratio of facial width to height, as well as cheekbone prominence. Other research assistants listened as participants vocalized common vowel sounds, such as "ee" and "ooh," and used pitch along with other variables to rate the subjects' levels of vocal masculinity.

The men also completed a standard survey of environmental attitudes. Using a seven-point scale, they reported their level of agreement or disagreement with 24 statements reflecting either the importance of "protecting and preserving nature," or the belief that nature should be "used and altered for human objectives."

"More masculine markers were associated with less-favorable environmental attitudes," the researchers report. "Individuals with more masculine faces were more likely to want to use the environment for their own personal gain, and were less likely to want to protect the environment. [Those] with more masculine voices were less likely to want to preserve the environment, but were only marginally likely to want to use the environment for human gain."

The results regarding the effects of testosterone and cortisol were less definitive. The researchers found that high testosterone in itself was only linked with anti-environmental attitudes when cortisol (popularly known as the "stress hormone") was also high.

The researchers caution that levels of both of those hormones fluctuate significantly from day to day. Masculine facial features, which have been linked to higher levels of testosterone both in the womb and around the time of puberty, may be a better indication of a man's average testosterone level (or his levels when he was forming his worldview), but more research will be necessary to determine that definitively.

These findings are novel, but not totally unexpected; previous research has linked masculine facial features with higher levels of aggressiveness and lower levels of empathy. Such results could conceivably reflect the fact that, thanks to their perceived handsomeness, such men receive more deferential treatment, which can lead to feelings of entitlement.

But the researchers believe they have found evidence of "biologically driven differences" between men and women when it comes to environmentalism. Perhaps those testosterone-enhancing drugs have a pernicious side effect nobody expected—and one that could hurt us all.