Conducted in Sweden, the new research was published this week in the British journal Royal Society Open Science.
It may not be nice to talk about bad breath, stinky feet, sweaty body odor or the smell of feces, urine or intestinal gas, but we pretty much all notice it. Some of us shrug and move on. But some of us feel true moral outrage at the very whiff of it.
And with some good reason. Our sense of smell, after all, is one of our most primitive defenses against the dangers of spoiled food, contagious disease and hazards that might lead to death.
Walk into a cave with the stench of a decomposing body, and the disgust that would make you run away and never return might well allow you to live long and propagate your genes. A more relaxed approach to putrid smells, by contrast, could spell your early demise.
But as humans began to live in social groups, that disgust appears to have proved protective in new and different ways. Dislike of foreign people and their unfamiliar social practices likely protected some early humans from hostile invaders and from pathogens against which they had no immunity.
No surprise, then, that neuroscientists peering into the modern brain at work see little difference between physical revulsion — disgust — and moral indignation, which, as luck would have it, we also call disgust. Whether this powerful human emotion is a response to people or customs we find strange or to smells we find funky, it activates much of the same brain machinery.
And in modern political societies, it makes sense that people who have a preference for order, tradition and familiar people would choose policies and leaders that would tightly control society and harshly punish rule-breakers. People who are more tolerant of chaos, novelty and the occasional whiff of danger or subversion would be drawn to less authoritarian government.
The authors of the new research build on a field of study intent on illuminating the ways in which cognitive styles, personality traits and genetic influences might give rise to certain political leanings.
Researchers in this field have found links between those inclined to disgust sensitivity and "ethnocentrism," or a preference for one's own kind. They've found differences in disgust sensitivity that appear to distinguish American liberals from conservatives. And there's very mixed evidence that people who would describe themselves as conservative in the United States are inclined more than liberals toward negative emotions such as fear and disgust.
The authors of the current research project decided to see if maybe something as primitive as response to odors given off by the human body could be politically revealing. In two separate studies, they used several standardized tests to query study participants about the level of disgust they would feel in response to a dozen scenarios describing body odors and then, about their broad preferences in social and political policies.
As the authors predicted, respondents' high levels of olfactory body odor disgust correlated with their responses on a standardized scale of "right-wing authoritarianism." Respondents who showed high levels of anxiety about contracting disease — germophobia — also tended to rank high in authoritarianism, suggesting again that we use olfactory signals as a warning sign of potential biohazard.
The authors of the study describe the magnitude of the association they found as "small-to-medium size." That's not surprising, they added: There's little disputing that socialization, a process by which parents and surrounding communities impart explicit messages about their values, is most important in shaping political attitudes. But if a drive so deep-seated as our instinct to survive drives our political beliefs even a little bit, the authors suggested, that would be a surprise.
In a third study, the Swedish researchers looked for a link between respondents' levels of body-odor disgust and their support for the two presidential candidates who at the time of the study were leading the polls — Hillary Clinton and Trump. They found a correlation between high ratings on the authoritarian scale and positive attitudes toward Trump.
The effect-size of that link was small, the authors acknowledged. But the relationship between the two — support for Trump and body-odor disgust — "was found to be confidently above zero," they wrote.
Trump has described himself as a "very much of a germophobe."