Gail Sullivan, Washington Post, September 16, 2014

Conservatives and liberals do not smell the same to potential mates. According to a study published this month in the American Journal of Political Science, people can literally sniff out ideology–and this may explain why so many couples share political beliefs. Or, as the study’s title says, “Assortative Mating on Ideology Could Operate Through Olfactory Cues.”

Researchers led by Brown University political scientist Rose McDermott found that, to a small but significant degree, people prefer the body odor of those who vote as they do.

Previous studies showed long-term mates are more similar when it comes to politics than anything else besides religion. {snip}

To test the link between smell and party affiliation, researchers rounded up 146 people aged 18 to 40 from “a large city in the northeast United States.” They used a seven-point scale to determine where they fell on the political spectrum. They sent 21 of these–10 liberals and 11 conservatives–home with fragrance-free soap and shampoo and a gauze pad taped to their armpit. {snip}

They returned the stinky armpit pads 24 hours later. Then 125 participants sniffed the stinky pads, taking a break between whiffs to cleanse their nasal palate with the aroma of peppermint oil. The sniffers, who never saw the people whose smells they were evaluating, then rated the attractiveness of each armpit sample on a 1 to 5 scale.

The subjects found the smell of those more ideologically similar to themselves more attractive than those with opposing views.

“It appears nature stacks the deck to make politically similar partners more attractive to each other in unconscious ways,” the researchers wrote.

Evolution might explain it. “Parental similarity in values increases the likelihood that such individuals may be able to say together long enough to raise their children successfully into adulthood,” the researchers wrote.

{snip}