Congenital anosmics breathe differently than smellers.

Turns out that people who smell take, as the article puts it, “exploratory sniffs.” The breathing rates between anosmics and smellers are the same, but smellers do like this little mini sniff-like inhale at the end of drawing a breath, and they do this several hundred times per hour.

During sleep or in a controlled odor-free room, the “extra inhalation” patterns even out between the two groups, but additional differences between the breathing patterns of the two groups were significant enough that researchers could tell if a person was a smeller or an anosmic with 85% accuracy just by looking at the breathing patterns.

It’d be interesting to expand upon this study by looking at acquired anosmics, too (this just compared congenital to smellers).