In all of my classes I’ve heard an orchestra of sniffling, coughing, and sneezing all throughout the lectures. With so many sick students stuffed into a classroom it’s the prime location to spread illnesses. Besides the most obvious signs of hacking coughs and sneezing, could it be possible for our bodies to smell sickness on others? This article analyzes recent studies, and comes up with the conclusion that it’s more likely than not.
A study that was conducted at a medical university in Sweden suggested that sickness has the odor of a highly active immune system. They performed an experiment where they had eight individuals give body odor samples. Before one session of sample collections they injected each participant with the endotoxin lipopolysaccharide which activities our immune systems, and in another session they inserted a salt solution that wouldn’t have any affect on the immune system. They collected the tightly fitted sweaty T-shirts and had forty volunteers smell the samples twice in a random order and then rate the smell on the intensity, how pleasant the smell was, and how healthy it smelled.
The results showed that the placebo shirts were listed as having a less intense, more pleasant and much healthier scent than the LPS shirts. The researchers suggested that this could have been a “behavioral adaption” and that this could’ve evolved as “a disease-avoidance mechanism.” I wasn’t particularly surprised by the results myself, but an important question is, we can trust the results on the study?
This experiment wasn’t particularly large-scale, and when it comes down to it the results are relying on anecdotal evidence. Despite this, I believe they did a good job controlling for chance by making the participants smell samples twice in random orders. While they offered strong results, correlation does not always equal causation, but if it does in this case then the results offer some good food for thought. One of mankind’s greatest enemies is diseases: the infections invisible to our eyes that destroy our bodies from the inside. Could this possible ability to smell sickness have evolved as a self-defense mechanism? Perhaps our bodies learned over time how to detect illness to protect us from catching it. Could we possibly smell sickness on others before they begin to feel the effects of their illness?
This evidence doesn’t necessarily suggest we should smell everyone to see if their sick or not, or that we should avoid smelly people because we might get ill. However, if you think the sick person next to you in class smells strange, this could be a clue as to why.