Researchers injected 8 volunteers with lipopolysaccharide (LPS), a molecule found on bacteria that induces a strong “internal” immune response similar to the one that occurs when people are sick (e.g., increases in body temperature and immune cells). The volunteers wore t-shirts to collect their body odor (and also provided t-shirts worn after saline administration, which served as a control condition). A separate group of participants later rated the t-shirts for pleasantness and healthiness. The participants rated the LPS condition t-shirts as more unpleasant and less healthy relative to the ‘normal’ t-shirts. In other words, when we’re sick, we release a funk that tells others to stay away. Follow your nose—it always knows.
Olsson, M. J., Lundström, J. N., Kimball, B. A., Gordon, A. R., et al. (in press). The scent of disease: Human body odor contains an early chemosensory cue of sickness. Psychological Science.