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Human scent as a first-line defense against disease
Amy R Gordon1, Johan N Lundström1,2,3,4, Bruce A Kimball2
1Division of Psychology, Department of Clinical Neuroscience, Karolinska Institutet, Nobels Väg 9, 171 77, Stockholm, Sweden.
Scientific Reports
|October 4, 2023
Summary
When healthy humans experience temporary inflammation, their body odor becomes more unpleasant. This change in scent, detected via olfactory cues, may signal illness and promote avoidance of sick individuals.
Area of Science:
- Immunology
- Human Olfaction
- Behavioral Ecology
Background:
- Body odor differences between sick and healthy individuals are suggested.
- In non-human animals, olfactory cues signal avoidance of sick individuals.
Purpose of the Study:
- To investigate if experimentally activating the innate immune system in healthy humans alters their body odor perception.
- To determine if induced inflammation makes body odor seem more aversive.
Main Methods:
- Healthy participants received an endotoxin (lipopolysaccharide) injection to induce transient systemic inflammation.
- A control group received a saline injection (placebo).
- Body odor samples were collected for behavioral and chemical analyses.
Main Results:
- Individuals with experimentally induced inflammation had body odor perceived as more unpleasant than the placebo group.
- Chemical analysis indicated qualitative, not quantitative, changes in volatile body odor components.
- Odor cues of inflammation were detectable within hours of immune system activation.
Conclusions:
- Experimental activation of the innate immune system alters human body odor, making it more aversive.
- Detectable odor cues of inflammation may serve as an early defense mechanism against pathogen transmission.
- This suggests a biological basis for pathogen avoidance behaviors in humans.
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