Double-blind Study Suggests Humans Have Olfactory Defense Against Contagious Disease

(Medical Xpress)—A European team of researchers working at Sweden’s Karolinska Institutet has found evidence that suggests that humans have an olfactory defense against contagious diseases. In their paper published in Proceedings of the National Academy of Sciences, the group describes experiments they conducted with volunteers undergoing fMRI scans while viewing photos and sniffing body odor samples from people experiencing induced immune response.

Humans have developed a wide assortment of survival skills over a long evolutionary period, which by most accounts has been quite successful for species survival. One of those survival skills may have gone unnoticed until now, however—the ability to smell sickness in other people so as to avoid them and thus prevent infection. In this new effort, the researchers tested this theory by enlisting the assistance of volunteers to serve in one of two main roles—a person made to appear sick, or as someone attempting to judge the health of another person by either looking at them or by sniffing a sample of their body odor.

The experiments consisted of asking a group of 22 volunteers to allow the researchers to inject them with a type of harmless bacteria that would activate their immune systems. The researchers then obtained body odor samples from each, and photographed their faces Another group was injected with a placebo. A second group of volunteers was then asked to undergo fMRI analysis as they looked at the photographs and sniffed the body odor samples.

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