Your Odor: Unique as Fingerprint

Your body has a signature odor, just as your fingers have unique prints. And that "eau d'you" remains even if you change what you eat, a new study finds.

Mammals such as mice and humans are known to have unique, genetically determined body odors, called odortypes, which act something like olfactory nametags, helping distinguish to individuals from one another, even pick out a mate.

An individual's odortype is determined in part by genes in a genomic region called the major histocompatibility complex (MHC), which plays a role in the immune system and are found in most vertebrates.

Sweat and urine

Odortype information is transmitted through body fluids such as sweat and urine, which contain numerous airborne chemical molecules known as volatile organic compounds (VOCs), many of which give off an odor, as anyone who's been in a gym locker room probably knows.

Meanwhile, the type of food an animal or person eats can influence their body odor; garlic, when consumed in large amounts, is a well-known example.

So researchers at the Monell Chemical Senses Center in Philadelphia looked into the question of whether or not changes in diet could possibly get in the way of one's genetically determined odortype and thus mask aromatic identity.

In behavioral tests, "sensor" mice were trained to use their sense of smell to choose between pairs of test mice that differed in MHC genes, diet or both. Researchers used chemical analyses to examine the array of VOC's in urine of mice having different MHC backgrounds and fed different diets.

The results, detailed in the October 31 issue of the online journal PLoS ONE, indicate that genetically determined odortypes persisted regardless of what the mice ate, even though dietary changes did strongly influence the odor profiles of individual mice. Both the sensor mice and chemical analyses could still detect the underlying odortypes.

Like a fingerprint

"The findings using this animal model support the proposition that body odors provide a consistent 'odorprint' analogous to a fingerprint or DNA sample," said study author Gary Beauchamp, a behavioral biologist at Monell.

"These findings indicate that biologically based odorprints, like fingerprints, could be a reliable way to identify individuals," said lead author Jae Kwak, a Monell chemist. "If this can be shown to be the case for humans, it opens the possibility that devices can be developed to detect individual odorprints in humans."

Beauchamp added that similar methods are being used to look for body odor differences associated with disease. Such research could lead to the development of electronic sensors for early detection and rapid diagnosis of disorders such as skin and lung cancer and certain viral diseases.

• 10 Things You Didn't Know About You
• The Body Quiz: What the Parts Do
• How We Smell