Each person's immune system influences the natural scent they emit. And the stronger the smell, the more potential partners you tend to attract. Yeah, 'natural scent' sounds an awful lot like a euphemism for body odor (that repels rather than attracts, right?), but there must be something to it because a new study is looking at ways to fabricate that uniquely human scent and add it to bottles of perfume. That way, we'll all have a better chance of finding someone who's an ideal match our specific immune fingerprints, known as "major histocompatibility complexes (MHCs)."
University of California researcher Cristina Davis studies how body odor relates to a person's immune status. Davis says that how we smell could give others clues about long term compatibility, which is important because some people have incompatible immune systems. If that couple procreates, their children could be at an evolutionary disadvantage with "poor defense against invaders or a tendency to attack the body's own cells."
One explaination for the popularity of perfume in general is that a classic chemical in perfume already mimics immune system chemicals:
To find out, the team created synthetic versions of portions of the MHC molecules. Then they had a group of 22 women apply four different versions of a perfume under their arms over two different nights. The consciously detectable smell was identical, but one contained an MHC-like molecule similar to those produced by their own immune system, while the other armpit had a foreign MHC mimic. Women who didn't have colds and didn't smoke consistently preferred to wear the mixtures that "smelled" like their own immune system, suggesting that they were subconsciously broadcasting that trait. "This tells you it is not your free will to decide what kind of perfume you like on yourself, it's dictated by your MHC genes," Milinski said.
It sounds like we're already doing this sort of thing with perfume, at least to some extent. So, if we could all just further "broadcast" our scents with extra help from synthetic immune chemicals, maybe more of us could end up with compatible mates.