Ever wonder why a perfume (or cologne) smells better on somebody else than on you? The reason lies in the interactions of our brains, immune system and nose. Our brains literally know exactly what we smell like and can set preferences based on that for associations with others (particularly sexual partners).
Thomas Boehm, a biologist at the Max Planck Institute of Immunobiology and Epigenetics in Freiburg, Germany, found that a large molecule called the major histocompability complex (MHC), which plays a role in directing immune responses to invading microbes and helps animals choose mates, also can allow us to differentiate ourselves from other people, solely by sense of smell. The research appears in the January 22 Proceedings of the Royal Society B.
In addition, Boehm and his colleagues identified a region of the brain that is activated only by proteins that closely resemble a person’s own MHC molecules.
The researchers had 22 women apply two different MHC solutions to their armpits—one with a solution most resembling their own, the other from another person’s MHC. Overall, women preferred the scent with their own MHC proteins. The brain studies illustrated that this preference wasn’t just for the smell of the MHC, but for the brain to make a distinction between self and non-self.
This link between smell, immune responses and the brain has implications beyond choosing perfume. Now, we know that our sexual selections can be (and probably are) based on the same scent-detection that dogs, reptiles and even fish possess. While we lost the organ those animals use to sniff out mates many evolutionary eons ago, our nose still, um, knows.
Manfred Milinski, Ilona Croy, Thomas Hummel, & and Thomas Boehm (2013). Major histocompatibility complex peptide ligands as olfactory cues in human body odour assessment Proc. R. Soc. B., 280 (20122889) : 10.1098/rspb.2012.2889
attraction, smells, perfume and attraction