Smelling Good and Bad Love
When it comes to discerning a new hot love, we should trust our noses. That’s the message from new research which shows that amongst the 10,000 different odours we humans can smell, the one that might be most critical to our future is the unconscious one of sniffing out a compatible mate.
Scent not only tells males which females are primed to conceive, but it also lets both sexes sense compatible and incompatible partners.
That’s because scientists are discovering smell helps attract us to partners whose MHC complex (part of a constellation of genes that control the immune system) is most different to our own, increasing our chances of good sexual chemistry and successful reproduction.
Varied MHC receptors not only increase our ability to fight infection, but MHC is also involved in tissue rejection. Conceive a child with a person whose MHC is too similar to your own, and the risk increases that the womb will expel the fetus. Find a partner with sufficiently different MHC, and you’re likelier to carry a baby to term.
The T shirt test
Studies show that laboratory mice can smell too-similar MHC in the urine of other mice and will avoid mating with those individuals. In research at the University of Bern in Switzerland, human females were asked to smell T shirts worn by anonymous males and then pick which ones appealed to them.
Time and again, they chose the ones worn by men with a safely different MHC – except for women who were on the birth control pill. The Pill – which chemically simulates pregnancy – – throws women off the MHC scent, vastly increasing the chances of choosing a “Bad Love” partner. When women discontinue the daily hormone dose, the protective smell mechanism kicks back in.
Risking bad love
Another hormone to mask our ability to detect incompatible MHC is adrenaline. Any overwhelming emotional experience that ratchets up your sensory system can distort your perceptions, persuading you to take a chance on someone you should avoid.
Research shows that people who meet during a crisis–an emergency landing of their airplane, say–may be much more inclined to believe they’ve found the person meant for them.
If that sounds a lot like what happens when people meet and date under the regular influence of drugs or alcohol, only to sober up later and wonder what in the world they were thinking, that’s because in both cases powerful chemistry is running the show. When hormones and natural opioids get activated, psychologist and sex researcher Jim Pfaus of Concordia University in Montreal told Time magazine, you start drawing connections to the person who was present when those good feelings were created. “You think someone made you feel good,” Pfaus says, “but really it’s your brain that made you feel good.”