Love at First.. Sniff?

The smelling stimuli we pick up from each other plays a bigger role than we think. By attracting us to our most genetically different and  most compatible partners; it just proves there is a lot to be said for relationship “chemistry”.

We have all heard how pheromones secreted in our sweat can supposedly attract the opposite sex, and certain pheromones have been proven to alter levels of hormones in the recipient smeller. But studies have shown that we produce a different molecule, which rather than causing a hormonal change, plays a significant role in deciding how attractive and compatible you find a person.

The “chemistry” that attracts a lover, friend, or foe is something distinct to each individual and can be traced right down to your genes. It reaches beyond physical traits and personality, to subconsciously influence behaviour. These chemical signals that are in your sweat, tears and saliva are directly influenced by your immune system.

MHC molecules (major histocompatabiliy complexes) are important in identifying invaders in our bodies, such as viruses and bacteria. The range of MHC molecules varies from person to person and the larger the diversity of MHC genes, the better adapted the individual is to fighting off disease. These molecules have been shown to influence a person’s natural odour.

A study into mating preferences in humans by the biologist Claus Wedekind, had six males wear T-shirts for two consecutive nights, the odours of which were then rated by females in degrees of pleasantness. Men with MHC genes that differed most to the females scored much more attractive than those with similar gene ranges. In fact, scents from MHC-dissimilar men actually reminded the women of their current or past mates more than the MHC-similar men, suggesting the subconscious analysis of MHC genes in humans plays a large part in our partner choices. Studies have suggested men are less sensitive to smelling stimuli than women.

The way we respond to chemical signals differs depending on one’s sexual orientation; heterosexual and homosexual women respond differently to male sweat. Smell stimuli can also be a turn off; the scent of female tears has been proven to lower sexual arousal in men. 

 These olfactory signals that encourage mating between those with dissimilar genes is biology’s way of trying to mix up the human gene pool and produce more virile offspring. Parents with more diversity in their MHC genes would have offspring with stronger immune systems, who will therefore be better adapted to fight the pathogens the world throws at them. It also deters inbreeding and close family relations. Evolution has even taken it a step further, to the point that parents with MHC similar genes are more likely to lose a child in the early stages of pregnancy than another couple with MHC similar genes.

An article I wrote last year for QMessenger online.