Attraction between people has often been described as “chemistry”. This article looks at the role of pheromones in love, relationships, and genetics.

Finding a partner who will provide the best genetic code for your child may be the last thing on your mind right now, but your nose is on that precise mission.

Compared to other animals, our sense of smell is dismal, and research shows that humans can only distinguish up to 10 000 scents. However this excludes the odours we detect subconsciously. Although we do not knowingly sense them, these subliminal aromas can tell us a great deal about members of the opposite sex.

What are pheromones?
Pheromones in animals are understood to be important in stimulating sexual attraction, establishing territories, and enabling social recognition. However, when it comes to human beings, scientists are still trying to understand the role they play in love.

Pheromones are highly individualised chemical signals that can influence sexual attraction and behaviour in others. However, they play a greater role in the survival of the human race.

Humans each have a unique group of genes – known as the Major Histocompatibility Complex (MHC) - that aid the immune system in its war against diseases. MHC molecules are special protein markers that are attached to cells to help the body recognise whether a cell is an invader, such as a bacteria or virus. If a cell is identified as an invader, the body’s immune system launches a defence mechanism to destroy it. Different human beings have different MHC molecules that are good at recognising different invaders. So by choosing a mate whose MHC molecules are different to your own, you are ensuring that your offspring will have a wide variety of MHC molecules that can identify a large array of invaders. Thus, your offspring have a better chance of survival.

Finding Mr/Mrs Right
So how can we tell whether a person is a good mate? Just follow our nose. Research shows that we are sexually attracted to the scent of members of the opposite sex with the least similar genes to our own. For women, the scent of men with similar MHC genes often reminds her of a relative’s odour which will influence her level of sexual attraction to that particular male. Men are also attracted to the scent that identifies peak times of fertility for women. When women ovulate their bodies produce copulins which are scents that attract men. When men smell copulins their testosterone levels rise and they in turn secrete androstenone, which is male sweat after exposure to oxygen. Other than during ovulation, androstenone is usually unattractive to females.

Women and pheromones
Ladies, ever noticed that your period arrives at the same time as your sister’s, work colleagues or the friends you spend a lot of time with? Well, that would be because of pheromones which play a large role in your fertility. While those in laboratories with white coats are still trying to fully understand the significance of this, one thing is sure: if you are a man in an office predominately filled with women, you may have to deal with all the PMSing at once.

Recent research suggests that women on birth control pills often think a man with similar MHC genes smells better. This is possibly because their body is tricked into thinking it is pregnant and the scent of similar MHC genes reminds her of the comforts of home and family. If this is true, women on the pill can assume that their natural preferences are reversed. What makes this so scary is that studies reveal that relationships with partners with similar MHC genes are more likely to have fertility and infidelity problems.

Attraction is not random. It’s a process of natural selection and a subliminal communication between bodies. So pay attention to the scents of others and - in the name of love - sniff as many people as you want.

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