Scent with love

IN the adverts, the aroma of perfume causes men to fall at women’s feet, and vice versa. It’s far-fetched, but a new book claims we are drawn to people by their smell.

The Science of Love and Betrayal, by Professor Robin Dunbar, says research has shown that smell is determined by the same set of genes, the major histocompatibility complex genes (MHC), as the immune system.

The MHC is our personal chemical signature and if potential partners are close on introduction, it determines whether or not they find each other attractive.

Dr Brian Hughes, senior lecturer of psychology at NUI Galway, isn’t convinced: “The theory is that, because MHC genes have both an immunity and a smell component, evolution has enabled us to find strong immune systems by using our noses, literally,” he says. “In other words, through subtle olfactory cues, we are supposed to find that people with strong immune systems smell nicer than people with weaker immune systems.

“This is all very theoretical and tentative. In reality, it relies on smell cues that are just so subtle it would be difficult to collect good data to even test the theory. And in today’s world, people use so many smelly deodorants and perfumes, it is nearly impossible to actually find out what they really smell like.

“At least it is very difficult to do so before we decide to form a romantic relationship with them.”

Dr Hughes says we shouldn’t be concerned about how our sense of smell will affect our judgement of potential partners. “It is probably safe not to worry about mate selection by smell,” he says. “First of all, these propositions are highly theoretical and might not be borne out by the evidence.

Secondly, the utility of these processes will have diminished with modernity — while they may have helped the species reproduce across evolutionary historical time, we now live in an environment where few people have to worry about the health threats and infections that threatened our prehistoric ancestors.

“On average, the health of the species might be enhanced by the capacity of people to select immune-strong mates. However, any such difference is likely to be tiny, and so to be unnoticeable at the individual level. Whether or not you truly enjoy the smell of your partner, you are both likely to live long and healthy lives in today’s medically well-served and technologically advanced society.”

Professor Walter Kolch, of the Conway Institute (a research centre at UCD), says women have a keener sense of smell and are more likely to make choices based upon it. “People can smell what MHC composition other people have and some studies find that people are attracted to those with different MHCs —and they find this out by smelling what MHC the other person has,” he says.

“Partner choice by smell is mainly done by women, whereas males rely primarily on visual cues. Thus, if you are a female with a low sense of smell you may make grave mistakes in partner choice, whereas men just go for the looks anyway.”