Tuesday, 9 May 2006

Sniffing out a partner

What makes you fancy someone? What is it that you look for in a partner? This week on Mr Science, we will continue our exploration of the science of love, and take a look at how your genes, your nose and even the Internet can all play a role in for whom you fall.

There are some facts that are unavoidable – some people are simply just beautiful. Perhaps they have symmetrical faces – it has been shown that men prefer women who are close to symmetrical. Perhaps their bodies contain the golden ratio, as discussed in previous weeks in the Mathematics of looking Beautiful. In women, men seem to look for full lips and soft facial features. In men, women seem to prefer broad shoulders and the appearance of sexual potency. The desire for these features seems to be conscious and universal.

However, not everyone can end up with the Brad Pitts and Natalie Portmans of this world. It would seem that people fall for those who have similar attractiveness, intelligence and "status" to themselves – that is, those within their league. If everyone fell in love with a movie star, only very few people would end up breeding, and this is obviously bad for evolution.

On the more subconscious level, a set of genes known as the Major Histocompatibility Complex (MHC), seems to play a role in to whom we are attracted. We actually look for people who have a different MHC to ourselves. The MHC helps us fight off pathogens, so the offspring of two people with different MHCs has a broader immune system than the offspring of parents with similar MHCs. And it would seem that our noses sniff out this difference. A 1995 study by Claus Wedekind of the University of Bern discovered that women prefer the smell of sweaty shirts from men who have a distinctly different MHC to themselves. This is similar to the situation with rats, who smell the pheromones in each other’s urine to determine their resistance to disease.

An interest exception to this rule is for women on the contraceptive pill. These women prefer men with a similar MHC to themselves. Women’s preferences also change throughout their menstrual cycle, as during periods of high fertility they prefer men with strong masculine characteristics, whilst at other times, prefer more stable caring men.

Another recent, rather Freudian, finding is that we seem to prefer a partner who reminds us of our parents. Men seem to prefer women who are like their mother, and women want the man of their dreams to remind them of their dad. David Perrett of the University of Scotland performed a computerised study where he morphed pictures of participants’ faces into the faces of others, and discovered that his participants preferred the faces that contained fractions of their own face – even though they could not consciously determine their own faces on the screen. He suggested that this was because these faces remind us of the faces we constantly see during our early childhood – the faces of our parents. It has even been suggested that we prefer someone to smell like our parents. It would seem that we are seeking our partner to possess an immune system which is a blend of the tried and true immune systems of a parents, and that of one that is completely different to our own, to make sure our offspring has a wide range of genes for immunity. We seem to desire a balance between inbreeding and outbreeding.

Not all relationships however are born out of compatible genes and smells. Many modern relationships start in that very modern of media, the Internet. There is growing evidence that the Internet can be more conducive to open relationships than first meeting in reality. This phenomenon has been called the “hyperpersonal” effect by Joe Walther of Cornell University, and refers to the fact that when communicating by typed messages, we have more time to construct our responses and are often more intimate and honest. By not having to look at, or hear the person to whom we are talking, we can focus solely on what we are saying and not the way we look or sound. This allows us to build positive impressions of each other without the visual clues that might have normally put us off. This means we get to know each other from the inside out. Walther also uncovered that, despite its ease, people are less likely to lie online, possibly because there are no uncomfortable consequences.

Another researcher, Katelyn McKenna of Ben Gurion University, thinks that in some cases, an attraction built on the Internet that may not have started in real life, may be strong enough when the couple do finally meet offline. Indeed, McKenna thinks that sometimes starting the relationship in the safe environment of the Internet, where people are more honest and open about themselves, may be preferable. The danger is that, because there is no physical contact, participants in online romance may fill the gaps with what they would like to believe about the other person, and not what is actually the truth.

The road to true love seems to be a mix of the conscious and the unconscious, and may take unexpected turns. Until next week, try and find yourself an object of affection, and next time on Mr Science, will we take a look at how you can best scientifically woo your love.

Listen to this show here


  1. Hooray for internet relationships! Word of caution for first time users, to avoid embarrassing consequences always make sure you type in the right address ;)

  2. I agree! Been going out with my boyfriend for 3 months now, although we spoke online for 2 months before. I can honestly say I'm in love.
    It definitely helped that we concentrated on the content of conversations before we met (we were sending long messages to each other daily), which made the first date just that bit easier. It was a bonus that he's good-looking as well ;)