The real reasons we fancy someone

Scientific studies have long suggested we tend to be attracted to people with faces similar to our own, as seen with actors Brad Pitt and Jennifer Aniston. However, according to Dr Tony Little, of the School of Biological Sciences at Liverpool University, we are often attracted to people who look like our opposite-sex parent. Women tend to choose men with the same hair and eye colour as their fathers, while men tend to prefer women with their mother’s colouring.

You might think that hitting on someone who looks like you would be counter-intuitive,

but it may be beneficial. "If we have children with someone very different from us, the children will share 50 per cent of our own genes," says Little. "But if we have a similar partner with whom we share some genes, that percentage will increase." This makes sense, according to evolutionary theories, which suggest our instinct is to promote our own genes: people who resemble us are more likely to be more closely related to us than those who don’t, so reproducing with them could give our children a greater share of "our" genes. Considering the huge amount of time, energy and money we invest in our youngsters, this is hardly illogical.

But it’s not just a question of how we view a potential mate - how we view ourselves also seems to affect the type of face we choose. Research has found that attractive people are more likely to choose potential partners with faces which indicate high genetic benefits.

Little, along with Professor David Perrett, of St Andrews University psychology department, developed this theory using computer-generated images. Researchers created composites using photos of different men’s faces to produce an "average" face. They then created altered images which were incrementally more feminine or masculine by adjusting such details as the heaviness of brows.

When asked to choose which version they liked best, most women preferred the slightly feminised version. The exceptions were women who rated themselves as particularly attractive, who preferred faces at the more masculine end of the spectrum.

What does this indicate? It turns out the reasons for attraction to particular facial types are more than skin deep. A person’s face type can give us clues as to how they might behave. A masculine face is linked to a high testosterone level, which can be associated with great drive - but also a higher likelihood of philandering and creating aggravation in a relationship. Also, testosterone can be damaging to the immune system but if a male can withstand high levels of it, he is demonstrating high genetic quality that can be passed on to his children.

According to the research, women who see themselves as a cut above are more likely to go for macho guys, thereby selecting genetic benefits for their children. Perhaps they think they are so desirable they will be able to keep their man? Most women, however choose to take their chances with more reliable looking types.

Perrett and Little’s latest study reveals something similar going on with men. Those who regard themselves as a bit of a "catch" express preferences for particularly feminine female faces: a small nose and chin, full lips, big eyes are indicators of oestrogen and fertility, explains Perrett. Attractive men make unconscious choices based on the woman’s ability to help transfer their genes to future generations. "A man who has a lot to offer can demand a lot," adds Perrett.

Of course, it may be that all men are attracted to these feminine features - but those with less to offer in the reproductive race are just being realistic about their own possibilities. "It could be beneficial to choose someone of equivalent attractiveness to avoid the costs of desertion," says Little. Maybe ugly men must take what they can get - unless they have something else to offer, of course, such as money or power.

Men’s preferences for female faces are also driven by how they rate their own dominance. Robert Burriss, of the school of biological sciences at Liverpool University, asked men to study pictures of fictitious couples, rating both the man’s dominance in relation to himself and the woman’s attractiveness. The women were judged to be more attractive when with a dominant man over a subordinate man, regardless of her independent ratings.

The significance of biology in choosing is further highlighted by changes that happen to women when ovulating. Research by Dr Craig Roberts, also at Liverpool University, has evidence that women’s faces become more attractive during this time. Precisely how they alter is not yet known, although possible cues include variation in lip colour and size and pupillary dilation. "These are very subtle," says Roberts, "but they could mean that more men will be interested at the very time of the cycle when the chances of conception are highest."

THE TYPE OF relationship you are seeking is also likely to affect your taste. "Women are more interested in a caring, reliable-looking partner for a long-term relationship," says Little. Conversely, those seeking a quick fling are more likely to go for a more masculine-looking man.

It seems women face a serious, although perhaps unconscious, choice: whether to go for a sexy beast of a man who will provide good genes for the kids, or a sensitive, caring guy who will help look after them. Is it any wonder that increasing numbers are choosing to stay single and not make the decision at all?

To participate in online facial attractiveness experiments, check out www.alittlelab.com