It's the age-old question and one which psychologists and agony aunts have delved over for decades: what exactly attracts a woman to a man? Is it the colour of his clothes, the length of her arms or even the odd facial scar? According to a wealth of scientific reports on the subject, it's all these things - and many more. Based on a new study that claims men with deeper voices are more desirable to women, we take a look at the factors which claim to influence sex appeal, for both men and women. Find out more - with a little help from the world of celebrity - below...
Turn on: deep voice
According to a new survey from the University of Aberdeen, women find men with lower-pitched voices more memorable. Because humans rely heavily on memory, this trait is thought to have become shaped by evolution - meaning women scan for men with deeper drawls, making them more desirable as potential partners. Good news for those who can emanate the late Barry White...
Turn off: manliness
But bad news for Bruce Willis and his macho wannabes. Another study from the University of Aberdeen found that women in the developed world now prefer more feminine-looking men with full lips and delicate cheek bones - as opposed to a square jaw, low brow and muscles associated with traditional manliness. Researchers concluded that a higher quality of life means women now have to worry less about the strength of their partner and potential offspring, hence the shift.
Turn on: wearing red
Wear red, knock 'em dead - so says a study from the University of Rochester and University of Munich, which found men wearing red are more attractive, desirable and are seen as having a higher status in the eyes of women. The research was based on women rating photos of a model dressed in different coloured polo shirts and framed by different shades. Is that how Orlando Bloom wooed Miranda Kerr, we wonder?
Turn off: being happy
We personally could never resist Will Smith's chirpy smile - but it seems not all women feel the same way. A team of researchers from the University of British Columbia in Canada found women are least attracted to smiling, happy men, instead preferring those who look proud and powerful or moody. Study co-author Alec Beall said, "We did not ask participants if they thought these targets would make a good boyfriend or wife - we wanted their gut reactions on carnal, sexual attraction."
Turn on: scars
A survey published in the journal Personality and Individual Differences found facial scars (such as Rhys Ifans' here) increase women's rating of men's attractiveness in the short-term. Rob Burriss, of Penn State University, said: "A person with scarring might be seen as more brave, daring, or masculine." But there's a catch - the allure only applies to casual flings, rather than long-term relationships.
Turn on: wearing red
As with men, women are apparently more attractive when wearing red (Liz Hurley, take note). Two University of Rochester psychologists found the colour captures men's attention and makes them feel amorous - though they are unaware of the effect. The impact is thought to have evolutionary roots related to the sexual impact of red in nonhuman primates. Female baboons and chimpanzees redden when nearing ovulation, for example.
Turn off: being funny
Men find very funny women such as comedian Miranda Hart a turn-off and are even intimidated by them, a project from three leading American universities claimed. Hundreds of men and women in their twenties were questioned for the survey. "When forced to choose between humour production and humour appreciation in potential partners, women valued humour production, whereas men valued receptivity to their own humour," said Dr Martin at the University of Western Ontario.
Turn on: full lips
A study that tracked the eye movements of 50 men as they were presented with images of different women found lips to be a focal feature. "When the women wore lipstick, the men gazed at their lips for an average of seven seconds – spending just 0.95 seconds looking at their eyes and 0.85 seconds studying their hair,” the Manchester University report said. It concluded that women with fuller lips and/or wearing lipstick are more attractive to men; something that Angelina Jolie could surely have told them.
Turn off: being blonde
Contrary to traditional belief, a recent study from the social network site Badoo concluded that men prefer brown or black hair to blondes. 60% of those polled said they were attracted to darker locks, as opposed to 29.5% who rated blondes. Lloyd Price, from Badoo, said, "I was amazed that blonde hair did not top the list." Not that Sienna Miller has much to worry about though...
Turn on: long arms
Arm length is the most important contributing factor in men rating the attractiveness of women, according to researchers at the University of New South Wales in Sydney. They found women with long arms (say, Heidi Klum) were perceived as more attractive than those with long legs, and that arm length overall was the most significant determinator of beauty among subjects questioned.