Anneke Meyer wonders if there is an objective answer to the question that moves many men and women’s minds.

Have you ever met up with a couple of friends to go out on a Friday night but one of them keeps changing outfits for ages, asking “red or black high heels? I want to look really sexy, you know?”
“Do I know?” I started to wonder over one of these heated debates about sex-appeal. For the sake of not missing another party, let’s try to find an objective answer to the question of what causes physical attraction between sexes, or rather: “What is sexy anyway?”

If we put together what researchers have found out about sexiness it seems that it’s mostly in the hormones. Researchers at the University of St. Andrews have shown that a man’s attraction to women is affected by changes in his levels of sex-hormones: his attraction increases when his testosterone level rises ¹. But what influences the rise and fall of testosterone levels? Here men go round in circles. What really boosts testosterone levels are sexual stimuli, such as the scent of a woman. Her smell is particularly enticing to him when she is in the fertile phase of her menstrual cycle and thus producing lots of the ovulation hormone, estradiol. Clearly Mother Nature thought about reproduction when she introduced sex appeal.

Men and women may often clash but it seems that, at least in hormone-regulated attraction, there is perfect harmony between genders. Both men and women rate each other as more attractive when the women’s level of estradiol is high ². Still, she is not entirely at the mercy of her hormones as she also relies on his hidden virtues. The very same man is perceived as more attractive when his testosterone level is high. As we know from many animal studies, body-scent tells us lots about hormone levels. So if women identify a man brimming with testosterone as attractive, by sniffing his shirt, this wouldn’t be surprising. Interestingly, a recent study showed that human females do not necessarily need to smell a fellow in order to judge his sexual fitness. Vision alone does the job: women can apparently tell the hormonal condition of a man by looking at his face.

While testosterone seems to be the key to what makes a man sexy this alone is not enough to create long lasting attraction. In order to be desirable as a proper boyfriend or even a husband, men have to possess some aspects of a ‘safe choice’. Here the tide turns against lads who just look too macho. Faces with over-expressed male features, like strong jawbones, are associated with negative attributes such as coldness and dishonesty ³. The true man of her dreams needs a little soft spot, such as fatherly feelings. This is at least, what we learn from the following study. Women were asked to rate men’s attractiveness from nothing but portrait photos. As they were to judge only from pictures, women didn’t have any information about how fond these men were about children. Never the less, men who liked kids were rated as more attractive. Isn’t it amazing how much unconscious information may be gained from a man’s face?

We see, testosterone is not what gives a man appeal, but it is the secret to his ‘sex’ appeal. In some sense the same is true for women because, contrary to popular perception, it is not men alone who produce this potent hormone. Women possess this sex-hormone as well and, just like men, raising their testosterone level turns them on. Those lucky women with baseline levels of testosterone ranging at the upper end of the ‘norm-scale’ are more easily sexually aroused. In fact, for a woman to increase her short term testosterone level, all it takes is merely to think about sex ⁴. Surprisingly, men face more difficulties; in order to raise their testosterone levels they depend on real perceptions. They need to see, hear, look or feel in order to ‘get going’.

So, to summarise these scientific findings, as regards the question “what is sexy anyway?”, it turns out like this: men are sexy if they produce a decent amount of testosterone, which they do whenever they are sexually stimulated. So in order to be sexy men should have sex at least every now and then. Women do seem to have it a little easier when it comes to being perceived as sexy by men. They just have to be women and perhaps think about sex once in a while in order to get more out of it for themselves. It seems that science has come to the rescue of my next Friday night out: it’s not really the heels that matter.

1.  Welling LL, Jones BC, DeBruine LM, Smith FG, Feinberg DR, Little AC, Al-Dujaili EA. Men report stronger attraction to femininity in women’s faces when their testosterone levels are high. HormBehav. 2008 Nov;54(5):703-8.
2. Roney JR, Simmons ZL. Women’s estradiol predicts preference for facial cues of men’s testosteroneHormBehav. 2008 Jan;53(1):14-9
3. Perrett DI, Lee KJ, Penton-Voak I, Rowland D, Yoshikawa S, Burt DM, Henzi SP, Castles DL, Akamatsu S. Effects of sexual dimorphism on facial attractiveness Nature. 1998 Aug 27;394(6696):884-7.
4. Goldey KL, van Anders SM. Sexy thoughts: effects of sexual cognitions on testosterone, cortisol, and arousal in women. HormBehav. 2011 May;59(5):754-64. Epub 2010 Dec 24.