The smell of sex: are our noses connected to our desires?

Vision gets all the attention when we think about the way senses relate to human attraction. Makes sense: there are a tonne of visual markers, which may exist for evolutionary, biological or cultural reasons, that influence how and why we’re attracted to other people. But what of the other senses? Smell (or ‘olfaction’, to give its scientific name) is an interesting example as it’s associated with the limbic system – an area of the brain that deals with emotion and memory. Because smell bypasses the higher brain functions that vision and hearing require, it can affect the way we respond to stimulus in some pretty powerful ways. Which made us want to investigate the ways it influences sex and sexuality. Here’s what we uncovered.

Phero what?

You’ve probably heard the term ‘pheromones’. Relative to how long humans have been studying animal biology, it’s a recent concept. The name was coined in 1959 to describe the chemicals that animals excrete that influence social behaviours in the same species, and pheromones’ relation to human sexuality became a source of interest soon after. So is there a magical pheromone that can attract people to you? In short: no. Humans lack a ‘vomeronasal organ’, the biological equipment some animals use to detect and respond to pheromones. However, there’s some evidence suggesting a male-associated pheromone called ‘androstadienone’ can have a positive effect on the mood of women, thus making them more open to sexual response – but studies have been inconclusive to this point.

Getting hormonal.

It’s well understood that the hormone testosterone has a powerful effect on male sexual arousal. For this reason, it’s been theorised that levels of testosterone in men may increase when their partner is ovulating. The idea is that olfactory cues generated by women while they’re ovulating increase levels of the hormone in men and, accordingly, their levels of arousal. This boosts the likelihood of intercourse and, thus, raises the probability of conception. As logical as that may seem, researchers in a Swedish study could not find any evidence for this being a group phenomenon – though it was detected in a small number of individual cases.

Subtle signals.

However, there is a particularly racy study that may contradict these findings. Using data reported by dancers, researchers concluded that the dancers made more money in tips when they were ovulating than in any other part of their cycle. Furthermore, women who were taking oral contraceptives and didn’t experience ovulation didn’t experience a similar peak. So have we finally found evidence of human pheromones having a definitive influence on human sexual response? Sadly, no. The effect could just as easily be explained by the women manifesting subconscious behavioural changes designed to attract a partner at the point she is most fertile.

Is anyone else thirsty?

There is another, equally unconventional, study that might point towards fertility pheromones changing human behaviour – even if that change is small. Researchers observed that alcohol use has a strong correlation with sexual activity. Knowing this, they set up a test to see if unknowing male subjects would drink more beer while alone in a room after sniffing a t-shirt worn by an ovulating women, compared with one worn by a control. Turns out, they did. What’s even more intriguing is that the researchers left a woman’s sweater, purse and clipboard on one of five seats in the room. Men who had sniffed a t-shirt worn by an ovulating woman sat closer to this ‘phantom female’ than those who had not – indicating they were more likely to make sexual approaches.

But what if you can’t smell at all?

Studies have reported that isolated congenital anosmia (read: having no sense of smell at all) has an observable effect on people’s sex lives. Interestingly, these effects vary with gender. For males, the condition was observed to reduce the average number of sex partners, whereas females reported lower levels of security in their romantic relationships. Does this mean – because the subjects couldn’t smell them – that pheromones have a substantial influence on our sex lives? The studies are far too inconclusive to say. These behavioural differences could equally be explained by social insecurity generated by missing this powerful sense.