Scent is the sexiest sense. The ghost that strings the air between two strangers and pulls them in for the kiss. Scent is the sense that runs without the mind – that slides mindless, raw, primal, relentless. Words fail scent. It swims in your subconscious. It is everything you do not know you want. That you cannot describe.
Cannot deny. Scent is the vertigo in every affair. The siren under the cliff. The silent, roaring voices at its edge. It is unknowable, fleeting. So tied up with our unconscious, animal selves that we keep it under wraps. We sanitize our scents more than any of our other sexual signals.
All that scrubbing and rinsing and showering – our mass obsession with laundry and the laundering of our skin. An act of denial. A full-body veil. Why are we ashamed to smell ourselves? What are we afraid of?
We are more guided by smell than we care to admit. When two dogs meet, they both dive for the perineum. When humans meet, they kiss, or hug, or shake hands, but these, too, are actions focused around our most accessible concentrations of scent glands – on our hands, fa-ces and ears.1 We may walk upright, but just like dogs, sniffing is second nature. What’s more, we ape monkeys. Capuchins regularly rub urine into their feet to attract mates. In the pursuit of love, antelopes piss on their own throats and vultures defecate over their toes. Behold, the original eau de toilette. It may be cheap, but it’s not so different from Chanel No. 5.
Your sense of smell is crippled by both nature and neglect. A human nose has only one-twenty-third of the olfactory receptor cells found in a dog’s snout, and two in three of our 1,000 genes for those cells are non-functional, but it’s still a formidable organ that plays a major role in some human societies. The Onge tribe of the Andaman Islands, for example, are highly attuned to odor, which they consider to be the source of a person’s personality.
D. Michael Stoddart, author of The Scented Ape, points out that humans carry more odor- producing zones on their bodies than any other primate. These are our apocrine glands, and they’re the bases from which we project odors out into the social world. Human scents are in urine, semen, vaginal secretions, breast milk, saliva, breath, and, most importantly, in our sweat. The skin carries three kinds of glands: sebaceous, eccrine and apocrine. All your body’s orifices are shrouded with sebaceous glands. They’re on your face, your forehead, eyelids, ears, lips, nostrils and nipples. They can cause acne, but most of the time they release a kind of oil to keep your skin hygienic, soft and waterproof.
Eccrine glands, meanwhile, release sweat. Unless you’re unwell, sweat does not smell. It’s just water and salt. And so to the third gland group, the apocrine glands. In many animals, apocrine glands are used to regulate temperature, like eccrine glands, but in humans, they have no such function. A dog’s biggest, densest collections of apocrine glands are in two anal sacs. Ours are on our hands, cheeks, scalp, breast areolas – anywhere that we have hair. Most primates have concentrations of apocrine glands on their chests. Humans, gorillas and chimpanzees have clusters of them stashed in their armpits. Men have more than women. East Asians have significantly fewer apocrine glands, and men of sub-Saharan African ancestry have the largest and most active variants.
When we’re anxious, excited or aroused, axillary secretions from the apocrine glands flood into our hair follicles. Despite being the source of your personal smell signature, the secretions of apocrine glands – like sweat, or the products of sebaceous glands – have almost no odor whatsoever. Dr. S. Craig Roberts at the University of Stirling explains:
‘Body odor is at least to some extent genetic. Identical twins smell very similar, more so than non-identical twins, who are more similar than unrelated individuals. But bacteria are centrally involved, too – they metabolize protein by-products at the skin’s surface into smaller molecules, volatile compounds, that we can detect through smell. Without them, there is no odor.’
The microflora, the blend of bacterial nations spread out over your skin, are distinct to you and you alone. ‘Don’t mistake this for an entirely environmental effect,’ Roberts continues. ‘They must be either metabolizing genetically characteristic products (e.g. proteins produced by immune system genes, these genes being sufficiently diverse to allow individual differences to emerge) or else these same genes regulate the bacterial microflora on the skin, so people have individually distinct (genetically determined) populations of microflora. Either way, the genes act on the odor via the microflora.’ And while you may try to hide it, your body is trying to spread this smell around. By feeding these bacteria around hair follicles, your body uses the hairs themselves to waft and project your personal odor avatar into the social world.
There’s a sexiness to this smell, the result of steroids released by your body into the hair. There are far more of these in male sweat than female sweat. One of them, androstadienone, has been found to improve women’s mood and heighten their focus – both regarded as important sexual prerequisites. Another, androsterone, is related to musk extract and smells fiercely unpleasant. It is, however, a smell that only women can detect – men lose their ability to detect it from puberty, the same time that hair begins to sprout on their zones of apocrine glands.2
In the animal world, similar releases of steroids from apocrine glands are discussed as pheromones – a chemical signal that changes the behavior of another creature of the same species. In the context of sex, these are the ultimate aphrodisiacs – substances so potent that one sniff of it creates an insatiable desire to mate. In the animal world, they exist.3 Boars express the steroid androstenone through their sweat, and a sow in its estrus period, catching a whiff of it, unthinkingly enters ‘lordosis’, the classic mammalian mating position: face down, back dipped, ass up.4
Man sweat has nothing like that effect, but both men and women appear to use their smell signature to communicate information about their immunity. Your ‘MHC profile’ tells a potential mate whether the genetic make-up of your immune system is too different from theirs to produce healthy offspring – or, more worryingly, too similar, suggesting you might be related. Every version of every MHC gene has a unique scented protein that gets expressed through sweat and ‘activated’ by the skin bacteria.
In a study carried out with ovulating women, whose sense of smell is temporarily enhanced, subjects were presented with a series of men’s used T-shirts, which they had to assess for attractiveness. The women preferred the men whose MHC profiles most varied from their own (gay men prefer the smell of other gay men to those of women and straight men, and there was a similar, if weaker correlation among lesbians). Men with similar MHC profiles to the women taking a noseful of their T-shirts were said to smell like the women’s fathers and brothers.5 A man smell that one woman finds impossibly compelling can be boring, even repellent, to another woman, depending on their genetic compatibility. Swiss researchers have even found that this preference is reversed in women taking oral contraceptives. A lot is at stake – couples struggling to conceive share significantly more of their MHC than more fertile couples.
Let’s get back to that monkey. He’s pissed on his hands, and he’s sitting on the floor, gently rubbing the pungent liquid into his feet in an act that utterly baffled researchers (did it improve his grip on tree branches?) until it was demystified by a study in the 2011 American Journal of Primatology. Humans are capable of equally bizarre behavior when it comes to advertising their smells – women in Elizabethan England were known to pop slices of apple into their exceptionally unclean armpits, before offering the fruity fruit to suitors as a keepsake. Vulva, a perfume launched in Germany in 2011, offers customers the chance to smell like ‘the natural vaginal scent produced by movement and sweating in the female intimate area, the scent that arises a couple of hours after having had the last intensive shower.’ Replicating your own underarm odor, dousing yourself in synthetic vaginal fluids – what makes these actions stranger than paying €80 for a spray mixed up with mucus from an agitated cat’s anus?
Thorsten Biehl runs a perfume boutique in Berlin, selling specialist scents created by well-regarded perfume designers such as Geza Schön and Mark Buxton. In his office – part-lab, part-gallery – he explains the fundamentals of perfume making. ‘There are around 20,000 known raw materials for a perfume, but perfume designers work with a palette of about 2,000 distinct smells. Fifty of those might go into a typical perfume. We measure perfume in terms of one kilo: so one gram per kilo of an ingredient, for example, is quite subtle. Ten grams, you really notice.’ Each perfume consists of top notes, heart notes and base notes. ‘Think of cutting a lime for Cuba Libre,’ says Biehl. ‘The smell fills your whole kitchen, but it’s very reactive, so it’s gone in ten to fifteen minutes. This is the normal duration of the top note. The heart note is a smell that will last for three, four, five, six hours, and the base note is the smell that will stay with you overnight – it might last for days.’
The beast is in the base notes. This is where perfume designers use animal extracts, typically musk, civetone (from civet cats) and castoreum (from beavers). ‘There’s a certain body smell,’ says Biehl. ‘Animalic – some people call it sensual, and most people can relate to it. Some people are repelled because it’s so strong.’ He offers me a small bottle of civetone. I sniff and feel like I’ve stumbled into a foxhole. The smell is sharp, hard, and rude. It reeks of feces ground into a cat-lover’s soft furnishings. But it’s oddly easy to grasp its appeal – it’s demanding and fierce, with an urgency that makes lesser scents seem weak. Crucially, it is just different enough from normal feces to smell exotic rather than incontinent. It’s a fine line.
I ask Biehl if these animalic base notes have something pheromonal about them that makes them core to creating sexual perfumes. He greets my question with polite bemusement. He does enjoy reading about associations, he says, and gives the example of vanilla fragrance, which is thought to echo vanilla notes in breast milk, and therefore to communicate a sense of warmth and security. Similarly, the scent of lemon has been shown to significantly increase people’s perception of their own health, and lavender incense makes people worse at mathematics. But, he explains, the real, historical purposes of using musk, civetone and castoreum is because they are ‘fixative’ – they’re naturally very persistent smells, which, when combined with more volatile, fast-dissipating fragrances, are able to make them last longer.
In any case, these days real musk (a word derived from the Sanskrit for ‘testicle’) or civetone is hard to find, and synthetic alternatives are almost always used instead. In pursuit of the glands lying between the fanged musk deer’s bollocks and bellybutton, humans almost hunted the creatures to extinction. The last of them were saved by the accidental discovery of synthetic musk in the nineteenth century by Albert Baur, a chemist trying to make TNT. In a peculiar discovery over a century later, synthetic civet scent used in Calvin Klein’s Obsession for Men was found to attract tigers, cheetah and jaguars at New York’s Bronx Zoo. The scent’s designer, Ann Gottlieb, told the Wall Street Journal in 2010 that the scent is ‘a combination of this lickable vanilla heart married to this fresh green top note – it creates tension.’
Is there any sexual chemistry, then, behind the way we choose to smell, or is it solely about standing out from the crowd? ‘We are still at an early stage in trying to work out how different fragrances work on different people,’ says Dr. Roberts. ‘We do know that our personal odor suits certain fragrances better than others. In one of my previous studies, led by Jan Havlícek at Charles University in Prague,6 people’s odor blended with their preferred fragrance was rated as more pleasant than their odor blended with another one chosen beforehand by the experimenter. This suggests that people’s preferred fragrances complement their own odor – we appear to do this without realizing it.’
Odette Toilette, a London-based ‘purveyor of olfactory adventures,’ is resolutely unconvinced. ‘I don’t personally buy that. At the very least, it’s bundled up with our cultural use of scent. Do young girls buy whatever scent because it works with their body chemistry or because they’re obsessed with One Direction and they want to smell like them? Does a woman buy Coco Mademoiselle because it works with her body chemistry or because her best mate wore it and she wants to copy her? It’s very difficult to separate out these motivations.’ Her forthcoming book is a cultural and social history of the twentieth century seen through scent. ‘I tend to look at the cultural meaning and collective understanding behind a facet of the smell and why we have those associations. Why does everyone, when they smell a violety perfume, talk about their grandmother? Grannies in fifty years will probably smell like Angel and Coco Mademoiselle. It’s always unstable. People want to know: does it smell fresh and contemporary and sexy and young, or does it smell like a crone? And that’s purely based on what smells are retro because they’re based on a style that was common in the sixties, and all the women who were young in the sixties now look old.’ Sex is social. Perhaps humans have come so far from sniffing each other’s anal scent sacs that the relative compatibility of our immune systems is only one of many factors that fly through the subconscious before we jump into bed. Perhaps it’s even less important than sensing that someone is smart, or kind, or has good taste, or doesn’t smell like an old lady. ‘There’s something very tantalizing about this story that you’re in thrall to your primitive mind and your animal heritage as a human, and your conscious mind isn’t in control of your behavior,’ says Odette. ‘The scientific community is trying to clear away all this cultural baggage and get to the essence of animal behavior, but you can’t get rid of the cultural stuff.’
1. Barbara Sommerville and David Gee of the University of Leeds.
3. Apocrine glands have other uses, too. Skunks use them to release their distinctive defense mechanism.
4. Signoret and du Mesnil du Buisson 1961.
5. Thailand’s Mahidol University has developed an electronic nose that can recognize people by their smell signature by analyzing the bacteria on their skin.
6. Lenochova P., Vohnoutova P., Kubena A., Roberts S.C., Oberzaucher E., Grammer K., Havlícek J. 2012.
Psychology of fragrance use: perception of individual odor and perfume blends reveals a mechanism for idiosyncratic effects on fragrance choice. PLoS One 7, e33810.