What do fleshy tuberose, cooked Brussel sprouts, chocolate, the musk of human sex, faeces, and a decomposing body all have in common?

Indole, dirty, sexy, carnal Indole. You have smelled it thousands of times without knowing its name, but if you are smelling something a little bit overripe, heavy, and with a strange sweetness, it is most likely Indole. Even untrained noses can pull out the waft of clammy decay in a magnolia blossom, the crotch-like quality to heady jasmine or the slightest smell of poop in roses. That is Indole.

Indole is the smell of human bodies and human intimacy, but also an earthly connection between those bodies and the world around them. After all, flowers are the reproductive organs of plants, living, reproducing, and dying, so of course, we would be attracted and intrigued by our similarities to the chemical composition of these glorious flowers.

A philosophical battle over smell has been raging for centuries. The Ascetics (Freud, Weber, Parson, etc.) want to create a sterile anosmic world where people are completely divorced from the reality of their earthly and animal natures, with the hope that, along with the stench, mankind’s baser qualities will go too.

The Sensualists (Bonnot de Condillac, Hume, Locke, most Humanists, etc.) follow that nothing can be known that is not first sensed, so while hygiene is important, we should not be afraid to experience the mere odour of our animal natures or our connection with the natural world. In fact, if we are honest, we really like it.

One of the major battlegrounds for this fight has been perfume, more specifically the scent of women. In the language of flowers that has pervaded European perfumery for centuries, the good girl wore violets, sweet virginal violets that leave the barest trace. The prostitute wore jasmine that had sillage for days. The good girl had to hide her humanness and sexuality for decorum’s sake behind sugary sweetness. Meanwhile, the prostitute, both exiled and liberated from the tyranny of respectability, was free to broadcast both her sexuality and humanity in her choice of perfume.

It wasn’t until the rebellious Flappers of the 1920s, and their racy new fragrances like Chanel No.5, that those smutty indolic florals were redefined.  However, even today in the English-speaking world the clarified non-scent of white musk (think laundry detergent and dryer sheets) rules supreme. While French perfumes like A La Nuit by Serge Luten and Secretions Magnifiques by Etat Libre d’Orange show that something far more human, sensual, dirty, and sexy is on the minds of our French counterparts. So what is Indole?

Smelly Chemistry

Indole’s name is a portmanteau of indigo and oleum given because Indole was first isolated by a treatment of indigo dye with oleum. It is an aromatic organic compound that is found in a wide variety of natural settings including cruciferous vegetables, many flowering plants, the human body, and bacteria.

It’s Indole produced by gut bacteria, along with its smelly bandmates putrescine (hot garbage, bad breath, and vaginosis) and cadaverine (urine and rotting meat), that are the headliners in the miasmic, thick, slightly lemony, overripe scent of decomposition. Putrescine and cadaverine are diamines produced by the breakdown of amino acids such as lysine and are thought to be responsible for the nauseating aspect of decomp. Indole is created by the breakdown of the amino acid tryptophan.

Many people that have smelt a decomposing body will note something that smells like cheap perfume or sickly sweetness. That is Indole’s contribution to this foul accord.  In high concentrations, Indole, and especially its relative Skatole (poop smell), are intensely faecal. Isolated in a lab setting, Indole can resemble the scent of mothballs, but unless you are a chemist or a perfumer you won’t smell Indole in either of these states at high concentrations. So don’t worry about mothball being the next big thing in perfume. If that isn’t enough reason to hate Indole, it is Indole that regulates various aspects of bacterial physiology such as drug resistance and virulence.

Before you get your pitchforks out for Indole, though, keep in mind that it’s derived from tryptophan, which is a precursor of the neurotransmitters serotonin and melatonin.  You like being happy and going to sleep right? Well, Indole is part of that process.

It is also produced by the natural flora of our skin and is especially concentrated in the groin. During sex, the added heat and moisture cause a release of this aromatic chemical. Hence the long association between Indole and sexy. In low concentrations, Indole has a deep ripe floral scent. Our attraction to heavy Indole florals may be more than just a subliminal recognition of our body scents. Studies at the University of Tokyo have shown, that the scent of concentrated jasmine can have a positive effect on mood and brain chemistry, even when the subjects didn’t know what the scent was, or they were told it was something else (helping to show that it was the scent itself and not emotional memories triggered by the scent). More research is needed to state these findings as fact, but the initial research is very compelling.

Why put it in perfume?

Well, the simple answer is it was always there. Indole is part of the aromatic components that make it through extraction in many of the flowers we think of as “sexy,” orange blossom, tuberose, rose, jasmine, and magnolia, just to name a few.

Indole can be isolated and removed in chemical processing, but it takes something away from the result. It’s taking a beautiful woman and turning her to stone. All the form and figure is still there but the warmth, complexity, life and, therefore, death, is gone. Without that, there is nothing compelling about these scents. They become sharp and headache-inducing. Like a Flemish still-life painting if you want a realistic and beautiful depiction of life there needs to be a little bit of rot there too.

As mentioned above our sensualist French cousins have no problem embracing what Debre Ollivier called “the brevity of time and the immediacy of pleasure” in their lives and their perfume. Part of the allure of the classic French florals are their intoxicating indolic notes. Indole in perfumery can make things a little complex, a little dirty, a little risqué, but if I have to choose between smelling like a puritanical washing machine or an oversexed French woman, I’m picking the French woman.

Some Indolic Scents

Just a few ideas to explore your inner sensualist

1. Viva La Mort by Tokyo Milk Tuberose, jasmine, hibiscus, and cardamon
2.  Jasmine and Tuberose by Henri Bendel Straightforward rose, jasmine and tuberose
3. Sepia by Aftelier Blood Cedarwood, lotus, jasmine grandiflorum, tobacco flower, oud, ambergris, and labdanum
4. Tuberosa by Miller Harris Tuberose with a creamy lactonic base of musks, ambrette seed, and benzoin
5. Carnal Flower by Fredric Malle a floral that is fresh, camphorus, spicy, and milky sweet all at once. A Live Girl favourite
6. Aurore Nomade by The Different Company Cinnamon, nutmeg, davana, ylang-ylang, geranium, clove, plumeria, immortelle, sandalwood, amber, vanilla and musk create a warm and sexy skin scent
7. Sarrasins by Serge Lutens A dark purple elixir of spicy jasmine, tuberose, and musk