The Science Behind Fragrances

Most of us appreciate the power of a really well-blended cologne. A lot of men swear by cologne as one of the best ways to really pull together their whole look. And the scent is so important in a social aspect as well. Though still not entirely understood and largely unconscious, the scent has a lot to do with social relationships and interactions. Basically, how you smell may actually be a defining factor as to why someone finds you attractive or not. This has led men to the understanding that with a bit of trial and error, they can find their perfect, soon to become signature, scent.

Smell and scents in general work in a unique way when it comes to sensory perception. Not many people often consider how smell actually works and how fragrances like those used in colognes are actually received and processed by our senses, translating into a particular scent. What seems like a pretty simple concept suddenly got much more complicated and far more interesting than one might have thought at first glance.

Something a lot of people might not know is just how old the art of personal fragrances is. Historically, we can find evidence from some of the oldest civilizations – like the Sumerians and Egyptians – that showed that they used scented oils and a variety of products designed to achieve the desired smell. Families of higher class and status tended to have a wider range of increasingly exotic fragrance combinations. In part, scented oils helped mask the smells of human sweat as these were warmer locations. It also helped keep people smelling fresh as, well, hygiene just wasn’t what it is now back then – partly due to lack of access to sanitary facilities, and partly because of a lack of understanding about the connection between hygiene and health.

While compared to many other animals, we have a pretty poor sense of smell as humans, it is still good enough that our emotions and moods and even behavior can be affected by it. What started out as a way to help mask personal odor or show one’s status has now become a multi-billion-dollar industry.

Humans have about 50 million scent receptors. Scent molecules are absorbed by a thin membrane in the nasal cavity. Cilia, which are small, hair like protrusions, then send the appropriate signals to one of the four areas of the brain that process and manage olfactory inputs. The ability to perceive smells, while it starts in the nose, actually arises from the frontal cortex. The hippocampus is what will tie particular scents to certain memories. The amygdala and hypothalamus are responsible for the physical and emotional responses we have to certain smells. In essence, our nose is merely the conduit by which the brain processes and perceives scent.

This helps to explain why certain scents, like pine, are associated with feelings of home and family or memories of Christmas. It is due to the connections that our brains make to these smells that happen at an unconscious level but have a very real effect on our mood and even our behavior. Who would have thought the process of smelling a new cologne was actually so complex? (Other than scientists, of course.)

There are many scientists who believe that our olfactory system is one of the oldest bodily systems we have, meaning it evolved before some of the more complex elements of our nature and bodily processes did. The scent, while not as strong to us as some other animals, is a powerful thing that can have real effects on the mind and body. Though most of us don’t realize it, our scent has a lot to do with how attractive we are to another person. This is a unique scent that nobody else has and is part of what lets our kin know that we are, well, kin.

The process by which a smell is actually perceived is a rather complicated process and to some people’s surprises, takes place almost wholly in the brain. That is, the perception of smell is not trying a physical response, it is the way the brain processes and associates different scent molecules that are absorbed in the nose and the signals of which are transmitted from the nose to the olfactory areas in the brain.

Fragrances are almost as old as civilization itself. The oldest evidence of perfume-making dates to the Bronze Age, nearly 4,000 years ago. Ancient Egyptians distilled botanical fragrances like attar and lily not only to smell better but as a sign of social status. The first chemists were perfumers who worked in Mesopotamia. Perfume-making has evolved from basic distillations of plants and essential oils available only to the wealthy into a booming industry that makes billions of dollars in profit a year, and all of it depends on a part of the body we often overlook: the human nose.

Despite what science has believed until fairly recently, humans actually have a good sense of smell. While we can’t compare to dogs, who have a whopping 230 million smell receptors compared to our 50 million, humans are still able to discern more scents than scientists originally thought. Our noses work by collecting scent molecules when we inhale. These molecules are then dissolved in a thin membrane located a few inches into the nasal cavity. After this happens, small hairs called cilia send electrical signals to the olfactory bulb, which hooks directly into four different areas of the brain. The frontal cortex is responsible for our ability to perceive the scent itself. The hippocampus provides context for the smell in the form of memory, while the amygdala and hypothalamus are responsible for emotional and motivational undertones. It’s no surprise, then, that the scent of pine can summon memories of Christmas, while Petrich or, a mixture of plant oils and dust, can take the person back to a rainy afternoon.

The human nose can detect more than 1 trillion individual odors.

Our olfactory sense (sense of smell) is believed to be our oldest evolved sense.

Smells can evoke emotions and memories before they are properly identified.

Cosmetic companies and perfumeries spend billions of dollars a year catering to our much-maligned sense of smell. While still used as a status symbol (some colognes can cost hundreds of dollars), most fragrances are marketed as making the wearer more attractive to the opposite sex. A woman may consider a man who wears cologne containing musk to be attractive because of the corresponding association of musk with virility. Vanilla-scented perfume can conjure memories of baked goods and make the wearer appear more approachable and open, while astringent or sharp odors can make them seem closed-off and unpleasant. Scents like musk are perceived as more masculine and powerful, making them the basis of almost all colognes (and not a few perfumes), while flowery scents are typically considered feminine. However, this isn’t always the case. Because our sense of smell is linked so heavily with memory, an odor that is considered attractive by one person can be off-putting to another.

Like in all mammals, our noses have a say in who we are attracted to, but not in the way scientists once thought. While there is little evidence to suggest that colognes and perfumes that contain human pheromones are effective, there is plenty of evidence to suggest that how we smell not only affects how others perceive us but how we view ourselves. In one study, men who wore cologne not only behaved more confidently, but they were also judged to be more confident and therefore attractive by women based only on visual cues. Several studies have shown that women don’t choose perfume that they feel is attractive to others but to themselves, often choosing scents that complement their natural body odor.

Culture plays a large role in what people find pleasant when it comes to fragrances.

Natural musk is derived from the glands of mature musk deer, which were almost hunted to extinction.

Some scents, while indiscernible, can still cause subtle changes in mood.

When compared with other primates, humans actually produce a high amount of pheromones.

While pheromones may be out as an attractor, women can detect whether some else is too genetically similar to their major histocompatibility complex, or MHC, by smelling their sweat. The sweat of men who were genetically similar was consistently voted to smell worse than those who were not.

Perfumes react differently depending on individual body chemistry and how much time has passed between applications.

Pheromones can change if exposed to the elements. Androstenol, which is present in fresh sweat, is considered attractive to some women. When androstenol is left exposed to air, it oxidizes into androstenone, which is generally considered unattractive.

While scientists and perfumers may debate the usefulness of perfumes that contain human pheromones, there is evidence that at least one scent does have an effect on a woman’s sexuality. In 1966, Christian Dior was the first perfumery to use the chemical hedione in their Eau Sauvage perfume. The perfume became popular with both men and women. So many women chose to wear Eau Sauvage as their personal perfume that Dior released Diorella, a version marketed specifically to women. Other perfumers followed suite, adding hedione to their own fragrances.

So what made Eau Sauvage so popular? Though scientists at the time didn’t know it, hedione activates a very specific pheromone receptor in humans. This receptor activates areas in a woman’s hypothalamus that stimulates sexual awareness by releasing sex hormones.

Whether you’re wearing a fragrance to feel more confident, attract a mate, or display your social standing, the science behind how you smell is a fascinating mix of the perfumer’s expectations and a buyer’s personal experience. It’s little wonder that there are thousands of fragrances ranging from simple oils to multilayered creations designed to change with the wearer’s body temperature.

There are perhaps only five pheromone receptors still active in humans.

Other animals are attracted to human colognes. A favorite of big cats is Calvin Klein’s Obsession cologne for Men.

Research has found that the scent of pumpkin pie and lavender increased penile blood flow by 40 percent.