| Brief Guide to the sense of smell |
| The sense of smell |
| The nose is a cavity designed to moisten, filter and sense or smell the air that we take in. The air passes through the nasal cavity and over a thick layer of mucus underneath which lie the olfactory cells. Chemicals pass / diffuse through this mucus and then stimulate the underlying cells, which send messages to the brain about what it is that you are smelling. The mucus not only allows chemicals to reach the olfactory cells, but also protects them from drying out and damage. What we smell is often referred to as an odour; an unpleasant odour may be referred to as a stench, whilst a pleasant one may be termed a fragrance. The perfume industry spends many millions of pounds each year designing new perfumes and fragrances for men and women. The wine industry is obsessed with the bouquet of a wine, plant breeders go to enormous lengths to create flowers that add scent as well as beauty to the garden. |
| How does it work? |
| The smells are recognized because each smell molecule fits into a receptor cell like a puzzle piece, or so says one theory. The cells then send signals to the brain via the olfactory nerve. The brain interprets these electrical signals as the bouquet of roses, or the rotting fish that you've held up to your nose. The part of the brain that receives these messages is called the olfactory bulb; it is part of the cortex of the brain; it can then relay messages on to many different parts of the brain. |
| How sensitive is it? |
| We can detect over 10,000 different smells. However, dogs have one million smell cells per nostril, and their cells are significantly larger than those of humans, small wonder they train dogs to search for illegal drugs on people or in their luggage. Some people are born with a condition, known as Anosmia, which means that they are unable to smell or have a limited range of things that they can smell. Smell is one of our senses and an important one. Our sense of smell directly affects our sense of taste (Do you really enjoy a good meal if your have a bad cold?). Smell can also release emotions such as fear, happiness, and sexual desire. Some chemicals are particularly associated with the 'awakening' of the sexual response - pheromones. A male moth can detect a female by her smell or pheromone when she is miles away. The processing of smell information by the brain can affect the emotional balance of a person. The sense of smell is one of the bodies' protective mechanisms, for example, the detection of smoke or burning clearly has survival value, equally to be able to discern that food has 'gone off', has turned rancid or begun to rot - think of the smell of fish that is no longer fresh. This is caused by the chemical trimethylamine (TMA), (CH3)3N. Some unfortunate people have an inherited condition called trimethylaminuria, which means that they have a fishy odour about them (see Trinculo's description of Caliban, perhaps one of the first cases to be recorded in literature) |
| Why do things smell the way they do? |
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One widely accepted theory of why one molecule smells like it does is based on the work of a British scientist, John Amoore in the 1950s. He suggested that the receptors (in the lining of the nose) that send the signal from each aroma to the brain worked like a lock and key. The receptors were the locks and particular smells were the keys; people with anosmia had some of their locks missing. He reasoned that the combination of particular aroma/smell molecules with different shapes opened the 'nose locks' and sent an electrical signal to the brain, depending on the shape of the molecule.
However, in more recent times, another British scientist, Luca Turin has offered a different explanation. His idea centres not on the shape of molecules but on how they shake and vibrate. Each type of molecule has a slightly different pattern of shaking and vibration, rather like different tuning forks. He believes that it is the unique vibration and shaking of each molecule that is detected by the cells in the nose and then interpreted by the brain. The fact that smell, according to Turin's theory, invokes a spectrum (of different frequencies) like sight and sound might explain the strange and rare condition known as synaesthesia. This is where someone's senses are mixed up. Some musical composers claim to be able to hear in colours or smell sounds. The Nobel Prize winners, Axel and Buck have discovered on explanation for our olfactory abilities. They have shown that the human genome (our genetic make up) contains a 'family' of some 1,000 different genes that produce a similar number of olfactory receptor proteins. This represents nearly 3% of our total gene count, which estimated to be about 35,000; suggesting that smell to our ancestors and us was a very important sense indeed. |
| Trade in scents |
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There has always been a markets for scents. Trade routes opened up and introduced spices to other parts of the world and a wider range of scents could be made. Nowadays, perfumes have become a multi billion pound industry. People have used perfume, oils and unguents ( a semi-solid preparation like a cream) on their bodies for millennia. The early Egyptians used perfumed balms (some derived from Myrrh and Frankincense) as part of their religious rituals and later as part of their preparation for love making. Plants such as rose and peppermint were soaked in oils until a perfumed liquid was formed. This was then rubbed into the skin. Such performed oils are now much in fashion again, being used extensively in aromatherapy, just as they were centuries ago.
To find fragrances, try fragrances.co.uk. |
| How are scents made? |
In the past people often mixed their own potions using home methods creating their own aromatherapy products. Many homes had a still room where essences were steeped out of flowers and herbs. The essence of perfume making is simple. The trick is to put certain essential oils together creating a smell that you like. A perfume is made up of base notes (the smell stays the longest on your skin), middle notes (smell stays second longest), and top notes (smell of oil evaporates first and most obvious on first acquaintance). Because the oils evaporate at different rates, the perfume may smell different as time passes. The list below shows some of the various essential oils according to their base, middle and top notes.
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| How has the perfume market developed? |
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In the late 19th century, Grasse in Provence, France became a focus for flower and herb growing for the perfume industry. But it was only in the C20th that scents and designer perfumes were produced on a significant scale. Today, creating a 'liquor' (the term used to refer to a perfume in the industry) is in the hands of a few people particularly skilled at handling essences: they are known as "noses". One does not study for a diploma or a degree in order to become a 'nose. However, it does require a love of and an understanding of fragrances, achieved through many years of apprenticeship. Also a 'nose' does not smoke and will avoid anything and everything that might impair his or her olfactory talent. In 1921, Ernest Beaux created for Coco Chanel possibly the most famous perfume in the world, Chanel No.5. It has a floral top note of ylang-ylang and neroli, with a heart of blends of jasmine and rose lying on a woody base of sandalwood and vetiver. Chanel believed women should wear perfume wherever they hoped to be kissed! Today, some eighty years since its creation, a bottle of Chanel No.5 is sold every 30 seconds.
The successful launch of a perfume is not however simply a function of its component parts, it must also take account of the times in which we live, the target market / audience, the image that that the product is to convey (exclusive, sensual, sporting); the packaging of the product is also significant. There should be a synergy between the perfume, its image and its packaging. To find perfumes, visit perfumeshop.co.uk. |
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