Our ability to smell comes from specialized sensory cells located in a small patch of tissue high inside the nose. These cells connect directly to the brain.
Our sense of smell helps us enjoy life. We may delight in the aromas of our favourite foods or the fragrance of flowers. And our sense of smell also provides us with a warning system, alerting us to danger signals such as a gas leak, spoiled food, or a fire. Any loss in our sense of smell can have a negative effect on our quality of life. It can also be a sign of more serious health problems.
Without the sense of smell, familiar flavours such as chocolate or oranges would be hard to distinguish. Without smell, foods tend to taste bland and have little or no flavour. Some people who go to the doctor because they think they’ve lost their sense of taste are surprised to learn that they’ve lost their sense of smell instead.
Smell is the most sensitive of the senses and can remind us of things that we have experienced in the past because it is linked to the part of the brain that houses memories. This is why, when we smell something, we can (and often do) have memories and/or associations with it; for example orange, clove and cinnamon might remind us of Christmas, and a particular perfume or aftershave may remind us of previous partners or friends. The aromas from wood burners, or baking bread may remind us of childhood experiences.
Because smell affects the memory and emotion part of the brain, if we like the smell of something we buy, we are likely to continue buying it. This is why many companies add fragrance to their products such as soap or washing powder. Even those in the food industry use fragrance chemicals known as flavours or aroma chemicals to their products to entice buyers.
The sense of smell peaks when we are in our late teens and then begins a gradual decline. When their smell is impaired, some people change their eating habits; perhaps eat too little and lose weight and others might eat too much and become over-weight. As food becomes less enjoyable, we might begin to use too much salt to improve the taste. This can be a problem with certain medical conditions, such high blood pressure or kidney disease. And in severe cases, loss of smell can lead to depression.
Humans have five to six million odour detecting cells but that is nothing compared to the animal kingdom. Rabbits have 100 million such cells and dogs have about 220 million.
Dogs' sense of smell overpowers our own by huge orders of magnitude—it's 10,000 to 100,000 times as acute, scientists say. "Let's suppose they're just 10,000 times better," says James Walker, former director of the Sensory Research Institute at Florida State University, who, with several colleagues, came up with that jaw-dropping estimate during a rigorously designed, oft-cited study. "If you make the analogy to vision, what you and I can see at a third of a mile, a dog could see more than 3,000 miles away and still see as well."
But don’t be too quick to envy your dog. Imagine what it must be like to be in a crowded sports stadium on a hot day. The body smell of 10,000 sweating spectators would be overpowering.
Rev. Alan Stuart Ex missionary to Korea, Retired Minister, UCA
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