Some Interesting Facts and Trivia About Odors

About Your Nose & Sense of Smell

What you actually "smell" with your nose are tiny little things that scientists call molecules. A molecule is the smallest piece that anything can be divided into without changing the properties of what it is and how your body reacts to it. A good example of this is water, which is made up of hydrogen and oxygen atoms, neither of which you could drink if you were thirsty.

When you breathe in through your nose, some of the air passes through a tiny chamber called an olfactory gland. It’s about half the size of an egg and located right behind your nose. Your olfactory gland has millions of "receptor" cells in it, and each one is mounted on a microscopic hair that sticks out and waves in the air currents. About forty of them must detect odor molecules before a smell is registered and sent to your brain.

Taste and Smell

We only taste four things: sweet, sour, salt and bitter. It's the odors we can smell with our noses that make things really taste unique. For example, wine's odors, not its taste, are what make it delicious. With a head cold, drinking wine is an entirely different experience. Talking with your mouth full expels taste molecules and diminishes the taste of food. There’s an easy kitchen science experiment you can try that’s a fun way to demonstrate this – The Blindfold Taste Test. Have someone wear a blindfold and feed them small pieces of different types of food, but hold a different piece of food under their nose while they’re trying to guess what it is they’re chewing on. Their guess will usually be what’s under their nose rather than what’s in their mouth.

An average person can tell the difference between 4,000 - 10,000 odors. When an odor is detected, your olfactory gland sends a message directly to your brain, into an area called the limbic system. The limbic system reacts immediately to the smell and if it "remembers" the smell, it can provoke very powerful emotions, images or nostalgia in your conscious mind, which can be either pleasant or unpleasant. Your reaction to odors has also been shown to affect your sub-conscious mind as well and can influence your behavior, moods and decision making.

Humans have seven primary odors that help them determine objects:
  1. Camphoric - Mothballs
  2. Musky - Perfume/Aftershave
  3. Floral - Roses
  4. Minty - Peppermint Gum
  5. Etheral - Dry Cleaning Fluid/Pears
  6. Pungent or acrid - Vinegar
  7. Putrid or foul - Rotten Eggs
Smell Facts
  • Women have a keener sense of smell than men do.
  • By simply smelling a piece of clothing, most people can tell if a woman or a man had been wearing it.
  • Each of us has an odor that is unique, just like our fingerprints.
  • Much of the thrill of kissing comes from smelling the unique odors of another's face.
  • Smells stimulate learning. Students given olfactory stimulation along with a word list retain much more information and remember it longer.
  • Many smells are heavier than air and can be smelled only at ground level.
  • We smell best if we take several short sniffs, rather than one long one.
  • Dogs have 1 million smell cells per nostril and their smell cells are 100 times larger than humans are.
  • Humans use insect warning chemicals, called pheromones, to keep away pesky insects.
  • People who cannot smell have a condition called Anosmia.
  • As you get older, your sense of smell gets worse. Children are more likely to have better senses of smell than their parents or grandparents.

Scientific Research Into The Sense of Smell (Olfaction)

The environment is full of natural and manmade odors. We are surrounded by, and indeed are capable of sensing, an enormous variety of fragrances and aromas. Yet our olfactory world does not usually overwhelm us because basic mechanisms of perception and higher cognitive processes help make order out of olfactory experiences.

The perception of an odor usually fades over time, even if the chemical producing it remains in the environment. It has long been known that such adaptation occurs in the short-term. With constant or repeated exposure, the ability to perceive an odor declines within seconds or minutes. Research has shown that people who are constantly exposed over the course of several weeks to an odor at home or at work show a decline in sensitivity to that odor. This decrease in sensitivity can last for up to three weeks after the odor is removed. Reduced sensitivity to an odor produced by exposure to another odor is known as "cross-adaptation." Studies have shown that cross-adaptation can be used as a strategy for odor control when pleasant-smelling aromas produce adaptation to unpleasant odors.

Changes in response to odors cannot be attributed solely to decreased sensitivity. People's perception of an odor is also shaped by expectations and pre-existing attitudes about that odor. For example, the time course and degree of adaptation for an odor is significantly different when people believe they are being exposed to a natural essence, as compared to when they think they are being exposed to a hazardous chemical even when they are being exposed to exactly the same odor. Cognitive factors thus play an important role in response to and perception of odors.

The sense of smell is present at birth and young infants respond to odors, preferring scented toys to unscented ones. It is well known that the ability to smell and, to a lesser degree, to taste declines with age. The ability to detect certain odors depends on an individual's genetic makeup. People who, for genetic reasons, cannot detect a particular odor are said to have a "specific anosmia." Research has shown that many people with a specific anosmia for an odor can be induced to perceive it if they are repeatedly exposed to that odor. This indicates that heredity and experience can interact to shape olfactory perception. Research has shown that such sensitivity can also be induced in strains of mice with a specific anosmia. They are now using these animals to explore the neurological bases of this phenomenon and to identify and isolate the gene(s) that are involved.

Odors are often thought to provide the best memory cues because some of our oldest and most emotionally laden memories are associated with odors. Accuracy and emotional content of memory can be affected by odor-associated cues. The accuracy of a memory is not affected by the type of sensory cue for example, whether it is olfactory or auditory. Instead, a memory that is triggered by an odor is experienced as being more emotionally intense and evocative than a memory triggered by any other type of sensory cue. Research has shown that the distinctiveness of an odor and the emotional context in which it is experienced are key variables in the formation of memories associated with odors. Memory is enhanced when learning takes place in the presence of a novel odor, and is further facilitated if learning occurs during a heightened emotional state.

Odors can effect motor and clerical performance, as well as on mood and behavior. For example, research has looked at the effect of odors on time spent in public settings, such as museums and shopping areas, on a variety of social interactions, and on consumer attitudes. Here, too, cognitive factors play an important role. In particular, beliefs about both the odor and the context in which odors are experienced are important determinants of how odors affect performance, mood, and behavior.

The Dark Ages of Smelling

A keen sense of smell is now accepted as part of the good life - coffees, wines, cheeses, and gourmet foods would all be lost on us if we lacked our immense range of smell. However, this faculty wasn't always appreciated.

  • The ancient philosopher Plato looked down on smell as a lowly instinct that might lead to gluttony and lust, while vision and hearing opened one geometry and music and were therefore "closer to the soul."
  • During the 18th and 19 centuries, it was commonly believed that many diseases were caused by smells. Odors from corpses, feces, urine, swamps, and Earth fissures, were called "miasmas" and were thought to have the power to kill you. To ward off these smells, people carried and inhaled "antimephitics," such as garlic, amber, sulfur and incense. When exposed to miasmic odors, people did not swallow their saliva, but spit it out. The Viennese physician Semmelweis was ostracized by colleagues when he declared that washing one's hands, not breathing antimephitics, would stop most disease from spreading.

According to some sources, the stethoscope was invented not to hear the heartbeat better, but to give doctors some distance from a patient's bodily odors.