Could you smell a rat?

Woman smelling bread
Woman smelling bread

As a man, I believe I have a strong sense of smell, also called olfaction. But, scientists have discovered that this is not true. Women actually have a sharper sense of smell than men.

I guess my belief stems from the fact that at home I am the first to shout, “What’s burning?” at the slightest smell of smoke. This is probably because I suffer from pyrophobia (an abnormal fear of fire) any detection of a burning odour is followed by my frantic check of every room to make sure all electrical appliances are disconnected.

Besides the smell of smoke I’m also quick to detect bad breath and body odour - even my own. And, when food has expired I’m the first one to complain of faint bad odour. Friends and family smile when I commend them for wearing a pleasant fragrance.

But, like many people, I take my sense of smell for granted.

Just how do we smell?

According to Livescience, we to be able to smell we breathe in air with odour molecules which then bind to olfactory receptors in the nose. The receptors send messages through the olfactory nerve to the olfactory bulb, located in front of the brain. Signals from the olfactory bulb tell the brain what is smelling.

Humans have five to six million receptors in their nose (rabbits have 100 million, and dogs have 220 receptors).

An average human can distinguish a whooping trillion smells!

Loss of smell - prediction of early death

Scientists at the University of Chicago recently linked the loss of smell in older patients to their death within five years.  The researchers claim an olfactory dysfunction is a stronger prediction of death than a diagnosis of heart disease, cancer or lung disease. Inability to smell does not cause death, but is sign that something has gone wrong.

Patients who lose their sense of smell face many challenges. One for example is that it’s difficult for them to detect when food has gone bad and because their sense of taste is affected patients may dislike food and make unhealthy eating choices. They are also less likely to pick up on danger signals such as a gas leak and their personal hygiene may suffer.

Scientists are not 100% sure how the loss of smell predicts early death, but one theory is that a loss of smell might be that the body is losing its ability to build key components which results in death.

Smell of happiness

Furthermore, if you've ever met someone who, without saying a word has made you feel happy, you may have picked the positive vibe up from the smell of their sweat.

According to research published in  Psychological Science we can detect happiness in the sweat of othersScientists report that when we are happy we produce chemical compounds, which can be detected in our sweat by other people.

Earlier research had already confirmed that negative emotions such as fear and disgust are detectable in our sweat. The findings that happiness can be communicated chemically, through someone’s sweat, interest to the perfume industry.

Read: Do people transmit happiness by smell?

The smell of a handshake

If that's not interesting enough it turns out that just like animals smell each other to become acquainted, we do too. This is according to research published by the Weizmann Institute of Science.

In the hand shake experiment  people smelled their hands twice as often after a handshake. The time spent smelling their hands was longer after a handshake. To test whether the hand sniffing was olfactory, the researchers observed that the hand sniffing reduced or increased when the researchers introduced different smells into the experiment. The scientists concluded that the sense of smell has an important role across and within genders.

How smell affects our mood

The Social Issues Research Centre says smell can trigger emotional reactions in humans. Humans link a particular smell to a particular experience or memory and this can change someone’s mood.

But can fragrances in themselves affect our mood?  The Oxford  University Press  journal says it can. Their Chemical Senses journals tested and proved that relaxing fragrances can reduce stress-induced muscle tension. The study showed that fragrances are powerful enough to counteract stress.

Various smells can alter our moods. For example the smell of vanilla reduces anxiety and stress by making you calmer, and floral scents make people happier. Peppermint stimulates the brain and makes us more alert while lavender helps you to sleep and cinnamon can sharpen your mind.

Read: Humans can smell fear

Sense of smell alarms

CNBC reported that 18-year-old inventor Guillaume Rolland took advantage of the sense of smell to develop an olfactory alarm which wakes people by producing a variety of 12 different smells which include peach and peppermint.  During trials, the product, SensorWake had 99% success rate in waking people up.

Smell disorders

It turns our that over half of the people between the ages of 65 and 80 experience a loss in their ability to smell.  More than 75% of those over 80 years experience a decreased olfactory function. In fact, by age 30 a good number of people start to lose their ability to smell.

People with smell disorders may experience reduced, distorted or no smelling ability. Smell disorders have many causes which include: ageing, smoking, sinus and upper respiratory infection, growths in nasal cavities, growths in the nasal cavities, head injury, hormonal disturbances , dental problems, exposure to harmful chemicals, many medications (e.g. antibiotics and antihistamines), cancer radiation treatment around the neck and head, Parkinson’s disease or Alzheimer’s disease.

These are some of the disorders related to our sense of smell:

Hyposmia is a reduction in the ability to detect smells.

Anosmia is when someone is completely unable to detect odours.

Parosmia is when the sense of smell I distorted. A pleasant odour will be detected as a foul smell and vice-versa.

Phantosmia is detecting an odour which  is not there.

How to sharpen you sense of smell or detect problems

Scientists came up with methods that help to sharpen your sense of smell. The Wall Street Journal suggests the following  exercises:

1. Close your eyes and taste vanilla ice cream and chocolate ice cream. If you cannot taste the difference you have a problem.

2. Hold a pad soaked in rubbing alcohol just beyond your chin. If you can smell the alcohol your sense of smell is most likely okay.

3. Regularly smell your food, tea or coffee before eating or drinking them. This sharpens your sense of smell.

4. Choose 3 to four pleasant (non –irritating) scents you like. Sniffing these 4 to 6 times a day stimulates different receptors in the nose to work.

Read more:

If you can't smell these 5 things you might be dying

Obese people may be more sensitive to food smells

A perfume that smells better the more you sweat?

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