Greek philosopher and biologist Aristotle had his reasons for concluding that we have only five senses — hearing, sight, smell, taste and touch — but research has since expanded his little cluster and shown that we actually have at least 32.
This is based on our understanding that a sense derives from a ‘sensor’ (or receptor) that responds to a specific change.
So our senses include not just sight (which depends on sensors in the eyes detecting light of different wavelengths) but ‘temperature’ (experienced through sensors in the skin), ‘fullness’ (sensors in the stomach) and ‘pain’ (where sensors in our skin and in our bodies detect signs of damage to cells).
All of these sensory processes are fundamental to so much of our mental and physical experience — from allowing us to get out of bed and descend a staircase safely to enabling us to identify and avoid danger, eat what we need and not what we don’t
Inside our tissues there are also sensors responsible for vital processes, such as our heart rate, bowel movements and balance systems — these also count as ‘senses’.
The detection of a change triggers a signal, usually to the brain, which processes a response. This might be a conscious one, such as seeing colour, or feeling hunger or pain; or an unconscious response, such as a subtle change in blood pressure.
All of these sensory processes are fundamental to so much of our mental and physical experience — from allowing us to get out of bed and descend a staircase safely to enabling us to identify and avoid danger, eat what we need and not what we don’t. If these senses are damaged, it can cause a huge range of problems from hearing loss to getting lost.
What’s more, there is evidence that we can not only protect our senses but also train them to be better, which can influence practically every aspect of our lives, as I explain here.
Try fish scent to be more analytical
Our sense of smell helps us to decide whether something will be safe and nutritious, or dangerous and deadly. It’s our sense of smell that tells us not to take a mouthful of pungent fish, for instance. This response can have fundamental effects not just on our actions but also on our thoughts.
In order for us to smell something, first its molecules evaporate so they can be inhaled — they must also then dissolve in your nasal mucus, where the smell receptors lurk. These send their signals to the brain, which reads these smell ‘barcodes’ and interprets them.
And this is where that pungent fish comes in. When we’re not convinced about something, we might say it ‘smells fishy’. Norbert Schwarz, a professor of psychology at the University of Southern California recently led research showing just how far the ‘smells fishy’ metaphor can go.
Volunteers were given a document to read and those who were sitting at a desk that had been spritzed with a little fish oil were more likely to spot mistakes in the text. The fish smell seemed to raise their suspicions generally and, as a result, they were more critical of the content of the document.
So to boost critical thinking, you could do worse than spray a little fish oil around.
Boost smell sense for better sex life
With age, not only do you lose smell sensors but your capacity to grow new ones declines. This decline can be mitigated.
Modern life — particularly air pollution and certain respiratory viruses (including Covid-19) — poses threats to our sense of smell that are hard to avoid.
But our sanitised modern environments are also a threat, as it’s important to engage regularly with a variety of odours to preserve and enhance your sense of smell. How can you do that when you are going from a clean house to a valeted car to an air-conditioned office?
A treatment that’s recommended is to sniff a range of smelly substances regularly at different intensities, such as lemons, laundry detergent or garlic. Practise smelling and it may even improve your sex life.
In 2018, a German team reported that people who are more sensitive to smells enjoy sex more.
It is thought that an enhanced ability to smell increases arousal.
A treatment that’s recommended is to sniff a range of smelly substances regularly at different intensities, such as lemons, laundry detergent or garlic. Practise smelling and it may even improve your sex life
Why it’s hard to stop at one cake
The five basic taste qualities are sweet, salty, umami, sour and bitter. We have different receptors for each type, which in turn trigger a different response from the brain, so each taste counts as its own ‘sense’.
Our modern diets, combined with a lack of exercise, are making us fat — and that is bad news for our sense of taste.
It has been known for some time that obesity blunts taste. In 2018, a U.S. group came up with the most convincing evidence to date as to why: low-level, body-wide inflammation, caused by being overweight, upsets the normal balance of taste cell death and renewal.
Because we gain a feeling of reward from eating — and taste signals to the brain are critical for that — it’s thought that someone with a weaker sense of taste has to eat more to gain the same level of reward that a person with a healthy taste system would enjoy.
Obesity and poor taste are clinched in a downward spiral, encouraging and worsening each other. But overweight or obese people who lose weight can enjoy a taste restoration.
Even if you are a healthy weight, be careful about how much sugar you eat. There is some evidence that a high-sugar diet reduces the response of sweet-taste receptors. This would make the same slice of cake taste less sweet, which could encourage you to eat more of it.
Our modern diets, combined with a lack of exercise, are making us fat — and that is bad news for our sense of taste. It has been known for some time that obesity blunts taste
Don’t mince your words if in pain
Pain is one of the ‘new’ senses, that we feel when our bodies detect damage. In this case, our damage sensors — our nociceptors, found throughout the body — alert our brain to a clear threat. This usually results in pain sensations.
Damage sensors can respond to three types of stimuli: extreme temperatures, hazardous chemicals and mechanical impact (such as the slicing or crushing of cells).
What we feel can be influenced in a number of ways — for instance, we produce our own painkillers, including endorphins. But you could also swear.
In a 2016 study at Keele University, volunteers were asked to plunge their hands into ice-cold water for as long as they could. Some were allowed to swear while they did this, and these people said they felt less pain.
It’s not entirely clear why swearing helped, but it might be because it triggers the ‘danger’ flag in the brain, which can dial down pain.
If you have just bashed a limb, rubbing can help. This is because pain and touch signals are integrated in the spinal cord, so swamping the touch signals can reduce the damage signals.
In a 2016 study at Keele University, volunteers were asked to plunge their hands into ice-cold water for as long as they could. Some were allowed to swear while they did this, and these people said they felt less pain
You’ll never tire of a warm cuddle
When you are feeling pleasantly warm, you are in a comfortable zone, with your body sensors that detect temperature not having to work on heating you up or cooling you down.
But there’s more to this feeling of warmth: from our earliest moments, we come to pair the essential presence of a carer with perceptions of bodily warmth.
An interesting feature of our bodily warmth-sensing system is that while our cold temperature receptors can become sensitised to prolonged stimulation (so, for example, after a little time in the sea, you feel the cold less), warmth receptors don’t. This means that you can keep on perceiving and enjoying physical human warmth as long as it lasts.
And animal warmth, too: dogs and cats have a body temperature that is just a little higher than our own, and part of their psychological boost may be down to the physical warmth they bring.
When you are feeling pleasantly warm, you are in a comfortable zone, with your body sensors that detect temperature not having to work on heating you up or cooling you down
To prevent a fall, wear a blindfold
You may also try moving around your house with your eyes shut or blindfolded. Turn off vision and you’re instantly so much more aware of signals from your body
Body mapping is another of the ‘new’ senses and describes our intuitive sense of where our various body parts are located in space.
Whether you are simply staying upright on a bus or climbing Mount Everest, both depend on this so-called proprioception.
For older people, in particular, a decline in proprioception makes them more likely to fall. The good news is that it can be trained. Moving to music can improve your stability and control.
Climbing trees, walking along balance beams, crossing stepping stones (which you can simulate at home, using small mats placed on the floor) work, too.
You may also try moving around your house with your eyes shut or blindfolded. Turn off vision and you’re instantly so much more aware of signals from your body.
‘Hidden’ senses help memory
Other inner senses are also vital. Receptors in and around the heart send sensory signals every time your heart contracts to keep your brain informed about the frequency and strength of your heartbeat.
This is critical for blood-pressure control. Your brain keeps a close check on what internal changes are happening with a network of specialised sensors. The vagus nerve carries sensory information from the heart (and lungs and digestive tract) to the brain. Strong activity is known as good ‘vagal tone’.n
You can check your vagal tone by counting your pulse with a finger on your inner wrist. Does it speed up a bit when you’re breathing in, and slow down when you’re breathing out? If so, that’s good: it reflects that the vagus nerve is functioning well. The bigger the difference between the two, the higher your vagal tone.
People who are overweight and do little exercise tend to have low vagal tone, while exercise helps train it. People with a strong vagal tone are better at regulating their blood sugar levels and are less likely to have cardiovascular disease or a stroke.
Listening to music keeps ears young
If you want to protect your hearing, avoiding very loud noises is clearly a stand-out strategy.
Studies also suggest musical training enhances performance on a range of listening tests.
‘The brain’s response to sound can be enhanced by making music on a regular basis,’ said Nina Kraus, an auditory neuroscientist at Northwestern University, Illinois, and an amateur musician.
‘Biologically, the response to sound in a musician can look like what you’d expect in a younger person.’
In a seminal study she published in 2004, 55- to 70-year-olds were given challenging computer-based listening and memory tasks over 40 hours — by the end, they were notably better at perceiving speech against background noise.
If you want to protect your hearing, avoiding very loud noises is clearly a stand-out strategy. Studies also suggest musical training enhances performance on a range of listening tests
Women are more sensitive to the cold- and pain
In practically every type of sensing that has been tested, women are more sensitive than men. They are more responsive to scents, tastes, touch, even to pain.
Exactly what underpins this sense gap is debated. But it is likely to be at least partly because of the way the female nervous system handles sensory signals rather than differences in the sense organs themselves.
For many women, their sense of smell is far less constant than it is for men. The stage of the menstrual cycle, pregnancy, menopause — all are associated with changes in smell and also taste.
And if there are rows in your house about whether the thermostat should be turned up or down, odds are there’s a woman on one side of that argument and a man on the other.
In this case, the cause is likely to be about basal metabolic rate, the amount of energy that has to be burned to keep the body functioning while you are doing nothing. Men have a metabolic rate that is up to a third higher than a woman’s, meaning they produce more heat.
To get their skin temperature within the zone that both sexes consider comfortable (around 33c (91f)), they need less heat input from surroundings. So the room temperature that men report feeling pleasantly warm in (about 22c (72f)) can be up to three degrees cooler than for women (who report preferring around 25c (77f)).
Eyes aren’t just for seeing with
You have many body clocks, which help to coordinate everything from waking to digestion. But the master clock lies in the brain. To operate efficiently, this needs to know when day is breaking and night is falling. It gets this information from the eyes.
Experiments have revealed that animals that are blind still sense light levels because of a protein called melanopsin in their retinas, and use this information to control regular daily biological rhythms.
This control is known to be important for sleep as well as physical and mental health. To keep the master clock in check, expose your eyes to bright light in the morning but not in the evening.
If you can, walk to work — and try to avoid wearing sunglasses, especially in the morning. In the home, use plenty of bright lights in the daytime — but make them dimmable, so that the intensity can be reduced in the evenings.
Adapted from Super Senses: The Science Of Your 32 Senses And How To Use Them by Emma Young, published by John Murray on April 1 at £20. © Emma Young 2021.
To order a copy for £17.60 (offer valid to 6/4/21; UK P&P free on orders over £20), visit mailshop.co.uk/books or call 020 3308 9193.