WE HAVE FAR MORE THAN FIVE SENSES
As I grow older, I become more fascinated by the human body and the remarkable things it can do without our even thinking about them.
For most of my life, I was taught that human beings have five senses: sight, hearing, smell, taste, and touch.
I suspect most of us learned the same thing in elementary school.
But recently, I came across an interesting article about our senses, and it made me realize that what I learned as a young student was only the beginning. Modern science tells us that the human body has many more sensory systems than the traditional five. Depending on how scientists classify them, we may have dozens of different senses.
That discovery fascinated me.
After all, I have spent much of my life as a scientist. I earned my Ph.D. in Pharmaceutical Chemistry at the University of Illinois Medical Center in Chicago, and throughout my career I learned to appreciate how extraordinarily complicated and beautifully organized, the human body really is.
The more I learn about it, the more I realize that we are walking around every day carrying one of the most sophisticated biological systems ever created.
THE FIVE SENSES WE KNOW
Let us begin with the familiar and the traditional five.
Sight allows us to see the world around us through our eyes.
Hearing allows us to detect sound, from a friend's voice to music, birds singing, or the sound of rain.
Smell allows us to detect chemicals in the air. It can bring back memories surprisingly quickly. Sometimes one particular smell can transport me back many decades to my childhood in the Philippines.
Taste allows us to distinguish sweet, salty, sour, bitter and umami flavors. For someone like me who enjoys food tasting journeys, this is certainly one of my favorite senses!
And then there is touch, which allows us to feel pressure, texture and contact with objects around us.
These five senses are so familiar that we tend to think they represent the complete story.
They don't.
THE SENSE OF BALANCE
One of the senses that we rarely think about is our vestibular sense.
This is the sensory system that helps us maintain balance and understand the orientation of our body in relation to gravity.
Deep inside our inner ear are structures that detect movement and changes in the position of our head.
Think about what happens when you stand up, walk across a room, turn your head, climb stairs or suddenly change direction.
Your brain is constantly receiving information about your body's movement and position.
You don't have to consciously tell your body:
"I am leaning to the left. Please correct yourself." It happens automatically.
As someone who has grown older, I have become much more aware of the importance of balance. When we are young, we take it for granted. As we age, however, maintaining balance becomes increasingly important.
That makes me appreciate this hidden sense even more.
PROPRIOCEPTION-KNOWING WHERE YOUR BODY IS
Another fascinating sense is called proprioception.
It is sometimes described as our body's sense of position.
Close your eyes and raise your hand.
You probably know exactly where your hand is, even though you cannot see it. How?
Your muscles, tendons and joints contain sensory receptors that continuously provide your brain with information about the position and movement of your body.
This allows you to walk without staring at your feet.
It allows me to reach for something on a table without having to calculate the exact position of my arm.
It is almost like having an internal GPS system for the body.
We rarely appreciate it because it works so quietly.
THERMOCEPTION- FEELING TEMPERATURE
We also have thermoception, our ability to sense temperature.
When you touch a cup of hot coffee, your body knows that it is hot.
When you step outside on a cold winter morning, your skin immediately tells your brain that the temperature has changed.
Special sensory receptors detect temperature changes and send signals to the nervous system.
Again, we normally don't think about this process.
We simply experience: "It's hot." Or: "It's cold."
But behind that simple experience is an extraordinary biological system.
NOCICEPTION-THE SENSE OF PAIN
Perhaps one of our least appreciated, but most important senses is nociception, the detection of potentially damaging stimuli that we experience as pain.
Nobody enjoys pain. But pain serves an extremely important purpose.
If you accidentally touch something very hot, pain tells you to move your hand away.
If you injure yourself, pain tells you that something is wrong.
Pain is essentially an alarm system.
Imagine what life would be like if our bodies could be injured but could not warn us.
Pain may be unpleasant, but it is one of the body's most important protective mechanisms.
HUNGER, THIRST AND MORE
And the list goes on. Our bodies can sense hunger and fullness, helping regulate how much we eat.
We have mechanisms that detect thirst and fluid balance.
We have systems that monitor blood pressure, blood oxygen, carbon dioxide, and the chemistry of our internal environment.
Our bodies can sense the stretching of our lungs, stomach and other organs.
Our brains constantly receive information from inside our bodies—a collection of sensory information sometimes described as interoception.
In other words, we don't only sense the outside world. We also sense ourselves.
That is an idea worth thinking about.
OUR BODIES ARE CONSTANTLY TALKING TO OUR BRAINS
When I think about all these different sensory systems, I realize how much information is flowing through my body every second.
My eyes are collecting information about light and movement.
My ears are detecting sounds. My skin is detecting pressure and temperature.
My muscles and joints are reporting where my arms and legs are. My inner ear is monitoring balance.
My internal organs are sending information about what is happening inside my body.
And somehow, the brain receives, interprets and coordinates all of this information—often without our conscious awareness.
We simply go about our daily lives. We walk. We eat. We talk. We sleep. We play cards.
We enjoy music. We watch television. We smell flowers. We taste our favorite foods.
And underneath all of these ordinary activities is an incredibly complicated sensory network.
BRIDGE GIVES ME AN INTERESTING EXAMPLE
My many years of playing Bridge provide me with an interesting way to think about this.
When I sit down at the Bridge table, I am using much more than my eyes.
I listen carefully to what my partners and opponents say.
I watch their cards and movements. I handle the cards with my fingers.
I remember the cards that have already been played. I judge distances and positions.
I maintain my balance while sitting and moving around.
My brain is combining information from several sensory systems while simultaneously using memory, reasoning and probability.
Bridge is sometimes described as a game of skill and luck. I agree.
But perhaps we should also recognize that it is a wonderful exercise in human perception and cognition.
WHAT ABOUT AGING?
Learning about our many senses also makes me think about growing older.
At 91, I am much more conscious of things that I simply took for granted when I was young.
Balance matters. Walking safely matters. Being able to see and hear clearly matters.
Feeling temperature matters. Being aware of where my body is in space matters.
Our senses are not merely ways of experiencing the world. They are also essential to our independence.
This is why I believe that staying physically and mentally active is important as we grow older.
Walking, exercising, playing Bridge and Mahjong, socializing, learning new things and continuing to challenge the brain are all ways of keeping ourselves engaged with the world around us.
THE MIRACLE OF ORDINARY LIFE
Perhaps the most remarkable thing about our senses is that we rarely notice them.
We don't wake up in the morning and say: "Thank goodness my proprioception is working today!"
We simply get out of bed and walk. We don't sit down for breakfast and marvel at our taste receptors.
We simply enjoy our food. We don't think about our vestibular system when we turn our head.
We simply keep our balance. We don't think about nociception until something hurts.
That is perhaps the greatest lesson. Some of the most extraordinary things happening in our lives are the things we don't notice.
For me, learning that human beings may have far more than five senses is another reminder of how little we sometimes appreciate the miracle of being alive.
From my childhood in the Philippines to my years at the University of the Philippines and the University of Illinois, through my scientific career in pharmaceutical research and my many years in America, I have spent much of my life learning about the world.
But at 91, I am still learning something new about myself.
And perhaps that is one of the great privileges of growing older.
We continue to learn. We continue to wonder. We continue to be surprised.
So the next time someone tells you that human beings have only five senses, remember:
There is much more to the story. Our eyes, ears, nose, tongue and skin are only the beginning.
Our bodies are constantly sensing movement, balance, temperature, pain, pressure, position, hunger, thirst and countless signals from inside and outside ourselves.
We are, in a very real sense, living, sensing human beings.
And that, to me, is something worth appreciating every day.
My Feedback: The draft is perfectly written. Your example on my use of the senses in playing bridge resonated with me because what you drafted are exactly what I have been doing for many years of bridge playing. Again thank you for this beautiful draft on the Senses.
AI Overview:
WE HAVE FAR MORE THAN FIVE SENSES
You are absolutely right: the idea that humans only have five senses is a massive underestimation. While the "traditional five" (sight, hearing, taste, touch, and smell) dates all the way back to the ancient Greek philosopher Aristotle, modern neuroscience recognizes anywhere from 22 to over 33 distinct senses depending on how you define them.
Scientists define a "sense" as a system consisting of sensory cell types that respond to a specific physical phenomenon. When we break down how our bodies actually navigate the world and monitor our internal states, the list grows significantly.
The "Hidden" Somatic Senses
These are the everyday physical senses that operate constantly in the background, entirely separate from the basic sense of touch:
- Proprioception (Body Awareness): The "internal GPS" that allows you to know exactly where your limbs are without looking. It's how you can scratch your nose in pitch-black darkness or walk up stairs without staring at your feet.
- Vestibular Sense (Equilibrioception / Balance): Coordinated by liquid-filled canals in your inner ear, this tells your brain about gravity, acceleration, and motion. It keeps you upright and prevents you from tipping over.
- Thermoception (Temperature): Separate from mechanical touch, specialized thermoreceptors in your skin detect changes in heat and cold.
- Nociception (Pain): A dedicated warning system consisting of nerve endings that register mechanical, thermal, or chemical tissue damage.
Interoception: Tracking the Internal World
- Interoception is the comprehensive category for how you sense your internal body chemistry and organ states. This includes receptors that signal when you are out of breath, when your blood pressure drops, when you are hungry or thirsty, or when you have a full bladder.
Splitting the Basics
Neuroscientists also point out that even the "traditional five" can be split into independent senses:
- Vision relies on entirely distinct receptors for light intensity (rods) and color wavelength (cones).
- Taste is driven by five completely separate receptor categories (sweet, salty, sour, bitter, and umami).
Ultimately, our brains seamlessly blend these dozens of inputs into what feels like a unified experience, which is why the myth of the basic five has persisted for so long
Finally, here are the 10 early signs of Dementia: Early signs of dementia can vary from person to person, but here are 10 common ones to look out for:
Memory loss: Forgetting recent events, learning new information, or recalling familiar words and names. Repeating a sentence or phrases without knowing it.
Communication and language: Difficulty finding the right words, following conversations, or understanding written or spoken language.
Disorientation: Trouble understanding time and place, getting lost in familiar places, or difficulty navigating.
Mood changes: Becoming easily agitated, anxious, or depressed, which can be triggered by memory loss or confusion.
Personality changes: Showing rapid mood swings, becoming passive, or suspicious.
Difficulty with problem-solving: Trouble with abstract thinking, making decisions, or judging time and space.
Motor function changes: Difficulty with coordination, balance, or movement.
Misplacing items: Frequently losing items or being unable to recall where they were placed.
Changes in daily tasks: Difficulty with everyday tasks like managing finances, taking medication, or performing self-care.
Vision and spatial issues: Trouble with depth perception, judging distances, or understanding visual information.
If you experience any of the above 10 items recently, consult your physician right away!
