We learned in school that humans have five basic senses. However, modern philosophers and neurobiologists argue that we possess a whole spectrum of senses that help us understand the world around us, our place in it, and how our bodies function.
This means that the theory of five senses is hopelessly outdated. One of its earliest proponents was the ancient Greek philosopher Aristotle. In his work De Anima (“On the Soul”), he described the “external mind” of humans, which includes the senses: sight, hearing, smell, taste, and touch. For centuries, the scientific community did not dispute the idea that only these five exteroceptive senses provide us with information about the external world. But now, scientists view this notion as an anachronistic myth.
Admittedly, there have been faint voices defending the so-called sixth sense, which is said to be responsible for telepathy and precognition. However, this idea has remained without substantial evidence.
Why Was Aristotle Wrong?
The thing is, our bodies do not just sense the world around us; we also sense the world within us. This involves awareness of things like hunger, thirst, heartbeat, lung movements, stomach activity, and much more. These sensations are collectively referred to as “interoception,” as reported by IFLScience.
They manifest when the body sends signals to the brain, particularly to an area known as the insula. This region processes and interprets these signals. In many cases, these signals may go unnoticed by our consciousness, but our brain constantly monitors them to maintain homeostasis—our bodily stability.
In addition to these internal sensations, we also have unrecognized senses that allow us to navigate space.
For instance, if we can maintain our balance while walking, stand on one leg, or walk a tightrope, we possess what is called equilibrioception. This sense of balance and orientation is controlled by our inner ear.
Then there’s thermoreception—the ability to detect and differentiate hot and cold temperatures; nociception—the capacity to feel pain; and proprioception—awareness of how our bodies are positioned. Thanks to the latter, we know, for example, where our hands are even without looking at them.
And that’s not all. Our ability to perceive the passage of time is known as chronoception. It is not governed by a single sense organ but rather a series of complex processes interpreted by our brain. Through chronoception, we understand how long events last and how they unfold.
By the most conservative estimates, scientists have currently identified 12 or 13 key senses. However, some researchers believe there may be more than 20. Interestingly, the animal kingdom is filled with additional senses, far exceeding our own.
What Unique Senses Do Animals Have?
One example is magnetoreception, which allows many species of mammals, birds, insects, and fish to navigate over long distances. In humans, this sense is underdeveloped.
Sharks and rays, on the other hand, possess electroreception, which helps them locate prey in murky waters.
Birds and certain fish are equipped with baroreception, enabling them to sense changes in pressure in the air and water. There’s also chemoreception—the ability to detect pheromones or specific chemicals, which is characteristic of scent-tracking dogs.
In any case, the list of senses is incomparably longer than the one we inherited from Aristotle.