The Senses You Didn’t Know You Had (Spoiler: We Might Have More Than 5)

It's Saturday, February fourteenth, and from HigherIQ, Happy Valentine's Day! We're going to spend it talking about your body — specifically, the parts of it you've been completely ignoring. There's a good chance you woke up this morning, made coffee, and experienced about twenty-five different senses before you even checked your phone. You just didn't know it because a Greek philosopher two thousand four hundred years ago told you there were five, and nobody ever bothered to double-check. We're also going to talk about the origin of life — and how it might have started in the last place anyone expected. So here's something that should probably bother you more than it does. The idea that humans have five senses comes from Aristotle. De Anima, around three fifty BC. Same guy who said the world was made of five elements, that the heart was the seat of intelligence, and that women had fewer teeth than men. We've corrected everything else he got wrong. But the five senses? That one just stuck. Preschool books, science class, the entire "sixth sense" framework. All of it traces back to a guy who never saw a microscope and thought the brain existed to cool the blood.

A new article from Barry Smith, director of the Centre for the Study of the Senses at the University of London, lays out the current thinking from neuroscientists — and the number isn't five. It's somewhere between twenty-two and thirty-three. That range comes from Charles Spence's lab at Oxford, one of the most respected perception research groups in the world, and the exact count depends on how you define a "sense." Which, it turns out, is a genuinely hard question. Here's the standard neuroscience definition: a sense is a system with its own specialized receptors and its own dedicated neural pathways. Under that framework, "touch" alone breaks into at least four separate senses — pressure, temperature, pain, and itch. They use different receptors, travel through different nerve fibers, and get processed in different parts of the brain. They're about as related to each other as sight is to hearing. We just lumped them together because they all happen through the skin. Same thing with taste. What you think of as "tasting" food is actually three sensory systems at once — gustation from your tongue, retronasal olfaction from odors traveling up the back of your throat as you chew, and the tactile sensation of texture and temperature. You don't have raspberry receptors on your tongue. There's no taste arithmetic for fruit flavors. Your tongue detects five basic categories. Your nose fills in everything else. That's why a crunchy apple tastes different from a mealy one even when the chemical compounds are identical. But the senses that really rearrange your understanding are the ones you've been using every second of your life without knowing they existed. Proprioception is probably the most important sense you've never heard of. It's how you know where your body is in space without looking. Close your eyes right now and touch your nose. You didn't fumble around for it. You didn't have to think about where your hand was going. That's proprioception — specialized receptors in your muscles, tendons, and joints constantly reporting your body's position to your brain. Without it, you couldn't walk, drive, type, or reach for a glass of water in the dark. And yet it never made the list.

Then there's interoception — your sense of what's happening inside your own body. You feel your heart rate speed up before a big meeting. You notice a subtle tightness in your chest when you're anxious. You feel hunger. You sense a full bladder. None of that is touch, or taste, or any of the five. It's a separate sensory system monitoring the state of your internal organs, and recent research suggests that people with sharper interoception tend to be better at understanding their own emotions. The connection between "gut feelings" and actual gut sensing isn't a metaphor. It's neuroscience.

Your vestibular system — the fluid-filled canals in your inner ear — gives you balance. But it also does something weirder. Smith describes how on an airplane, during climb after takeoff, the cabin appears to tilt — the front looks higher than where you're sitting. Optically nothing has changed. But the fluid in your ear canals is telling your brain you're tilting backward, and that bleeds into your vision and reshapes what you see. You are literally seeing something that isn't happening because one sense is overruling another.

And that's the real revelation. These senses don't just coexist — they constantly interfere with each other. Smith's research group, working with Spence's Crossmodal Laboratory at Oxford, has been documenting this for over a decade, and the findings are wild. They discovered that changing the sound of your own footsteps makes you feel lighter or heavier. In the experiment, researchers boosted the high frequencies in the sound of participants' steps as they walked. The walkers reported feeling thinner, lighter, more energetic. Their gait actually changed — shorter heel strike, more dynamic swing. The sound of their footsteps literally altered their body image, in real time, through their ears. They found that aircraft noise kills your ability to taste sweet, salty, and sour — but leaves umami completely untouched. Tomatoes are packed with umami. That's why tomato juice tastes weirdly good on a plane when you'd never order it on the ground. It's not a quirk of altitude or air pressure. It's your ears sabotaging your tongue while leaving one flavor channel wide open.

They showed that the smell of rose in shampoo makes your hair feel silkier to the touch — same formula, same physical texture, different fragrance, different tactile experience. And that adding certain odors to low-fat yogurt makes it feel richer and thicker on your palate without changing a single ingredient. And then there are the senses that get genuinely unsettling when they break. The sense of agency — the feeling that you are the one moving your own body — can vanish in stroke patients. Smith describes people who watch their arm move and believe someone else is doing it. Closely related is the sense of ownership — the feeling that your body parts belong to you. Some stroke patients can still feel sensation in their arm but are completely convinced the arm is not theirs. Same nerve signals arriving in the brain. But the ownership tag is gone. Imagine looking at your own hand and feeling nothing — no recognition, no belonging. The arm is there. You can feel someone touch it. But it doesn't feel like yours.

The honest answer to "how many senses do humans have" is that nobody knows for sure. Is the sense of effort — the internal calibration for how much force is needed to lift a cup — its own sense or a sub-process of proprioception? Is your sense of time passing a sense or a cognitive function? The ambiguity is part of what makes this interesting, and it's what philosophers, neuroscientists, and psychologists are actively arguing about at places like the Centre for the Study of the Senses in London. But the number matters less than what it means for your daily experience. For the rest of today, you're going to notice things. The stiffness in your shoulders — interoception. Reaching for something without looking — proprioception. Eating dinner and catching yourself paying attention to how much of the flavor is coming from smell versus taste. The five senses aren't wrong — they're just an embarrassingly incomplete draft. Aristotle gave us the table of contents. We're still writing the book. From how we sense the world to how we got here in the first place. For decades, the going theory on the origin of life's building blocks had a warm, comfortable setting. Amino acids — the molecules that link together to form every protein in your body — were thought to form in liquid water. Warm, mildly acidic, chemically rich liquid water. The "primordial soup" narrative. You've probably seen the image in a textbook somewhere — volcanic vents, hot springs, a warm little pond where the right ingredients bumped into each other and life got started. A paper published last week in the Proceedings of the National Academy of Sciences, led by researchers at Penn State, says at least some of that story is wrong — and wrong in an interesting direction.

The team analyzed amino acids found in dust from the asteroid Bennu, those four-point-six-billion-year-old samples that NASA's OSIRIS-REx mission brought back to Earth in twenty twenty-three. They focused on glycine, the simplest amino acid, and measured its isotopes — tiny differences in atomic mass that work like chemical fingerprints, revealing how and where a molecule was made. The isotopic pattern they found didn't match Strecker synthesis, the standard warm-water process scientists had assumed was responsible. Instead, the data pointed to formation in frozen ice, bombarded by radiation in the cold outer reaches of the early solar system. To make sure this wasn't just a Bennu quirk, they compared their results to the Murchison meteorite — a famous space rock that landed in Australia in nineteen sixty-nine and has been the reference sample for cosmic organic chemistry ever since. Murchison's amino acids looked exactly like what you'd expect from warm water formation. Bennu's looked completely different. Two parent bodies, two chemically distinct regions of the solar system, producing the same building blocks of life through entirely different pathways.

The implications land in a specific place. If amino acids can form in frozen, irradiated ice and not just in warm ponds, then the conditions for life's raw ingredients aren't rare. They're everywhere. Every icy body in the outer solar system, every comet trailing through the dark, could be carrying the same molecular toolkit that eventually produced us. The universe isn't just capable of making life's ingredients — it apparently has multiple recipes. Lead researcher Allison Baczynski put it simply: life's building blocks can form in a diversity of environments throughout the universe. Not just the warm, wet, comfortable places. The cold, harsh, radioactive ones too. Two stories today that are really the same story. We thought we understood our own bodies — five senses, clean and simple. We thought we understood the origin of life — warm water, primordial soup. Both turn out to be first drafts. The real version is more complicated, more interesting, and still being written. Which, on a day when we celebrate how people make us feel, seems like a good thing to sit with. Love isn't just a 'feeling'—it's your interoception picking up a heart rate that isn't yours, and your proprioception finding comfort in the space someone else occupies. You contain more than you were taught. Stay informed, stay curious, and we'll see you tomorrow