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The Debunker: Do People Have Five Senses?

by Ken Jennings

In addition to his day job as Woot's full-time "Debunker," Jeopardy! wunderkind Ken Jennings moonlights as an author of books, and this month he has a new one in stores. It's the fifth in his Junior Genius series, this time chock-full of amazing facts about The Human Body. To mark the occasion, he'll spend all of February debunking anatomical anachronisms and medical misinformation for us. Finally: the inside scoop about our own insides.

The Debunker: Do People Have Five Senses?

"There is no sixth sense in addition to the five enumerated: sight, hearing, smell, taste, touch," wrote Aristotle in his landmark work De Anima, or On the Soul. And for the next two thousand years, Western civilization stuck with this view: five senses, period. "Sixth sense" became shorthand for some rare, ephemeral, unclassifiable-by-science gift, like telepathy.

the senses

I don't want to get too down on Aristotle, because he was obviously a pretty bright guy. But if you read further into De Anima, you realize that some of his theories about the mind haven't held up so well. There must be five senses, he says, because there are five elements in nature: earth, air, fire, water, and "aether." Our sense organs are actually based on different combinations of these elements. The eye is made of water, for example, while the ear is clearly air-based. It's all a little nutty from a modern perspective.

Ask a modern physiologist, someone not so wrapped up in ancient Greek traditions, how many senses human beings have, and you'll get a very different answer, as high as twenty or so. Sure, there are the five O.G. senses: sight, hearing, smell, taste, touch. But it turns out that the brain has separate sensors for many other kinds of sensory input. Pressure and temperature are distinct from touch, it turns out. Pain and itch are processed in different places. There's your sense of balance, which you've probably noticed, and a mild sensitivity to magnetic fields, which you probably haven't. Some of your twenty-one senses are even more abstract, Zen-sounding ones like proprioception (your internal handle on where your own body parts are located) and chronoception (your awareness of the passage of time). That's right: that sudden, sinking realization that Britney's first album came out over fifteen years ago is your chronoception letting you down. Aristotle had no idea.

Quick Quiz: In the movie The Sixth Sense, what former singer plays the character who (SPOILERS!) kills Bruce Willis in the movie's opening scene?

Ken Jennings is the author of six books, most recently his Junior Genius Guides, Because I Said So!, and Maphead. He's also the proud owner of an underwhelming Bag o' Crap. Follow him at ken-jennings.com or on Twitter as @KenJennings.