Breathing, eating, kissing, cursing out idiot motorists who forget to use their turn signals: all of these essential processes would be very difficult without our mouths.
And though we use it all the time, we don’t often think about what goes into making it work. The mouth is a busy thoroughfare, where the respiratory system meets the digestive system meets the nervous system meets our need to yell profanities out the window going sixty miles an hour, and it’s a complex feat of biological engineering that we can manage them at the same time.
From hidden teeth to medieval kissing, from thin skin to assisted digestion, the mysteries of the mouth are manifold (whew! try saying that one three times fast). Here are fifteen jaw-dropping facts to start off with!
1. Read My Lips: Why are the lips a different color from the rest of the face? While typical facial skin has 16 layers, the skin on the lips only has three. In light-skinned people, the area has fewer melanocytes, giving the lips their distinctive pink color from the blood vessels underneath the skin.
2. H2Oh!: Water may have no taste, but we need it to be able to taste anything. Our taste buds are able to pick up chemicals like salt and sugar because they’re dissolved in our saliva. Much like kissing, if you try to go into eating with a dry mouth, you’re not going to have a lot of fun.
3. Speaking in Tongues: The French kiss got its English name at the turn of the 20th century when the comparatively-reserved English saw France as a cesspool of licentious sexual practices. But the French word for the practice changed in 2013, when The Petit Robert 2014 French dictionary added the verb “se galocher,” to kiss with tongue. Before then, it was called un baiser amoureux (“a lover’s kiss”) or un baiser avec la langue (“a kiss with the tongue”).
4. Kiss of Death: If you ever find yourself at the scene of a crime, don’t lick anything. Much like fingerprints, tongue prints are unique. Better not kiss anything either; lip prints are thought to be idiosyncratic as well.
5. Chew on This: Digestion actually starts in the mouth! Mechanical digestion (physically breaking the food into smaller pieces) starts with chewing, and chemical digestion (breakdown of molecules with chemicals) starts with salivary amylase, which breaks down carbs into simpler sugars.
6. Down The Rabbit Hole: Yes, when you choke on food, it might actually be going down the wrong pipe. When you’re swallowing food, the epiglottis closes over the windpipe like a trapdoor to stop food from going into your respiratory system. But the system isn’t foolproof, especially when you’re swallowing liquids, which move faster and are harder to manage.
7. X marks the spot: The X’s and O’s on the bottom of love letters have their origins in actual kisses. In Medieval Europe, many people could not read or write, so they signed documents with an X and then kissed it to show their sincerity.
8. Tasty: The tongue isn’t the only part of the body where you can find taste buds. Of the approximately 10,000 taste buds in our mouth, 8,000 of them are on the tongue and the rest are on the cheeks, lips, the roof of our mouth and under our tongues.
9. Hold Your Tongue: While the tongue isn’t the strongest muscle in the body, it’s one of the strangest. It’s actually made up of eight muscles, four intrinsic muscles which change the tongue’s shape and four extrinsic muscles which change its position. The extrinsic muscles are attached to bone at one end, but the intrinsic muscles are the only ones in the body that aren’t directly anchored to bone.
10. Kiss and Tell: A study entitled “Examining the Possible Functions of Kissing in Romantic Relationships” didn’t find much evidence that the primary purpose of kissing was getting the two partners aroused. Instead, they found that kissing is a “mate assessment test,” where people, especially women, figure out if a potential mate is worth their while.
12. Pearls of Wisdom: Back in our evolutionary past, when we foraged for tough foods like nuts and roots, wisdom teeth were a necessary aid to grinding these foods up. Today, when we forage for processed foods in our cupboards, wisdom teeth are mostly useful for getting people to say stupid things under dental anesthetic.
13. A Delicate Touch: The neurons that represent our sense of touch occur in the brain’s postcentral gyrus, and specific areas in the gyrus correspond to the sense of touch in specific body parts. The lips (along with the fingers) have the disproportionately-largest areas, making them more sensitive than almost anywhere else in the body
14. Hidden Depths: Much like an iceberg, a significant portion of your tooth is hidden below the surface. An entire third of your teeth hide under the gumline, and because teeth are the most unnecessarily weird and ominous part of the human body, it’s called the root.
15. Another One Bites The Dust: Teeth are living, hosting their own nerve endings and blood supply, which means that they can also die (and it’s exactly as unpleasant as it sounds). Also, even though the enamel protecting them is the strongest material in the human body, it’s also the only tissue that can’t regenerate, and … you know what, I think I’ve had enough tooth facts for today. Also, the rest of my life.