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Why Is Spicy Food Spicy?

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Kids ask a lot of questions. mental_floss has answers. This week we launched WHY?, our new series for kids and parents. We'll tackle all types of questions children have about how the world works by providing science-based, kid-friendly content. Our answers are written with early readers (ages 4 to 7) in mind, but we think they're interesting—and educational—for everyone.

Have a question? Send it to why@mentalfloss.com.

That tingling, hot feeling usually comes from chili peppers, but sometimes from horseradish (a root) or mustard. Let’s talk about peppers. Their seeds have capsaicin (cap-SAY-uh-sin), which is an irritant to us. We feel this irritation like a burn. 

Pepper plants are trying to protect themselves—and make more pepper plants. Peppers are the juicy fruit of a flowering plant. Birds and animals eat the peppers and then poop out the seeds. That’s good! The seeds then grow in a new place. But when bugs eat the peppers, they leave little holes in the fruit. Tiny creatures called fungi (FUN-guy) enter the holes and eat the seeds, stopping them from growing. Capsaicin protects the seeds from the fungi. 

A lot of people think a little burn makes food taste better. But a lot of others don’t. Eating food that’s too spicy for you can hurt your mouth and your stomach. So it’s important to know your peppers before you eat. The Scoville Scale orders chili peppers from hottest to mildest. The hottest peppers can be more than 2 million times spicier than the mildest. Now that’s hot! 

To learn more, listen to NPR's interview with the biologist who discovered the connection between pepper heat and fungi.

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iStock/Chloe Effron
Why Do I Get Cavities?
iStock/Chloe Effron
iStock/Chloe Effron

WHY? is our attempt to answer all the questions every little kid asks. Do you have a question? Send it to why@mentalfloss.com.

Your mouth is a busy place. There are hundreds of different kinds of bacteria living on your teeth, tongue and gums. Bacteria, as you may know, are tiny little critters that can only be seen with a microscope. We need some of them to help keep us healthy. Others are more of a pain—especially when they cause cavities (CAA-vih-teez), or little holes in our teeth. If you get a cavity, a dentist will have to treat it. You may get a filling.

During the day, you put all kinds of food into your mouth. When you eat, the bacteria that live in there eat, too. Some bacteria make acid out of the sugar in food. So when you eat sweet stuff—candy, cookies, and sugary drinks—you are helping bacteria to make more acid. The acid eats through the enamel, or the hard coating on your teeth. Over time, this can cause cavities and infections. Ouch! Luckily your spit, or saliva (suh-LIE-vuh), has minerals in it, like calcium and phosphate, that fight back by making your tooth enamel stronger and cutting down on acid. The fluoride in toothpaste helps do this, too. If you have a cavity, a dentist can fill the hole to keep bacteria from getting in and causing a bad infection. Unfortunately, there’s another reason for cavities that you don’t control: genes (jeenz).

Genes are little codes inside our cells that get passed down from our parents. They are instructions to our bodies that affect how we look, act, and grow. Genes may play a big part in whether we get cavities. Some people end up with cavities because of their genes, even if they take really good care of their teeth. Other people hardly get any. We can’t change our genes, but we can control other things. Brushing your teeth, visiting the dentist, and avoiding sweets can all help you keep cavities away.

Want to find out more about what lives inside your mouth? Watch the cartoon below from the National Institutes of Health.

 

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iStock/Chloe Effron
Why Do Lizards Lose Their Tails and Regrow New Ones?
iStock/Chloe Effron
iStock/Chloe Effron

WHY? is our attempt to answer all the questions every little kid asks. Do you have a question? Send it to why@mentalfloss.com.

Many species of lizard lose their tails when they are being chased. When a predator (PREH-duh-tor)—an animal that wants to eat them, like a bird or cat—grabs for the tail, it falls off, and the lizard can run away. How does it happen? Scientists looking at geckos (a type of lizard) under a microscope have found out that some parts of the tail are weaker than other parts.

It’s no accident. The sections of a lizard’s tail will hold together until the lizard is in danger. Scientists think that’s when special cells inside the tail make chemicals that attack the weak points. Then—surprise!—the tail breaks off. It will also keep wiggling for a while to distract the predator while the lizard speeds off. Pretty awesome! That’s not the end of the story, either. Most lizard species can also grow a new tail. 

Lizard tails have a lot of jobs to do. Lizards move their tails around to “talk” to each other. It’s a kind of secret lizard language. The tail also helps lizards keep their balance when they’re scrambling up a tree or jumping from rock to rock. So even though losing the tail is a useful trick, growing it back is pretty important, too. Sometimes lizards can get carried away, though: one busy lizard from Argentina grew six new tails at once!

Watch a gecko regrow its tail in this video

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