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Why Are Some Farts Noisy?

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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.

Farts can make a lot of different noises. Some farts are high and squeaky. Some explode like a machine gun. Some don’t make any noise at all. It all depends on how much gas you have in your intestines and on the muscles around the anus (the opening in your butt).

Farts happen when your body lets out gases. Some of that gas comes from air that you swallow as you are eating and breathing. Some of it is made as your body digests, or breaks down, food to turn it into energy. Millions of tiny organisms called bacteria living in your gut help with digestion too. As they do, different gases get released. Those gases move along through your large intestine until they reach its end, called the rectum. Then they come out as farts: some quiet, some loud enough to rattle the windows!

The sound of your farts is affected by how much gas has built up inside, and how fast it comes out. It also depends on how tight the sphincter (SFINK-ter) muscles are. They ring the anus and help keep it closed. All these things together cause vibrations as the gas pushes through. If the sphincter is relaxed, your fart will probably be on the quieter side—pffft! But if those muscles are tightened up (as they are when you are trying not to fart), you’re probably going to squeak, toot, rumble, or roar. 

To learn more about gut bacteria, farts, and sharing poop for health reasons, watch this video from MIT.


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Why Do I Get Cavities?
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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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Why Do Lizards Lose Their Tails and Regrow New Ones?
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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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