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Why Do I Get Cavities?

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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.

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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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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istock/Chloe Effron
Why Are Flamingos Pink?
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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.

It’s easy to spot flamingos. These amazing birds have long, skinny legs and a long, skinny neck to match. When they first hatch, flamingos have pale gray feathers. As they grow up, their feathers start to turn beautiful shades of pink.

It’s because of what they eat. Flamingos hang out in big flocks in wetlands like shallow lakes and lagoons. They stand high and dry on their long legs and swish water through their big beaks to catch bits of food. What do flamingos like to eat? One thing is algae (AL-jee), a type of water plant. They also love tiny crustaceans (cruss-TAY-shuns)—animals like shrimp with hard shells or skeletons on the outside. These are the foods that turn flamingos pink. 

Just like the carrots, pumpkins, and tomatoes that humans eat, algae and many crustaceans contain natural chemicals with a red-orange pigment, or color. As baby flamingos digest algae and shrimp, these healthy chemicals get stored in their fat. The fat helps their feathers grow. Over time, this turns their feathers different shades of pink, orange, and sometimes even red. If flamingos stop eating the foods that turn them pink, their color fades!

Watch this video with David Attenborough to learn why a pink bird is a healthy bird! 

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