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.

 

A Team of Cigarette Butt-Collecting Birds Are Keeping a French Theme Park Litter-Free

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iStock

The six rooks pecking at litter within the Puy du Fou theme park in Les Epesses, France, aren't unwelcome pests: They're part of the staff. As AFP reports, the trained birds have been dispatched to clean up garbage and cigarettes butts from the park grounds.

Rooks are a member of the corvid family, a group of intelligent birds that also includes ravens and crows. At Puy du Fou, an educational amusement park with attractions inspired by various periods from French history, the rooks will flit around park, pick up any bits of litter that haven't been properly disposed of, and deliver them to a receptacle in exchange for a treat. At least that's how the system is set up to work: The full team of six rooks has only been on the job since August 13.

Employing birds as trash collectors may seem far-fetched, but the experiment has precedent. The Dutch startup Crowded Cities recently started training crows to gather cigarette butts using a vending machine-like device. Once the crows were taught to associate the rig with free peanuts, the machine was tweaked so that it only dispensed food when the crow nudged a cigarette butt resting on a ledge into the receptacle. The cigarette butts were eventually removed, and the birds figured out that they had to find the litter in the wild if they wanted to continue receiving their snacks.

Crowded Cities had planned to conduct more research on the method's effectiveness, as well as the potentially harmful effects of tobacco on crows, before bringing their vending machines to public spaces. Puy du Fou, meanwhile, has become one of the first—if not the first—businesses to fully implement the strategy on a major scale.

Even if it doesn't prove to be practical, Puy du Fou president Nicolas de Villiers told AFP that cleaning up the park is only part of the goal. He also hopes the birds will demonstrate that "nature itself can teach us to take care of the environment."

[h/t AFP]

Online Daters Tend to Be Interested in Partners 25 Percent More Desirable Than They Are

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iStock

Online dating may not bring out the best in people (as anyone who’s been ghosted can attest) but it does bring out our optimistic side. A new study suggests that people tend to reach out to fellow online daters who are approximately 25 percent more attractive than they are, according to The Washington Post.

The study, published in the journal Science Advances, looked at online dating messaging behavior from heterosexual men and women in four different U.S. cities. Researchers analyzed how many messages people sent and received in January 2014, how long those messages were, and how many messages went unanswered.

They examined daters in New York City, Chicago, Seattle, and Boston, including age, ethnicity, and education of the users in their analysis, but kept the profiles anonymous and did not read the messages themselves. (The researchers don’t name the particular site they got their data from, merely describing it as a “popular, free online dating service.” From the details, it sounds a lot like OkCupid or a very similar site: one that allows users to answer open-ended essay questions and list attributes like their religion and body type on their profiles.)

To quantify how desirable a person was, the researchers looked at the hard numbers—how many messages someone received, and how the senders themselves ranked on the desirability scale.

Both men and women tend to aim high, messaging someone more desirable than themselves by about 25 percent, on average. For the most part, users didn’t contact people who ranked lower than themselves on the desirability scale. When they did contact people who were hotter, daters tended to write much longer messages than they did when they contacted someone on their own level, so to speak—sometimes up to twice as long. Women tended to use more "positive" words (like "good" and "happy") when they were writing to hotter dudes, while men actually used fewer positive words when talking to hotter ladies. Men in Seattle sent the longest messages, perhaps because of the city’s makeup—in some populations, there are twice as many men there as women, so heterosexual men face a lot of competition. Although wordy messages in Seattle did have a slightly higher response rate, in other cities, the extra time spent typing out missives didn’t pay off. Given that those messages weren’t any likelier to get a response than a short note, the researchers write that the “effort put into writing longer or more positive messages may be wasted.”

The data also showed how desirability in online dating can be influenced by attributes like age, education level, and ethnicity. For instance, at least as far as averages go, older men tended to be viewed as more desirable than younger men until they hit 50. Women’s scores peaked when they were 18 years old (the youngest age when you can join the site) and decreased until age 60.

Even if you aren’t in the pool of the most attractive users, sometimes, aiming high can pay off. “Even though the response rate is low, our analysis shows that 21 percent of people who engage in this aspirational behavior do get replies from a mate who is out of their league, so perseverance pays off,” co-author Elizabeth Bruch explained in a press release.

[h/t The Washington Post]

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