All of Your Teeth Evolved From a Single Ancestral Tooth in the Age of the Dinosaurs

iStock
iStock

Anyone who's received a root canal or a lecture from their dentist about flossing probably doesn't appreciate their teeth like they should. But our pearly whites are unlike any other structures in the body, and for that, they deserve some recognition.

In their new video, TED-Ed explains what exactly makes teeth unique. Unlike regular bones, teeth are made of two layers: a hard enamel coating and a strong dentin core. The combination of these two components makes teeth both hard and strong enough to endure a lifetime of wear and tear.

The tooth's tough composition isn't exclusive to humans. All mammals, whether they're meat-tearing cats or grass-munching cows, grow their teeth the same way, and they owe their teeth's existence to a common ancestor.

In the 19th century, paleontologist Edward Drinker Cope hypothesized that the tribosphenic molar, a tooth type that evolved during the dinosaur age, is the root of all modern mammalian teeth. With just a few genetic tweaks made over millennia, the tribosphenic molar has given way to the teeth used by carnivores, herbivores, and omnivores to process their food.

To learn more about the evolution and biology of teeth, check out the video from TED-Ed below.

[h/t TED-Ed]

Why Is Pee Yellow?

Chloe Effron
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 body is kind of like a house. You bring things into your body by eating, drinking, and breathing. But just like the things we bring home to real houses, we don’t need every part of what we take in. So there are leftovers, or garbage. And if you let garbage sit around in your house or your body for too long, it gets gross and can make you sick. Your body takes out the garbage by peeing and pooping. These two things are part of your body’s excretory system (ECKS-krih-tore-eee SISS-tem), which is just a fancy way of saying “trash removal.” If your body is healthy, when you look in the toilet you should see brown poop and yellow pee.

Clear, light yellow pee is a sign that your excretory system and the rest of your body are working right. If your pee, or urine (YER-inn), is not see-through, that might mean you are sick. Dark yellow urine usually means that you aren’t drinking enough water. On the other hand, really pale or colorless pee can mean you might be drinking too much water! 

Your blood is filtered through two small organs called kidneys (KID-knees). Remember the garbage we talked about earlier? The chemicals called toxins (TOCK-sins) are like garbage in your blood. Your kidneys act like a net, catching the toxins and other leftovers and turning them into pee.

One part of your blood is called hemoglobin (HEE-moh-gloh-bin). This is what makes your blood red. Hemoglobin goes through a lot of changes as it passes through your body. When it reaches your kidneys, it turns yellow thanks to a chemical called urobilin (yer-ah-BY-lin). Urobilin is kind of like food coloring. The more water you add, the lighter it will be. That's why, if you see dark yellow pee in the toilet, it's time to ask your mom or dad for a cup of water. 

To learn more about pee, check out this article from Kids Health. 

Flashing Status Symbols Won’t Impress New Friends—and May Even Backfire

iStock
iStock

Trying to keep up with the Joneses isn’t a very effective way of making friends. As The Outline reports, a recent study in the journal Social Psychological and Personality Science suggests that flashing status symbols makes people less likely to want to be your friend.

While some may feel like sporting a luxury watch or designer clothes will draw people toward them, it actually does the opposite, making you a less attractive potential friend, according to a trio of researchers from Michigan, Singapore, and Israel. Over the course of six different experiments, the researchers found that study participants tended to think that high-status markers like fancy cars would help them make new friends. The trend stayed true across both participants recruited using Amazon Mechanical Turk and upscale shoppers stopped for a survey in a high-income suburb.

People thought that showing up to an outdoor wedding in a luxury car or going out to a downtown bar wearing a fancy brand-name watch would lead people to be more attracted to them as potential friends, compared to someone driving a basic car or wearing a generic watch. Yet participants also rated themselves as being more willing to befriend someone with generic clothes and cars than someone who flashed designer goods.

The paradox makes a little more sense if you go back to the idea of “keeping up” with our neighbors. People want to look high status in comparison to others. They don’t want to hang out with people who are flashing around luxury goods—they want to be the flashier ones.

[h/t The Outline]

SECTIONS

arrow
LIVE SMARTER
More from mental floss studios