Why Do We Bite Our Nails?

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iStock

It can happen anywhere. Maybe you're waiting in the lobby of your doctor's office or studying at home for a big test—and then, without you even registering it, your fingertips are in your mouth and your teeth are gnawing away.

Even the people who do it tend to see nail biting as a nasty habit, but that doesn't make it any less prevalent. Twenty to 30 percent of people admit to biting their nails on a regular basis. Though reasons for the behavior vary, research has shown that most people do it because they need a psychological crutch, and not because they like having dirty, ragged fingernails.

According to Kieron O'Connor, a researcher at the University Institute of Mental Health at Montreal, there’s no one mood associated with nail biting. “People think you only bite when you’re stressed, but it’s not so simple,” O'Connor tells Mental Floss. “People will also bite when they’re bored and alone.” Nail biting feels good (in moderation at least), so when some people have nothing to do, or want to avoid the task in front of them, they bring their nails to their mouth out of habit. This same thing happens when nail biters feel overwhelmed by a stressful situation, or when they’re ruminating over some past behavior they feel embarrassed about. In all cases, nail biting is used as a mood regulator: a tool that distracts them or provides temporary relief or stimulation whenever an unwanted feeling comes up.

A study co-authored by O’Connor found that nail biting is more common in perfectionists. After speaking with 48 subjects, half with habit disorders like nail biting and half without, they found that the nail biters tended to be organizational perfectionists, or people who tend to over-plan, work too much, and become restless when they don’t have enough to do. “When people are perfectionists, they get bored and frustrated very easily and hold themselves to higher standards,” O’Connor says. “They plan too much, and when they can’t do all of it they have a sense of failure.”

So what is it about nail biting specifically that makes some people turn to the behavior when they’re feeling less than fantastic? Like many of our worst habits, nail biting is an evolutionary adaptation kicked into overdrive. Even before we had access to aisles worth of beauty products, humans practiced self-grooming, which includes getting rid of the occasional hangnails. But even nail biters with short, clean nails will engage in the behavior: They use it as a way to get the mental reward our brains associate with grooming without any of the cosmetic benefits.

Nail biting manifests itself at different levels of intensity. At one extreme there’s onychophagia, a condition where compulsive nail biting requires medical attention. Like skin picking and hair pulling, nail biting can be a symptom of a body-focused habit disorder. When it gets to the point that someone is harming themselves by chewing their nails so often, they usually require a mental health professional to help them curtail the behavior.

But for far more people, nail biting is just an annoying habit that’s hard for them to quit—no matter how much the squeamish people around them wish they would.

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Why Do Babies Learn to Crawl Before They Walk?

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iStock/ozgurdonmaz

Fabian van den Berg:

Babies walk or dance before they crawl actually, well sort of, you’ll see.

Babies are amazing little creatures. They are very different from adults and should be treated as such. They aren’t born as blank slates, though; a lot of things are innate, and a lot of things are learned. And boy can they learn—not just by watching others do things, but also by experimenting. There’s a reason why early developmental psychologists called them "little scientists." They will form strategies on their own, test them out, and choose the best one.

We’ll focus on walking for now.

Newborns come fully equipped with a stepping reflex. If you happen to have a newborn at your disposal you can try it out (but support the head). By dragging them a bit over a surface, the feeling of their feet/soles touching will initiate a stepping reflex, it looks like they’re walking. (Don’t let go though, they are definitely not ready to stand on their own yet and will fall down.)

The reflex tends to be present for the first two months, sometimes returning right before they start to walk. It’s thought that the reflex helps to train the muscles and motor nerves. The reason why it disappears is thought to be because the legs become too heavy, the muscles grow faster than their strength. Basically, they become too chubby and the reflex doesn’t work anymore.

In a way, they are born with the ability to walk or dance (it differs a bit from baby to baby), but then lose it again because they grow so fast.

There are a lot more interesting and fun baby reflexes, like swimming and grasping, but that’s for another answer.

That brings us to toddlers and locomotion: Many parents will attest they looked forward to their baby being able to move on their own, and as soon as they did they missed the times the little bugger would stay put.

Infants can be very motivated, which is where the little scientist pops up. Having toys or anything interesting looking sitting around is very tempting. Kids love touching things, they explore, and they really want to go there… But how…

Should they wait for the big person to either bring them there or bring the shiny to them? No, of course not. They can move now—so off they go!

They will experiment and explore a lot of different ways of getting around. A very popular one is scooting. They are laying there (they’re good at that), but they want to be elsewhere. Almost all children will solve this conundrum by pulling or pushing themselves using their hands [and] scooting or shuffling across the floor. A popular and funny variation is scooting on their bums. If they can sit, they’ll prefer to sit and just use their arms and legs to push themselves around.

It’s not uncommon for children to be in this stage until they learn how to walk. It really is a matter of what works best for them.

Crawling is merely a more advanced version of scooting. Their legs become stronger and they are able to control them better. They will happen upon crawling by trial and error, and find that it can bring them from Point A to Point B faster than scooting.

The logic is simple to follow: I want to go over there, crawling works best, so crawling it is.

Strategy use is very common in children, you see it in many aspects. They will try out new things, compare it to old things, and decide on whatever works best. In the case of crawling it’s mostly about speed. But as I said before, not all kids crawl. For some scooting works best, and they’ll use it until they learn how to walk.

It’s also not strange to see them use different strategies, sometimes crawling, sometimes scooting. Usually this occurs when they are learning and experimenting with new strategies.

Children don’t need examples to learn, they are very capable on their own. They will try and discover things like the small scientists they are.

Crawling is one of those things. They don’t need to see it, they discover it, realize it works better than what they had before, and start using it more and more until something better (like walking) comes along.

This post originally appeared on Quora. Click here to view.

Why Do Hangovers Get Worse As You Get Older?

iStock/OcusFocus
iStock/OcusFocus

“I just can’t drink like I used to” is a common refrain among people pushing 30 and beyond. This is roughly the age when it starts getting harder to bounce back from a night of partying, and unfortunately, it keeps getting harder from there on out.

Even if you were the keg flip king or queen in college, consuming the same amount of beer at 29 that you consumed at 21 will likely have you guzzling Gatorade in bed the next day. It’s true that hangovers tend to worsen with age, and it’s not just because you have a lower alcohol tolerance from going out less. Age affects your body in various ways, and the way you process alcohol is one of them.

Because your body interprets alcohol as poison, your liver steps in to convert it into different chemicals that are easier to break down and eliminate from your body. As you get older, though, your liver produces less of the enzymes and antioxidants that help metabolize alcohol, according to a study from South Korea. One of these enzymes—called alcohol dehydrogenase (ADH)— has been called the “primary defense” against alcohol. It kicks off the multi-step process of alcohol metabolization by turning the beer or booze—or whatever you imbibed—into a chemical compound called acetaldehyde. Ironically, this substance is even more toxic than your tipple of choice, and a build-up of acetaldehyde can cause nausea, palpitations, and face flushing. It usually isn’t left in this state for long, though.

Another enzyme called aldehyde dehydrogenase (ALDH) helps convert the bad toxin into a new substance called acetate, which is a little like vinegar. Lastly, it’s converted into carbon dioxide or water and expelled from your body. You’ve probably heard the one-drink-per-hour recommendation, which is roughly how long it takes for your liver to complete this whole process.

So what does this mean for occasional drinkers whose mid-20s have come and gone? To summarize: As your liver enzymes diminish with age, your body becomes less efficient at metabolizing alcohol. The alcohol lingers longer in your body, leading to prolonged hangover symptoms like headaches and nausea.

This phenomenon can also partly be explained by the fact that our bodies tend to lose muscle and water over time. People with more body fat don’t break down alcohol as well, and less water in your body means that the booze stays concentrated in your system longer, The Cut reports. This is one of the reasons why women, who tend to have a higher body fat percentage than men, often suffer worse hangovers than their male counterparts. (Additionally, women have fewer ADH enzymes.)

More depressingly, as you get older, your immune system deteriorates through a process called immunosenescence. This means that recovering from anything—hangovers included—is more challenging with age. "When we get older, our whole recovery process for everything we do is harder, longer, and slower," gastroenterologist Mark Welton told Men’s Health.

This may seem like a buzzkill, but we're not telling you to put down the pint. However, if you're going to drink, just be aware of your body’s limitations. Shots of cotton candy-flavored vodka were a bad idea in college, and they’re an especially bad idea now. Trust us.

Have you got a Big Question you'd like us to answer? If so, let us know by emailing us at bigquestions@mentalfloss.com.

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