Ever noticed that when you stare at your fingers for long enough they start transforming into alien appendages before your very eyes? You see the mundane for what it really is: freaky-looking.
The same goes for the rest of our traits. We take for granted that funny things make us yell out spastically also known as laughing and that we spend one-third of every day in a deathlike state of suspended animation known as sleep. But with a little contemplation, these behaviors seem truly bizarre.
Here are 15 mundane yet weird things we do all the time, and why we do them.
Contributing reporting by Ben Mauk, Corey Binns, Stephanie Pappas and Michelle Bryner.
Prefer one hand to another
Take another look at those hands of yours. You have two of them, correct? Then why is it that you tend to use just one of these appendages for so many tasks?
Whether you're a leftie or a righty, the fact that you have a dominant hand at all is a bit weird, according to scientists. After all, having two hands with excellent motor skills would be a real boon for humans.
One theory about why people have dominant hands has to do with the way the brain processes speech. The theory holds that the left brain hemisphere — where the speech center of most humans resides — is more intricately wired than the right brain hemisphere. The left brain hemisphere also happens to control the right side of the body. It's possible that the extra wiring in this part of the brain is behind the dominance of the right side of the body in right-handed people.
However, researchers have found that not all righties have speech centers residing in the left brain hemisphere. In other words, this theory might not be correct. However, there are lots of other theories that could help explain human handedness.
Here's a lesson you've probably learned on plenty of occasions: People lie. We do it for many reasons (some malicious and others completely benign), but everybody lies sometimes. And we'd be lying if we said we knew why.
The truth is that scientists aren't sure why humans tell lies, but they do know that lying is common and that it is likely linked to several psychological factors. Foremost among these factors is self-esteem, according to Robert Feldman, a psychologist at the University of Massachusetts. Feldman, who studies the underlying causes of human deceit, has found that when a person's self-esteem is threatened, he or she will "immediately begin to lie at higher levels."
"We're trying not so much to impress other people but to maintain a view of ourselves that is consistent with the way they would like us to be," Feldman told Live Science in 2006. In other words, people often lie to make social situations easier. This might mean telling a lie to avoid hurting someone else's feelings or to avoid a disagreement.
But bald-face lies (i.e. making something up or falsifying information) often occur when people are trying to avoid punishment or embarrassment, according to William Earnest, an assistant professor of communication at St. Edward's University in Austin, Texas, and co-author of the book "Lying and Deception in Human Interaction (opens in new tab)" (Pearson, 2007).
Alter our bodies
In 2015, Americans spent more than $13.5 billion on surgical and nonsurgical aesthetic procedures, according to the American Society for Aesthetic Plastic Surgery. That's a lot of nipping and tucking.
Why do humans feel the need to alter their bodies with surgeries or permanent ornamentations, like tattoos and piercings? Scientists think the answer is pretty simple: People think plastic surgery and other cosmetic procedures will make them look better and therefore, feel better.
"There's this idea that if you look better you'll be happier. You'll feel better about yourself," said psychologist Diana Zuckerman, president of the National Research Center for Women & Families. "And logically that makes so much sense, because we live in a society where people do care what you look like."
However, some bodily alterations — specifically plastic surgery — don't necessarily make you appear more attractive to others, according to a study published in the journal JAMA Facial Plastic Surgery in 2013.
If you're like most humans, then you've probably been on at least one end of the grapevine a few times. Like it or not, gossip is a part of everyday life. In fact, scientists speculate that gossip may actually bring us humans closer together.
Robin Dunbar, a primatologist at Oxford University in the United Kingdom, likens gossip to the constant grooming of other primates. Baboons pick bugs out of each other's back hair; we humans talk about others behind their backs. It's the verbal glue that keeps our social bonds strong, according to Dunbar.
Other researchers, such as Jennifer Bosson, a professor of psychology at the University of South Florida, agree that sharing our dislikes of others helps develop a bond between the gossiper and the listener.
"When two people share a dislike of another person, it brings them closer," Bosson told Live Sciencein 2006.
Have brain farts
Forgetting tidbits of information isn't weird at all, but forgetting facts that you really ought to know — like why you just walked into a room or the name of your own child — is definitely a little odd. Yet, these so-called brain farts occur rather frequently for us humans.
Lots of things can cause your memory to lag, according to researchers. Some of the most common culprits are stress and sleep deprivation. But you don't have to be going through a rough patch to forget important stuff; something as simple as opening a door can trigger a brain fart, according to a study published in the Quarterly Journal of Experimental Psychology in 2011.
And lots of other random things can also cause your brain to experience tiny blips in memory recall, including spinning tires and shadows. [10 Everyday Things That Cause Brain Farts]
Everybody gets bored sometimes. But, if you really think about it, feelings of boredom are pretty strange. After all, there's a whole wide world full of stuff to do. How could humans ever lack for something to keep us occupied?
It turns out that boredom isn't really about keeping busy. Boredom stems from an objective lack of neurological excitement, which brings about a subjective psychological state of dissatisfaction, frustration or disinterest, according to researchers who study this yawn-inducing subject.
And some people are more prone to boredom than others. People who have conditions that affect their ability to pay attention (like ADHD) might be more susceptible to boredom, according to a study published in the journal Perspectives on Psychological Science in 2012. Age might also play a role in determining someone's susceptibility to boredom. Researchers have found that people nearing the end of their young adulthood, around age 22, may be less likely than teenagers to get bored.
"In that age range, the frontal cortex is in the final stages of maturation," and this part of the brain helps with self-control and self-regulation," James Danckert, professor of cognitive neuroscience at the University of Waterloo in Ontario, told Live Science in September 2016.
Think about dying
Ever think about dying? If you answered "no" to that question, then you're not like most folks, for whom thoughts of death and dying are "very common and very natural," according to Pelin Kesebir, an assistant scientist and psychologist at the Center for Healthy Minds at the University of Wisconsin-Madison.
While obsessing over one's own mortality isn't necessarily normal, us humans do tend to think of our own demise (or that of loved ones) from time to time. People might think about death a lot because of our sophisticated brains, Kesebir told Live Science in September 2016. Our minds "make us painfully aware of inevitable mortality, and this awareness clashes with our biologically wired desire for life," she said.
This morbid pondering causes anxiety for some, while for others it can be a source of "immense clarity and wisdom," she added.
While many Americans nowadays are opting out of organized religion, billions of people around the world practice the world's major religions, which include Christianity, Islam and Hinduism.
But where did religion come from in the first place? While each faith has its own origin story, the story behind how religious thought first cropped up in humans can also be explained by science. One of the most popular religious origin theories has to do with what researchers call the "god faculty."
Early humans lived in a world in which they had to make quick decisions to avoid peril — the ones who sat around wondering whether that sound they heard behind them was a lion or just the wind in the grass were quickly dispatched. Early peoples that survived to procreate had developed what evolutionary scientists call a hypersensitive agency-detecting device, or HADD, according to Kelly James Clark, a senior research fellow at the Kaufman Interfaith Institute at Grand Valley State University in Michigan.
But HADD didn't just help people avoid encounters with hungry lions, it also may have planted the seeds of religious thought, by reinforcing the idea that outside forces have agency, or the ability to act of their own accord, Clark told Live Science in 2015.
Do stuff that's bad for us
Smoking cigarettes, drinking heavily, using drugs — all of these things are bad for us, and yet, setting these self-destructive behaviors aside can be a real chore. Why is it so hard for humans to ditch their bad habits? Scientists list several reasons for why we don't always know what we know is good for us.
Aside from a genetic predisposition for certain addictive habits, some people might engage in risky behavior, like using drugs or alcohol, because they're not really thinking through the consequences of these actions, according to Cindy Jardine, a professor in the School of Public Health at the University of Alberta, in Canada.
"But it's not because they haven't gotten the information that these are big risks. We tend to sort of live for now and into the limited future — not the long term," Jardine told Live Science in 2008.
How odd that sadness causes water to spill from our eyes! Among all animals, we alone cry tears of emotion.
Not only do they serve the purpose of communicating feelings of distress, scientists believe tears also carry certain undesirable hormones and other proteins that are produced during periods of stress out of the body, which may explain the cathartic effect of "a good cry."