20 Obvious Things Confirmed by Science

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Brace yourself—these are shocking developments.

1. YOUR CAT IS IGNORING YOU.

A woman kissing a fluffy calico cat that is looking off to the side.
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Your tabby recognizes the sound of your voice, but it’s ignoring you anyway. A recent study at the University of Tokyo showed that, although a cat can identify its owner’s voice, it really doesn’t care enough to listen. The reason for kitty’s cold shoulder? Evolution. Unlike dogs, which were bred and domesticated by humans, cats domesticated themselves. They just aren’t hardwired to listen for commands.

2. STUDENTS WHO DO HOMEWORK GET HIGHER GRADES.

Young Boy In Bedroom Sitting At Desk Doing Homework
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Economist Nick Rupp divided his class into two groups—those required to do homework, and those who were not. The results were (not) shocking. Kids who took home assignments had higher test scores and retention rates. To the delight of teachers everywhere, Rupp confirmed that “homework plays an important role in student learning.”

3. HIGH HEELS HURT.

A woman walking up stairs, in pain, holding her black high heels.
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High heels exaggerate your posture, tilt your hips, and shorten your stride. Some evolutionary psychologists argue they’re part of our primal urge to compete for mates. While that’s up for debate, science has confirmed that high heels are pretty much terrible for you. A study by the Institute for Aging Research found that 64 percent of older women who regularly wore unsupportive shoes—like high heels, pumps, or sandals—at some point in their life complained of foot pain.

4. PIGS LOVE MUD.

A pink piglet with black spots raising its mud-covered snout.
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Pigs don’t have much in the way of sweat glands, which makes controlling body temperature a problem. So, for the longest time, scientists believed pigs wallowed in mud to keep cool. Although that’s true, a study in Applied Animal Behavior Science discovered an evolutionary twist: Porkers don’t roll in mud because they have just a few sweat glands; rather, they have a few sweat glands because they like to roll in mud. (Put differently, swine never developed sweat glands because their ancestors were always playing in muck!) Now some scientists believe a mud bath simply makes pigs happy. It’s a tautology, but pigs like mud because, well, they like mud.

5. CEREAL TASTES BETTER WITH MILK.

Milk being poured into a bowl of cereal.
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Scientists at the Pontifical Catholic University of Chile did the unthinkable—they added water to corn flakes. They found that the “intermolecular interactions in the flake’s matrix could be weakened by the plasticizer, leading to the solubilization of some components, and ... a decrease in mechanical integrity.” Translated into English? Water makes cereal soggy. Milk, it turns out, is special. The fat content protects cereal from sucking in too much liquid, keeping it crispy.

6. MEN STARE AT WOMEN'S BOOBS.

A man staring at women in a bar.
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In an article titled "My Eyes are Up Here," Sarah Gervais and her team used eye-tracking technology to confirm what we’ve long suspected—men like ogling at women’s chests. Men spent more time looking at a woman’s body than her face. Their eyes wandered the most if the woman had—surprise!—wide hips, a narrow waist, and large breasts. But women were just as guilty: They stared to scope out the competition.

7. OVEREATING CAN LEAD TO WEIGHT GAIN ...

A man, shown from the neck down, sitting on a couch holding a beer with a burger and fries on a plate in his lap.
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Between the 1970s and now, the average adult in the U.S. gained 19 pounds. Research presented at the European Congress of Obesity in 2009 found that “weight gain in the American population seems to be virtually all explained by eating more calories,” study leader Boyd Swinburn said. Laziness had little to do with America’s tightening belt.

8. ... AND EATING BAD FOOD IS BAD FOR YOU.

A plate of fried chicken, macaroni and cheese, and mashed potatoes.
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If you were holding out hope that fried chicken was a staple of a well-balanced diet, science has some bad news for you. A 2013 study in the American Journal of Medicine tracked the effect of eating habits on participants' health from middle-age on. The research involved assessing the diet of 5350 adults (age 51.3 ± 5.3 years, 29.4 percent women) and then tracked their mortality, chronic diseases and overall health after 16 years. The results: "[P]articipants with a 'Western-type' diet (characterized by high intakes of fried and sweet food, processed food and red meat, refined grains, and high-fat dairy products) had lower odds of ideal aging."

9. MEETINGS SUCK.

A man with his head on his arms, face down, during a meeting.
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A 2005 study in Group Dynamics found that meetings are annoying time-sapping killjoys. By analyzing the diary entries of 37 university workers, researchers concluded that meetings make employees stressed and grumpy, hindering even the most motivated workers from getting things done.

10. READING IS GOOD FOR YOUR BRAIN.

Two girls reading a book in the library.
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Your second grade teacher was right. Experts put Ph.D. candidates inside an MRI and had them read Jane Austen’s Mansfield Park. At one point, they were told to read for pleasure. Then they were told to read analytically (as if they were studying for a test). In both cases, their brains' blood flow increased. Under each condition, blood flowed to different parts of the noggin. Each style of reading prompted different—and beneficial—brain patterns. “Literary study provides a truly valuable exercise of people’s brains,” said project leader Natalie Phillips. Rejoice, English majors! (Here are a few other reasons you should be reading more.)

11. PARTY SCHOOLS LOVE TO PARTY.

A lot of red cups set up for a game of beer pong.
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It took a decade of research, but a team at Harvard School of Public Health finally did it—they confirmed Playboy’s sneaking suspicion. Students binge drank more if their school had a reputation for drinking and partying. The survey of 50,000 students at 120 colleges showed that, although the student body changes year by year, the ratio of heavy to casual drinkers stays the same.

12. THE INTERNET IS WHERE PRODUCTIVITY COMES TO DIE.

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The Internet is an amazing tool with the power to do the world infinite good. But, wait. Look! It’s a bear riding a bicycle! According to Pew Research, 53 percent of people between the ages of 18 and 29 go online once a day just to waste time.

13. MEN AND WOMEN DESIRE A SEXUALLY ATTRACTIVE PARTNER.

A young couple all bundled up for a winter beach date.
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A team of researchers subjected willing undergrads to a word-association assignment to test how much they associate physical attractiveness with an ideal partner. Regardless of how the same participants responded when asked directly about the importance of appearance in a mate, they were quick to report positive feelings when shown words related to sexiness. "If a person tells me, for example, that she doesn't care about how attractive a guy is, our research suggests that her claim isn't worth all that much," study researcher Paul Eastwick, of Texas A&M University, said in a statement.

14. PEOPLE WILL BUY MORE FRUITS AND VEGETABLES IF THEY'RE CHEAPER.

A man and woman looking at apples in the supermarket.
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Just because we've told you that all that fried food is bad for you doesn't mean you're going to change your ways—but there is one thing that is proven to encourage the purchase of more produce: discounts. A 2013 paper published in the American Journal of Clinical Nutrition reported on a trial done in Dutch supermarkets in which participants were given 50 percent off produce coupons, nutrition education, both, or neither. The researchers found that people bought and consumed more fruits and vegetables if they were given the coupons. They consumed even more if they got the discount and the education, but if they got just the education there was no effect. Of course, this is important information for crafting public health initiatives, but did they really need the study to know people prefer to spend less money?

15. MUSICIANS GET THE GIRLS.

A man, shown from the nose down, playing a guitar.
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Tales of rock stars and groupies provide more than enough anecdotal evidence to know this is true, but does the musician vibe really make a man more attractive if he's not in a world-famous band? Spoiler alert: yes. A French research team enlisted a young man (who was “previously evaluated as having a high level of physical attractiveness”) to stand on a street and request phone numbers from 300 different young ladies—all in the name of science, of course. For 100 such solicitations he was holding a guitar case; for another 100 he had a sports bag; and for the final 100, he was empty handed. According to the researchers, "Results showed that holding a guitar case was associated with greater compliance to the request, thus suggesting that musical practice is associated with sexual selection." No word on whether or not he followed up with any of the 31 percent of women who offered the apparent guitarist their digits.

16. STEREOTYPICALLY "SEXY" WAITRESSES GET BETTER TIPS.

A close shot of a waitress's arm as she carries a tray of food.
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One caveat: This whole study, published in the Archives of Sexual Behavior, is based on self-reporting some rather personal details. But there's little cause to question findings that support such an obvious trend (not to mention Hooters' whole business model). Waitresses completed an online survey that included subjective assessments of their own attractiveness and sexiness as well as objective attributes like bust size, hair color, and tip amounts. You can probably predict what happened: "The waitresses’ tips varied with age in a negative, quadratic relationship, increased with breast size, increased with having blond hair, and decreased with body size."

17. "PRE-GAMING" BEFORE YOU HIT THE BAR MEANS MORE ALCOHOL OVERALL.

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Imagine that: Drinks at home plus drinks at the bar equals more overall drinks. A study from Switzerland shows that the intent to defray the cost of alcohol out at the bar with a "pre-gaming" event doesn't really work. Instead, people still imbibe just as much while they're out on the town, which just gets added to their drinks from at home. According to LiveScience, "The study also found that those who pre-drank were more likely to suffer risky or unfavorable consequences of drinking, such as blackouts, hangovers, unplanned substance abuse or unprotected sex." That's probably a result of the more overall drinks.

18. PEOPLE CHANGE CLOTHES BASED ON THE WEATHER.

A woman, pictured from the back, looking into her closet.
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In 2007, researchers from Italy and Denmark published an article looking into people’s clothing choices depending on the weather and indoor environment. While it might seem obvious, the researchers were curious because many employees will drive to work inside a heated/cooled vehicle and then work for the day in a heated/cooled building. Ultimately, the researchers wrote “The outdoor temperature at 6 a.m. seems to affect people's choice of clothes the most.”

19. PEOPLE ARE HAPPIER WHEN THEIR SPOUSES ARE GENEROUS ... OR IF THEY'RE HAVING LOTS OF SEX.

A man puts his hand over his partner's eyes as he hands her a gift.
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The results of a survey of more than 1400 heterosexual couples between the ages of 18 and 46—all of whom had children—published in 2011 as part of the National Marriage Project showed that higher levels of reported generosity correspond to a happier marriage. That's right: People like getting backrubs, flowers and unsolicited acts of niceness, so much so it actually makes them happy. Of course, not as happy as regular sex might. While generosity is good, it was sexual satisfaction that proved to be the most consistent indicator of a happy marriage.

20. EXPERTS HAVE GOOD INTUITION

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If you have an expensive handbag you’re worried might be counterfeit, would you rather trust the gut feeling of an expert or the carefully reasoned logic of an amateur? That’s the question a group of researchers from three universities answered in a 2012 study. They took a bunch of students and told them to identify real Coach/Louis Vuitton handbags from counterfeits. Some were told to base their judgement entirely on intuition, while others were told to be analytical. Among both groups were “experts,” or people with “more than three Coach and/or Louis Vuitton handbags.” According to a press release, “the researchers found that intuition was more effective for those with high expertise. In the intuition condition, participants with high expertise demonstrated higher task performance. In the analysis condition, those with high expertise performed no better than those with low expertise.”

Written by Lucas Reilly, Hannah Keyser, and Austin Thompson. Versions of this story ran in 2014 and 2015.

Blue Apron’s Memorial Day Sale Will Save You $60 On Your First Three Boxes

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Scott Eisen/Getty Images

If you’ve gone through all the recipes you had bookmarked on your phone and are now on a first-name basis with the folks at the local pizzeria, it might be time to introduce a new wrinkle into your weekly dinner menu. But instead of buying loads of groceries and cookbooks to make your own meal, you can just subscribe to a service like Blue Apron, which will deliver all the ingredients and instructions you need for a unique dinner.

And if you start your subscription before May 26, you can save $20 on each of your first three weekly boxes from the company. That means that whatever plan you choose—two or four meals a week, vegetarian or the Signature plan—you’ll save $60 in total.

With the company’s Signature plan, you’ll get your choice of meat, fish, and Beyond foods, along with options for diabetes-friendly and Weight Watchers-approved dishes. The vegetarian plan loses the meat, but still allows you to choose from a variety of dishes like General Tso's tofu and black bean flautas.

To get your $60 off, head to the Blue Apron website and click “Redeem Offer” at the top of the page to sign up.

At Mental Floss, we only write about the products we love and want to share with our readers, so all products are chosen independently by our editors. Mental Floss has affiliate relationships with certain retailers and may receive a percentage of any sale made from the links on this page. Prices and availability are accurate as of the time of publication.

26 Fascinating Facts About the Human Body

Ridofranz/iStock via Getty Images Plus
Ridofranz/iStock via Getty Images Plus

You may not think about it very often, but there's so much to learn about the human body. For instance, did you know that people are actually covered in invisible stripes? In this article, which was adapted from an episode of The List Show, we take a look at some fascinating facts about the human body you might not know.

1. Only humans have chins.

Humans are the only animals with chins. While you may think every animal has one, that’s just what we tend to call the bottom of the head. But in reality, a chin is a very specific bone feature that extends forward from the lower jaw. Some experts propose that elephants and manatees have chins, but others argue that they’re such fundamentally distinct structures they shouldn’t be compared to humans. Experts still aren’t sure why people evolved to have chins; the reason might have to do with eating or speaking, or they may just have emerged as a side effect from some other useful feature.

2. Humans have a strange bone called the hyoid.

A peculiar bone humans have is the hyoid. This is the one bone that doesn’t form a joint with another bone. Instead, it’s connected to muscles and ligaments. The hyoid sits between the jaw and the voice box and it’s used to keep all the lower mouth muscles in place. It also helps with swallowing and talking.

3. People that have more hair and innie belly buttons are more prone to lint.

Hairy people with innie belly buttons are more prone to belly button lint, which comes from fibers that rub off of clothing over time. Your stomach hair grabs onto the fibers and pulls them into your belly button.

Starting in 2011, a group of scientists started the Belly Button Biodiversity Project to learn about what's going on inside these little caves of mystery, and as it turns out, it's quite a lot. Samples from about 60 people revealed over 2300 total species of bacteria. And of those, only eight were identified as common, appearing in over 70 percent of belly buttons.

4. While it varies person to person, fingernails grow faster than toenails.

Your fingernails grow faster than your toenails. Though it varies from person to person, typically, fingernails grow about a tenth of a millimeter each day, while toenails grow at around half that pace. There’s a correlation between nail growth speed and the length of the nearest bone. This means that your longest fingers have faster-growing nails than your shorter fingers.

5. Fingernails grow faster on your dominant hand.

Your fingernails grow faster on the hand that you write with. No one knows why.

6. As you age, your nails change.

Specifically, they grow more slowly and then nail cells, known as onychocytes, start accumulating. That’s why older people have thicker toenails. Fingernails aren’t as noticeably different because people manage them better, plus our toes endure a lot of damage throughout our lives.

7. It's a misconception that people's hair and nails continue to grow after they die.

What’s actually happening is the skin dehydrates and then recedes. So it looks like the hair and nails are getting longer, but in reality it's actually the skin that's getting shorter.

8. Breastfeeding will not cause breasts to sag.

It's a common misconception that breastfeeding causes breasts to sag. Pregnancy itself might affect breasts in that they may stretch and then recover differently. But research on breastfeeding confirms it will not cause breasts to sink. A behavior that will, though, is smoking.

9. Hands and feet contain over half the bones in an adult body.

With around 27 bones in each of your daddles—that’s an old slang word for the hands—and about 26 bones in each of your plates of meat—which is another old slang term for feet—these appendages account for over half of an adult’s bones, of which there are around 206 total. But that’s not always true. Feet mostly contain cartilage at birth, then bones form over time. They don’t fully harden until humans are in their early twenties.

10. You can fracture a rib just by sneezing.

While it's rare, it is possible to fracture a rib by sneezing. In 1885, there was an article in the Journal of the American Medical Association about a 72-year-old man who fractured his eighth rib while sneezing. Sneezer, by the way, is a 1940s Australian slang term meaning “excellent, wonderful,” which could definitely describe a good sneeze—but probably not one that would break a rib.

11. You can see stars if you rub your eyes.

If you've ever seen stars while rubbing your eyes, you’re not imagining it. The cells in our eyes are interpreting the pressure as an input, and treat that the same way they’d treat a light input.

12. Goosebumps are pretty much useless.

Goosebumps are frequently associated with adrenaline being released in the body, like when we’re feeling a particularly strong emotion, for example. They used to be important when people had way more hair on their bodies because goosebumps would elevate that hair and make a person look bigger when they were in danger. But now, they’re a pretty useless feature.

13. Spleens help the immune system.

The spleen is surprisingly not totally useless even though that was the belief up until the 1950s. It’s OK to get your spleen removed, but it does assist the immune system. While blood is in the spleen, the immune system creates the necessary antibodies to fight bacteria in that blood. A fetus’s spleen also creates red blood cells.

14. The appendix seems to help the immune system.

It's OK to get your appendix removed, but the organ also aids the immune system. In 2018, Dr. Mohamad Abouzeid, assistant professor and attending surgeon at NYU Langone Health told Mental Floss, "[The appendix] has a high concentration of the immune cells within its walls." Experts don't know exactly how the appendix affects the immune system, but it seems to play some role in keeping us healthy.

15. A fetus's face forms in the first three months after conception.

During the first three months after conception, a fetus’s face comes together, fusing in the area of the top of the lip. That means the dent under the nose, which is called the philtrum, is evidence of a person's time in the womb.

16. Babies don’t just see in black and white.

A newborn baby has pretty terrible vision. But it’s not true that they can only see in black and white. In reality, if there’s a large amount of the color red, they can identify it, but only if it appears in front of gray. Newborns have about 5 percent of the visual acuity that adults do, but it improves quickly and takes only around six months before they can see about as well as a grown-up. Though there are some eye tests that babies can school adults on, which are ones centered around subtlety. For example, up until 6 months old, a baby can tell monkeys apart, while older babies and adults can’t do that.

17. The liver is very good at regenerating itself.

In fact, with just 25 percent of the original liver tissue, it can regenerate. Liver transplants are generally only needed if someone has experienced severe damage to the organ or an injury.

18. Some people are born with three kidneys.

Some people had a kidney split while they were still in the womb, so they're actually born with three. This makes them prime candidates for donation, but the problem is people often don't know when they have three kidneys.

19. A person's large intestine can be stretched 5 feet and the small intestine can stretch 20 feet.

The intestines are pretty long: The small intestine stretches to about 20 feet and the large intestine hits 5 feet. The surface area of your intestines could take up two entire tennis courts, although some Swedish researchers have downgraded it to studio apartment size. Compare that with a blue whale, though, which has over 700 feet worth of intestines.

20. The stomach can hold up to 50 fluid ounces.

The stomach may not be tennis court size, but it can hold around 16 to 50 fluid ounces. It's interesting to note that a Trenta size at Starbucks is 31 fluid ounces, which is more than many adult stomachs can technically hold.

21. The neurotransmitter serotonin can be found in the gut.

Our gut contains 95 percent of the neurotransmitter serotonin. In fact, the gut, with its 100 million neurons, is so important to mood that it’s sometimes called the “second brain.” Medications that affect serotonin will often also cause GI issues.

22. The skin is the largest organ.

The skin is considered an organ and it's the body's largest one. An adult may have 22-square feet of skin on their body. Basically that means your skin could comfortably stretch across half the floor of the typical bathroom.

23. The skin makes up a large part of your body weight.

Fifteen percent of your total body weight, to be exact.

24. The ovaries are in communication with the brain.

It was once believed that the ovaries and uterus sort of sat dormant until they were needed, but the ovaries actually communicate with the brain in ways we’re just learning about. The hypothalamus and ovaries work together to make sure that the levels of hormones in the ovaries, like estrogen and progesterone, are where they need to be.

25. Humans are covered in stripes.

The human body is covered in stripes called Blaschko’s Lines, which are typically invisible. They’re cellular relics of our development from a single cell to a fully formed human.

26. Humans glow, but our eyes aren't able to detect it.

Humans glow, but it’s just around 1000 times weaker than our eyes can detect. Every animal that has metabolic reactions glows because in that process, photons get emitted, causing light. In 2009, a study was published in which a camera captured the bioluminescence of five men. According to that study, our upper body lights up the strongest. And the glow is on a cycle; when we’re on a normal sleep schedule, our bioluminescence is at its strongest at about 4 p.m.