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.

A man smiling while he types on his laptop.
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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.

A group of people clinking full shot glasses together.
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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

A woman holds out two hands and smiles.
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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.

Could Gigantic Coconut Crabs Have Played a Part in Amelia Earhart’s Mysterious Disappearance? At Least One Scientist Thinks So

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Getty Images

Amelia Earhart's disappearance during her attempt to fly around the world has captivated historians and conspiracy theorists for more than 80 years. One organization is now suggesting that her fate may have been sealed by giant crabs.

The International Group for Historic Aircraft Recovery (TIGHAR) believes that Amelia Earhart and navigator Fred Noonan may have landed their plane on Nikumaroro Island when they couldn't find their target, Howland Island, and that Nikumaroro's endemic crustaceans may have played a part in the ensuing mystery.

According to National Geographic, there are several clues supporting TIGHAR's theory. The large reef that hugs Nikumaroro’s coast makes it conducive to emergency aircraft landings. In 1940—just three years after Earhart’s disappearance—British colonists found 13 human bones beneath a ren tree on the island and shipped them to Fiji, where they were lost. The colony's administrator, Gerald Gallagher, sent a telegram back to England positing that it was Earhart’s skeleton. Then, in 2001, researchers uncovered U.S.-made artifacts around the ren tree including a jackknife, a woman’s compact, a zipper, and glass jars. The plot thickened even further in 2017, when four forensic bone-sniffing dogs all indicated that a human had indeed died at the site, though excavators failed to dig up any more evidence.

If those 13 bones beneath the ren tree did belong to the unfortunate castaway, where are the rest of her remains? Tom King, TIGHAR’s former chief archaeologist, thinks that coconut crabs can answer that question.

Nikumaroro is home to thousands of the colossal creatures, which can grow to a terrifying 3 feet across and weigh 9 pounds. They’re sometimes called robber crabs because of their penchant for absconding with objects that smell like food, and they’ll eat practically anything—coconuts, fruit, birds, rodents, other crabs, their own discarded body parts, and carrion.

It’s not unreasonable, then, to think that coconut crabs may have feasted on Earhart’s corpse and then taken her bones home with them. In one experiment to test the theory, TIGHAR researchers deposited a pig carcass on the island and filmed the aftermath. With the help of small strawberry hermit crabs, coconut crabs stripped the pig down to the bone in two weeks. After a year, some of the bones had been dragged 60 feet from the carcass’s original location, and some were never recovered at all.

King believes Earhart’s missing 193 bones could be hidden in the burrows of various coconut crabs. As in the pig experiment, crabs may have scattered some of Earhart’s bones dozens of feet away, but maybe not all of them—after all, the forensic dogs smelled bones near the ren tree that haven’t yet been located. Right now, TIGHAR is working with the Canine Forensics Foundation to further explore the area.

While we wait for more answers, dive into these other theories about Earhart’s disappearance.

[h/t National Geographic]

10 Juicy Facts About Leeches

Ian Cook
Ian Cook

Leeches get a bad rap, but they’re actually pretty cool once you get to know them—and we're finding out more about them, even today. Recently, a team led by Anna Phillips, curator of parasitic worms at the Smithsonian National Museum of Natural History, discovered a new species of medicinal leech (pictured above) in a Maryland swamp. We asked parasite expert and curator at the American Museum of Natural History Mark E. Siddall to share some surprising facts about the worms we love to hate. 

1. Not all leeches suck blood.

Hematophagous, or blood-feeding, species are only one type of leech. “The vast majority of species are [hematophagous],” Siddall tells Mental Floss, “but it depends on the environment. In North America, there are probably more freshwater leeches that don’t feed on blood than there are blood-feeders.” And even among the hematophagous species, there are not too many who are after you. “Very few of them are interested in feeding on human blood,” Siddall says. “Certainly they’ll do it, if they’re given the opportunity, but they’re not what they’re spending most of their time feeding on.” 

2. Leeches are everywhere.

Japanese leech on a log
Pieria, Wikimedia Commons // Public Domain

“Every continent on the planet has leeches, with the exception of Antarctica,” Siddall says. “And even then there are marine leeches in Antarctic waters.” Humans have co-existed with leeches for so long, according to Siddall, that just about every language has a word for leech. 

3. Leeches have made a comeback in medicine.

Bloodletting for bloodletting’s sake has fallen out of favor with Western physicians, but that doesn’t mean medicinal leeches are enjoying a cushy retirement. Today, surgeons keep them on hand in the operating room and use them as mini-vacuums to clean up blood. “That is a perfectly sensible use of leeches,” Siddall says. Other uses, though, are less sensible: “The more naturopathic application of leeches in order to get rid of bad blood or to cure, I don’t know, whatever happens to ail you, is complete hooey,” he says. How on Earth would leeches take away bad blood and leave good blood? It’s silly.” 

4. Novelist Amy Tan has her own species of leeches.

Land-based leeches made an appearance in Tan’s 2005 book Saving Fish from Drowning, a fact that instantly put the author in leech researchers’ good graces. “There are not a lot of novels out there with terrestrial leeches in them,” Siddall says. So when he and his colleagues identified a new species of tiny terrestrial leeches, they gave the leech Tan’s name. The author loved it. “I am thrilled to be immortalized as Chtonobdella tanae,” Tan said in a press statement. “I am now planning my trip to Queensland, Australia, where I hope to take leisurely walks through the jungle, accompanied by a dozen or so of my namesake feeding on my ankles.”

5. Leeches can get pretty big.

The giant Amazon leech (Haementeria ghilianii) can grow up to 18 inches and live up to 20 years. And yes, this one’s a blood-feeder. Like all hematophagous species, H. ghilianii sticks its proboscis (which can be up to 6 inches long) into a host, drinks its fill, and falls off. Scientists thought the species was extinct until a zoologist found two specimens in the 1970s, one of whom he named Grandma Moses. We are not making this up.

6. Leeches make good bait.

Many walleye anglers swear by leeches. “A leech on any presentation moves more than other types of live bait," pro fisher Jerry Hein told Fishing League Worldwide. "I grew up fishing them, and I think they're the most effective live bait around no matter where you go." There’s an entire leech industry to provide fishers with their bait. One year, weather conditions kept the leeches from showing up in their typical habitats, which prevented their collection and sale. Speaking to CBS news, one tackle shop owner called the absence of leeches “the worst nightmare in the bait industry.”

7. Leech scientists use themselves as bait.

Siddall and his colleagues collect and study wild leeches. That means hours of trekking through leech territory, looking for specimens. “Whether we’re wandering in water or traipsing through a bamboo forest,” Siddall says, “we are relying on the fact that leeches are attracted to us.” Do the leeches feed on them? “Oh my god, yes. We try to get them before they feed on us … but sometimes, obviously, you can’t help it.”

8. Leech sex is mesmerizing.

Like many worms, leeches are all hermaphroditic. The specifics of mating vary by species, but most twine themselves together and trade sperm packets. (The two leeches in the video above are both named Norbert.)

9. Some leech species make surprisingly caring parents. 

“There’s a whole family of leeches that, when they lay their eggs, will cover them with their own bodies,” Siddall says. “They’ll lay the eggs, cover them with their bodies, and fan the eggs to prevent fungus or bacteria from getting on them, and then when the eggs hatch, they will attach to the parent. They’re not feeding on the parent, just hanging on, and then when the parent leech goes to its next blood meal it’s carrying its offspring to its next blood meal. That’s pretty profound parental care, especially for invertebrates.”

10. You might be the next to discover a new leech species. 

Despite living side-by-side with leeches for thousands of years, we’ve still got a lot to learn about them. Scientists are aware of about 700 different species, but they know there are many more out there. “I’ll tell you what I wish for,” Siddall says. “If you ever get fed on by a leech, rather than tearing off and burning it and throwing it in the trash, maybe observe it and see if you can see any color patterns. Understand that there’s a real possibility that it could be a new species. So watch them, let them finish. They’re not gonna take much blood. And who knows? It could be scientifically useful.”

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