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Why Are Some People More Prone To Mosquito Bites?

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And by "some people" I mean me. Why is it that an evening stroll leaves me feeling eaten alive while my companions are left blissfully un-bitten?

First of all, it's probably not all in my head (although it could be — most people are bad sources about their own mosquito attractiveness). Studies suggest that about 20 percent of people are "high attractor types" who are especially appealing to the female mosquitoes seeking out blood for the extra protein they need to lay eggs. Of course, not all mosquitoes are the same. There are 150 different species in the United States, each with their own blood-sucking proclivities. But since you probably won't know — or care — if the bugger biting you is Culex pipiens or Aedes aegypti, let's consider some of the more general properties that affect your mosquito appeal.

Clothing Color

It's true, mosquitoes have discerning fashion taste. Or at least, they're more likely to spot you as a target if you stand out from your environment. Dark colors, especially, will attract more of the insect.

Movement

Similarly, the more you move, the easier you are to identify as a living, breathing, vessel full of delicious blood.

Body Heat

Visual clues allow the mosquito to locate you from relatively far away, but as she approaches, it's your body heat that draws her in. This puts pregnant women, who average about 1.26 degrees Fahrenheit warmer than others, at a particular risk — a fact which has been substantiated by a number of studies.

Carbon Dioxide

This is another reason pregnant women are at a disadvantage. Mosquitoes can detect carbon dioxide using a special organ called a maxillary palp from as far as 164 feet away. Since everyone emits CO2 simply by exhaling, it comes down to relative amounts. Unfortunately for mothers-to-be, pregnancy causes women to emit 21 percent more CO2. This is also why kids are often safe from bites, when bigger, more CO2-emitting adults are around.

Alcohol Intake

On the flip side, pregnant women are (presumably) avoiding another mosquito attractor: alcohol. Although it's unclear how mosquitoes go about detecting the presence of ethanol, studies show that drinking even just 12 ounces of beer will significantly increase the attention you receive from the pests.

The Properties of Your Skin and Sweat

Up to 85 percent of your susceptibility to mosquito bites has nothing to do with what you're drinking or wearing — it's just genetic. Specifically, the composition of your skin bacteria — the kind that naturally and healthily exists there — can serve as an attractor. As can the levels of lactic acid, uric acid, ammonia, and other substances present in your sweat.

Blood Type

Another factor you can't control? Your blood type. And it stands to reason that, if the mosquito is there to suck your blood, she cares what kind she's getting. People with blood type O are more prone to mosquito bites than those with type B, with type A folks bringing up the rear.

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What Happens When You Flush an Airplane Toilet?
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For millions of people, summer means an opportunity to hop on a plane and experience new and exciting sights, cultures, and food. It also means getting packed into a giant commercial aircraft and then wondering if you can make it to your next layover without submitting to the anxiety of using the onboard bathroom.

Roughly the size of an apartment pantry, these narrow facilities barely accommodate your outstretched knees; turbulence can make expelling waste a harrowing nightmare. Once you’ve successfully managed to complete the task and flush, what happens next?

Unlike our home toilets, planes can’t rely on water tanks to create passive suction to draw waste from the bowl. In addition to the expense of hauling hundreds of gallons of water, it’s impractical to leave standing water in an environment that shakes its contents like a snow globe. Originally, planes used an electronic pump system that moved waste along with a deodorizing liquid called Anotec. That method worked, but carrying the Anotec was undesirable for the same reasons as storing water: It raised fuel costs and added weight to the aircraft that could have been allocated for passengers. (Not surprisingly, airlines prefer to transport paying customers over blobs of poop.)

Beginning in the 1980s, planes used a pneumatic vacuum to suck liquids and solids down and away from the fixture. Once you hit the flush button, a valve at the bottom of the toilet opens, allowing the vacuum to siphon the contents out. (A nonstick coating similar to Teflon reduces the odds of any residue.) It travels to a storage tank near the back of the plane at high speeds, ready for ground crews to drain it once the airplane lands. The tank is then flushed out using a disinfectant.

If you’re also curious about timing your bathroom visit to avoid people waiting in line while you void, flight attendants say the best time to go is right after the captain turns off the seat belt sign and before drink service begins.

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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Why is Friday the 13th Considered Unlucky?
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Today, people around the globe will feel uneasy about getting out of bed, leaving their homes, or going about their normal daily routines, all because of a superstition. These unfortunate folks suffer from paraskavedekatriaphobia, a common neurosis familiar to us all: the fear of Friday the 13th. But just where did this superstitious association come from, and how did it catch on?

The truth is that no one is absolutely sure where the idea that Friday the 13th is unlucky originated. Donald Dossey, the founder of the Stress Management Center and Phobia Institute in Asheville, North Carolina, suspects the fear can be traced back to a Norse myth about 12 gods who had a dinner at Valhalla—the fabled hall where legendary Norse heroes feasted for eternity after they died—that was interrupted by a 13th guest, the evil and mischievous god Loki.

According to legend, Loki tricked Höðr (the blind god of winter and son of Odin, the supreme god in Norse mythology) into shooting his brother Baldr (the benevolent god of summer who was also a son of Odin) with a magical spear tipped with mistletoe—the only substance that could defeat him. Thus the number 13 was branded as unlucky because of the ominous period of mourning following the loss of such powerful gods by this unwanted 13th guest.

For whatever reason, among many cultures, the number 12 emerged throughout history as a "complete" number: There are 12 months in a year, 12 signs of the zodiac, 12 Gods of Olympus, 12 sons of Odin, 12 labors of Hercules, 12 Jyotirlingas or Hindu shrines where Shiva is worshipped, 12 successors of Muhammad in Shia Islam, and 12 tribes of Israel. In Christianity, Jesus was betrayed by one of his 12 Apostles—Judas—who was the 13th guest to arrive for the Last Supper. Surpassing the number 12 ostensibly unbalances the ideal nature of things; because it is seen as irregular and disrespectful of a sense of perfection, the number 13 bears the stigma of misfortune and bad luck we know today.

WHY FRIDAY?

Friday joins in the mix mostly because all of the early accounts of Jesus’s crucifixion agree that it took place on Friday—the standard day for crucifixions in Rome. As Chaucer noted in The Canterbury Tales, "And on a Friday fell all this mischance." Yet perpetuating Friday as an unlucky day in America came from the late 19th-century American tradition of holding all executions on Fridays; Friday the 13th became the unluckiest of days simply because it combined two distinct superstitions into one. According to the Oxford University Press Dictionary of Superstitions, the first reference to Friday the 13th itself wasn’t until 1913. (So despite actually occurring on Friday, October 13, 1307, the popular notion that the Friday the 13th stigma comes from the date on which the famed order of the Knights Templar were wiped out by King Philip of France is just a coincidence.)

The repercussions of these phobias reverberated through American culture, particularly in the 20th century. Most skyscrapers and hotels lack a 13th floor, which specifically comes from the tendency in the early 1900s for buildings in New York City to omit the unlucky number (though the Empire State Building has a 13th floor). Some street addresses also skip from 12 to 14, while airports may skip the 13th gate. Allegedly, the popular Friday the 13th films were so-named just to cash in on this menacing date recognition, not because the filmmakers actually believed the date to be unlucky.

So, is Friday the 13th actually unlucky? Despite centuries of superstitious behavior, it largely seems like psychological mumbo jumbo. One 1993 study seemed to reveal that, statistically speaking, Friday the 13th is unlucky, but the study's authors told LiveScience that though the data was accurate, "the paper was just a bit of fun and not to be taken seriously." Other studies have shown no correlation between things like increased accidents or injuries and Friday the 13th.

And Friday the 13th isn't a big deal in other cultures, which have their own unlucky days: Greeks and Spanish-speaking countries consider Tuesday the 13th to be the unluckiest day, while Italians steer clear of Friday the 17th. So today, try to rest a little easy—Friday the 13th may not be so unlucky after all.

Additional Source: 13: The Story of the World’s Most Popular Superstition.

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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