Why Is Yawning Contagious?

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iStock

What is yawning? And why do we do so much of it? Neuroscientist and yawn expert Robert Provine says it's "ancient and autonomic." It stems from early evolution and is common to many creatures—even fish do it. It's autonomic in the sense that it roots in the brainstem, way down in the basement level of the brain, where certain responses are so built-in they don't even qualify as reflexes.

Yawning has many triggers, including boredom, sleepiness, and temperature. A 2014 study suggested that there's a "thermal window" (at around 68°F) for human yawning; as ambient temperature approaches body temperature or goes down near freezing, we yawn less. According to the paper, we may yawn to regulate the temperature of our brains. This isn't the same as saying we yawn to take in extra oxygen, as evidence to date says we don't. It means that yawning might act to draw brain-soothing ambient air in through the nose and mouth.

COPYCAT YAWNING?

Over the years, scientists have observed "contagious yawning" in chimpanzees, humans, baboons, bonobos, wolves, and, to a certain extent, dogs. Yawning feels good, so why not join in when someone else yawns? Well, you're not really "joining in," because you aren't copying the yawn on any conscious level. It happens because you just can't help it. If you become self-conscious about a yawn, it stops.

While many past studies have documented the phenomenon, a more recent study, published in the journal Adaptive Human Behavior and Physiology, contends that yawns may not be contagious after all—or at least that we have not yet proven it. Experimental psychologist Rohan Kapitány of the University of Oxford conducted a review of the scientific literature on contagious yawns and found very little conclusive evidence to back up our long-held assumption that yawns are contagious.

"The belief that yawns are contagious seems self-evident," Kapitány told PsyPost, "but there are some very basic reasons for why we might be mistaken in this. If we fail to dissect that which we think we know, we might end up with conclusions that do not reflect reality. In this instance, the literature hasn't questioned the basic features of contagious yawning, and ended up with a wide range of unstandardized methodologies and conclusions."

Still, because Kapitány's study was small and extremely limited, he and his fellow authors urge other scientists to challenge their findings with experiments of their own.

"I may be wrong!" Kapitány said. "Maybe yawns are contagious!" Kapitány says he'd like to see "more robust" attempts to falsify the claim that yawns are contagious rather than "simply demonstrating it over and over [in] slightly different contexts with richer and richer explanations."

WHO DOESN'T CATCH YAWNS?

Some people with autism or schizophrenia don't exhibit a yawn-contagion response. The same is true of children under the age of four years. This has led to a variety of theories about yawning's relationship to empathy and the brain's mirror-neuron system (MNS). The idea here is that MNS deficits might lead to missing hidden empathetic cues that trigger contagious yawning. The MNS seems to be involved in the process to some extent. fMRI scans on a range of people have shown that other parts of the brain also "light up" in response to images of yawning, perhaps more so than the areas normally associated with empathy.

YAWN AND RUN

Parts of the amygdala—a brain area associated with fear and heightened attention—light up in response to images of yawning. We sometimes yawn when we're nervous, such as before a sporting performance.

So, perhaps we yawn at those times to prepare our brains for "fight or flight." Maybe contagious yawning is a smart evolutionary shortcut for readying the brains of an entire group of hominins for swift action in response to a threat. (If that's the case, then some older members would have been left behind, because older people are a little less susceptible to yawn contagion.) We are social mammals; this kind of evolutionary refinement of an existing trait (general purpose yawning becoming contagious yawning) might have helped groups to survive.

Or maybe it's a lot less deep than that. Laughing also feels good, and it too can be contagious. Like laughter, contagious yawning might help groups to bond—by signaling unselfconscious, relaxed sleepiness. Perhaps it has more to do with feeling safe than with feeling threatened.

STRAGGLERS AND FAKES

Contagious yawning is still a bit of a scientific mystery. We love to speculate about it and try to home in on the reason for it. But why should an evolutionary trait have one specific reason behind it? Often, traits survive because they cover a number of bases. Other times, they're simply evolutionary stragglers whose original purpose has faded out, but because they don't work against a creature's survival, there's no pressure to get rid of them.

One modern adaptation of yawning is not so contagious—fake yawning. You might do this as a less-than-subtle means of signaling that a conversation has dragged on too long. Why not engage in a scientific experiment next time you're in a meeting with your boss? Lean back in your chair and yawn, then note down whether he or she yawns right back at you. Maybe there's a scientific discovery in there … but probably no pay raise.

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What Is the Kitchen Like on the International Space Station?

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iStock/Elen11

Clayton C. Anderson:

The International Space Station (ISS) does not really have a "kitchen" as many of us here on Earth might relate to. But, there is an area called the "galley" which serves the purpose of allowing for food preparation and consumption. I believe the term "galley" comes from the military, and it was used specifically in the space shuttle program. I guess it carried over to the ISS.

The Russian segment had the ONLY galley when I flew in 2007. There was a table for three, and the galley consisted of a water system—allowing us to hydrate our food packages (as needed) with warm (tepid) or hot (extremely) water—and a food warmer. The food warmer designed by the Russians was strictly used for their cans of food (about the size of a can of cat food in America). The U.S. developed a second food warmer (shaped like a briefcase) that we could use to heat the more "flexibly packaged" foodstuffs (packets) sent from America.

Later in the ISS lifetime, a second galley area was provided in the U.S. segment. It is positioned in Node 1 (Unity) and a table is also available there for the astronauts' dining pleasures. Apparently, it was added because of the increasing crew size experienced these days (6), to have more options. During my brief visit to ISS in 2010 (12 days or so) as a Discovery crewmember, I found the mealtimes to be much more segregated than when I spent five months on board. The Russians ate in the Russian segment. The shuttle astronauts ate in the shuttle. The U.S. ISS astronauts ate in Node 1, but often at totally different times. While we did have a combined dinner in Node 1 during STS-131 (with the Expedition 23 crew), this is one of the perceived negatives of the "multiple-galley" scenario. My long duration stint on ISS was highlighted by the fact that Fyodor Yurchikhin, Oleg Kotov, and I had every single meal together. The fellowship we—or at least I—experienced during those meals is something I will never, ever forget. We laughed, we argued, we celebrated, we mourned …, all around our zero-gravity "dinner table." Awesome stuff!

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

Clayton "Astro Clay" Anderson is an astronaut, motivational speaker, author, and STEAM education advocate.

His award-winning book The Ordinary Spaceman, Astronaut Edition Fisher Space Pen, and new children's books A is for Astronaut; Blasting Through the Alphabet and It's a Question of Space: An Ordinary Astronaut's Answers to Sometimes Extraordinary Questions are available at www.AstroClay.com. For speaking events www.AstronautClayAnderson.com. Follow @Astro_Clay #WeBelieveInAstronauts

What Do the Numbers and Letters on a Boarding Pass Mean?

iStock.com/Laurence Dutton
iStock.com/Laurence Dutton

Picture this: You're about to embark on a vacation or business trip, and you have to fly to reach your destination. You get to the airport, make it through the security checkpoint, and breathe a sigh of relief. What do you do next? After putting your shoes back on, you'll probably look at your boarding pass to double-check your gate number and boarding time. You might scan the information screen for your flight number to see if your plane will arrive on schedule, and at some point before boarding, you'll also probably check your zone and seat numbers.

Aside from these key nuggets of information, the other letters and numbers on your boarding pass might seem like gobbledygook. If you find this layout confusing, you're not the only one. Designer and creative director Tyler Thompson once commented that it was almost as if "someone put on a blindfold, drank a fifth of whiskey, spun around 100 times, got kicked in the face by a mule … and then just started puking numbers and letters onto the boarding pass at random."

Of course, these seemingly secret codes aren't exactly secret, and they aren't random either. So let's break it down, starting with the six-character code you'll see somewhere on your boarding pass. This is your Passenger Name Reference (or PNR for short). On some boarding passes—like the one shown below—it may be referred to as a record locator or reservation code.

A boarding pass
Piergiuliano Chesi, Wikimedia Commons // Public domain

These alphanumeric codes are randomly generated, but they're also unique to your personal travel itinerary. They give airlines access to key information about your contact information and reservation—even your meal preferences. This is why it's ill-advised to post a photo of your boarding pass to social media while waiting at your airport gate. A hacker could theoretically use that PNR to access your account, and from there they could claim your frequent flier miles, change your flight details, or cancel your trip altogether.

You might also see a random standalone letter on your boarding pass. This references your booking class. "A" and "F," for instance, are typically used for first-class seats. The letter "Y" generally stands for economy class, while "Q" is an economy ticket purchased at a discounted rate. If you see a "B" you might be in luck—it means you could be eligible for a seat upgrade.

There might be other letters, too. "S/O," which is short for stopover, means you have a layover that lasts longer than four hours in the U.S. or more than 24 hours in another country. Likewise, "STPC" means "stopover paid by carrier," so you'll likely be put up in a hotel free of charge. Score!

One code you probably don’t want to see is "SSSS," which means your chances of getting stopped by TSA agents for a "Secondary Security Screening Selection" are high. For whatever reason, you've been identified as a higher security risk. This could be because you've booked last-minute or international one-way flights, or perhaps you've traveled to a "high-risk country." It could also be completely random.

Still confused? For a visual of what that all these codes look like on a boarding pass, check out this helpful infographic published by Lifehacker.

Have you got a Big Question you'd like us to answer? If so, send it to bigquestions@mentalfloss.com.

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