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Is Your Sense of Direction Innate?

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Some people are like homing pigeons: Drop them off anywhere, and they’ll find their way around. Other people, though, can’t tell when they’re holding a map upside down. Are the directionally challenged just bad learners? Or are some of us just lucky to be born with a strong internal compass?

Not all of your navigational skills are learned. There’s evidence that your sense of direction is innate. (Some of it, at least.) Your brain is packaged with special navigational neurons—head-direction cells, place cells, and grid cells—and they help program your internal GPS when you’re just a wee tot.  

In 2010, two different studies (here and here) explored whether rats were born with a sense of direction. Scientists implanted electrodes in the brains of baby rodents and tracked their neural activity. Although the rats were newborns, the researchers discovered that their head-direction cells (which help us recognize the direction we’re facing) were fully mature. The rats, it seemed, were born with an intrinsic sense of direction. And they hadn’t even opened their eyes yet!

Humans, of course, are not rats. But the hippocampus—the brain region responsible for navigation and spatial memory—is similar in most mammals. If the rat’s internal compass develops this way, then it’s likely that a human’s compass does, too.

Off the Grid

If we’re born with a sense of direction, then why are some people so good at getting lost? The scientists found that the two other cells—place and grid cells—developed within the first month. Place cells are thought to help us form a mental map, while grid cells help us navigate new and unfamiliar places. The two cells interact—and that’s where the trouble might be.

In a 2013 study from Nature, participants played a video game that required them to shuttle back and forth between virtual locations. Monitoring their brains, the scientists found that grid cells helped the gamers keep track of their whereabouts—even without landmarks. According to researcher Michael Kahana and the Daily Mail, it’s a “reasonable assumption that differences in how grid cells work explain why some people have a better sense of direction than others.”

So rejoice, navigationally challenged people! If you’ve ever gotten lost pulling out of your driveway, your may now blame your grid cells.

Of course, the nature-nurture argument isn’t black and white here. Although this neural network is hardwired from the time you’re born, it matures thanks to your interactions with the world. These connections are like the prefab wiring in your house, while your experiences with the environment are like the solder that makes that wiring stronger. Both help.  

Will a GPS mess with this wiring?

A GPS may save your behind now and then, but it may meddle with your navigational skills if you depend on it to get everywhere. We naturally get around by using a process called “dead reckoning.” Basically, you estimate where you are by comparing your location to a reference point. You use a mental map to make these estimates. Problem is, when you rely on a GPS, that mental map can get foggy.

A 2005 study at the University of Nottingham asked people to drive to a specific spot. Some of them were given step-by-step directions, while others were handed an old-fashioned map. At the end of their journey, they were asked to sketch out the route they traveled. The folks who were given instructions drew the most inaccurate maps. People who used a GPS to walk around a city faced the same problem.

Two things are to blame. First, when you depend on a GPS, you’re more likely to ignore your surroundings. You don’t memorize as many landmarks because you don’t need to. As a result, your mental map is less detailed. That’s why people who depend on a GPS sometimes panic during detours. By updating the map on their GPS, they fail to update the map in their brain.

The second reason isn’t as earth shattering. A GPS usually prevents you from huge blunders (disclaimer: OK, sometimes not). People who navigate on their own are more likely to screw up. Thankfully, the experience of committing a gaffe actually improves their mental map. Making mistakes remains one of the best ways to learn. 

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Big Questions
Where Did the Myth That Radiation Glows Green Come From?
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by C Stuart Hardwick

Probably from radium, which was widely used in self-luminous paint starting in 1908. When mixed with phosphorescent copper-doped zinc sulfide, radium emits a characteristic green glow:


Quora

The use of radioluminescent paint was mostly phased out by the mid-1960s. Today, in applications where it is warranted (like spacecraft instrument dials and certain types of sensors, for example), the radiation source is tritium (radioactive hydrogen) or an isotope of promethium, either of which has a vastly shorter half life than radium.

In most consumer products, though, radioluminescence has been replaced by photoluminescence, phosphors that emit light of one frequency after absorbing photons of a difference frequency. Glow-in-the-dark items that recharge to full brightness after brief exposure to sunlight or a fluorescent light only to dim again over a couple of hours are photoluminescent, and contain no radiation.

An aside on aging radium: By now, most radium paint manufactured early in the 20th century has lost most of its glow, but it’s still radioactive. The isotope of radium used has a half life of 1200 years, but the chemical phosphor that makes it glow has broken down from the constant radiation—so if you have luminescent antiques that barely glow, you might want to have them tested with a Geiger counter and take appropriate precautions. The radiation emitted is completely harmless as long as you don’t ingest or inhale the radium—in which case it becomes a serious cancer risk. So as the tell-tale glow continues to fade, how will you prevent your ancient watch dial or whatever from deteriorating and contaminating your great, great grandchildren’s home, or ending up in a landfill and in the local water supply?

Even without the phosphor, pure radium emits enough alpha particles to excite nitrogen in the air, causing it to glow. The color isn’t green, through, but a pale blue similar to that of an electric arc.


Quora

This glow (though not the color) entered the public consciousness through this early illustration of its appearance in Marie Curie’s lab, and became confused with the green glow of radium paints.

The myth is likely kept alive by the phenomenon of Cherenkov glow, which arises when a charged particle (such as an electron or proton) from submerged sources exceeds the local speed of light through the surrounding water.

So in reality, some radionuclides do glow (notably radium and actinium), but not as brightly or in the color people think. Plutonium doesn’t, no matter what Homer Simpson thinks, unless it’s Pu-238—which has such a short half life, it heats itself red hot.


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

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Big Questions
How Are Royal Babies Named?
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Jack Taylor, Getty Images

After much anticipation, England's royal family has finally received a tiny new addition. The birth of the Duke and Duchess of Cambridge's second son was confirmed by Kensington Palace on April 23, but the name of the royal newborn has yet to be announced. For the heir to the British throne and his wife, choosing a name for their third child—who is already fifth in line to the throne—likely won't be as easy as flipping through a baby name book; it's tradition for royals to select names that honor important figures from British history.

According to ABC WJLA, selecting three or four names is typical when naming a royal baby. Will and Kate followed this unwritten rule when naming their first child, George Alexander Louis, and their second, Charlotte Elizabeth Diana. Each name is an opportunity to pay homage to a different British royal who came before them. Some royal monikers have less savory connotations (Prince Harry's given name, Henry, is reminiscent of a certain wife-beheading monarch), but typically royal babies are named for people who held a significant and honorable spot in the family tree.

Because there's a limited pool of honorable monarchs from which to choose, placing bets on the royal baby name as the due date approaches has become a popular British pastime. One name that keeps cropping up this time around is James; the original King James ruled in the early 17th century, and it has been 330 years since a monarch named James wore the crown.

If the royal family does go with James for the first name of their youngest son, that still leaves at least a couple of slots to be filled. So far, the couple has stuck with three names each for their children, but there doesn't seem to be a limit; Edward VIII, who abdicated the throne to George VI in 1936, shouldered the full name of Edward Albert Christian George Andrew Patrick David.

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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