Popular Science Winter 2018

NO, THAT’S NOT A MINI maelstrom tearing up your stomach. It’s one of the most incredible chemical symphonies on our planet: the human physiological response to danger. Your endocrine system dumps adrenaline, dopamine, and other hormones into your blood, which ratchets up your senses (enhance!), and tells your heart to start feeding your muscles extra juice. Your respiration increases to take in more oxygen. Coiled for imminent action, your body is primed to fight—or get the heck outta there. You are now superhuman. At least, temporarily. We share this transformation with animals across the natural world, twirling between routine and high alert. As you examine the causes and effects of this fear dance, you can’t help but notice that one creature’s danger is just another’s afternoon snack. Or, for some aspects…

Mara Hvistendahl At the outset of her career, Mara Hvistendahl wasn’t planning to report on science and technology. But when the Mandarin-speaking Minnesota native moved to China in 2004 after college, she found topics such as healthcare and the environment to be of central importance there—and drastically under-covered by her stateside colleagues. So Hvistendahl started filling in that gap, writing about everything from cyber-espionage for the MIT Technology Review to sex-selective abortion in her book Unnatural Selection: Choosing Boys over Girls, and the Consequences of a World Full of Men, a finalist for the 2012 Pulitzer Prize in nonfiction. For her latest feature, on page 50, Hvistendahl traveled to England, where she met with researchers advocating for responsible development of artificial intelligence, which they believe will surpass human brainpower. Her next…

HUMANS HAVE BEEN JUMPING, SLIDING, and explosively ejecting from imperiled airborne vehicles since World War I. But clearing crewmembers from doomed planes soaring as high as 80,000 feet—without killing them—has taken more than a century of refinement. Now, the most advanced ejection seats boast survival ratings above 90 percent. This is how we got there. 1975 Electric feel McDonnell Douglas’ ACES II became the Air Force standard, replacing a hodgepodge of seats by different makers. It featured quick-firing, rocket-powered chutes, and was more reliable—the first to time ejection sequences electronically instead of using mechanical or pyrotechnic delays. LATE 1960S A better handle Once aviators donned helmets, there was no need to lower protective face screens before skedaddling. Martin-Baker found it speedier to trigger escape mechanisms with a handle between pilots’ legs. Hardware is in the same spot…

DEATH CAN COME IN MANY forms, avocados included. If we can stomach enough of them, many of our daily foods are lethal. Down 30-plus glasses of water in a few hours, for instance, and you’ll do yourself in. (One major cause of MDMA-related deaths: water intoxication caused in part by drug-induced extreme thirst.) Of course, the human stomach usually doesn’t hold much more than 4 cups, but the toxic effects of overindulgence can build up as your intestines move the food along. Here’s how much you’d need to eat of a few foods to flirt with fatality. BEEF LIVER Organ meats pack more nutrients than muscles. Livers in particular contain so much vitamin A that overindulgence overloads our own livers—and increases intracranial pressure to hazardous levels. WATERMELON Heaps of any fluid-rich fruit could kill…

IN 2011, AN OUTBREAK—NOT OF DISEASE, BUT OF TORNADOES—SLAMMED THROUGH a large swath of the Southern and Eastern U.S. The region saw 64 individual twisters on April 25, and another 50 the next day, but the worst still lay ahead. A head-spinning 199 tornadoes touched down on April 27, killing 316 and injuring almost 3,000. To compare this cluster to others, meteorologists use the Destruction Potential Index. DPI is the sum of each individual storm’s destructive capacity, which weather-folk quantify by multiplying each tempest’s wind power by the area it hits. April 27’s outbreak reached 21,980. That’s three times the next-most devastating event in 2010. Disasters like these are getting worse. From 1954 to 1963, the average outbreak—a sequence of six or more F1 or greater tornadoes that begin within six…

Of the millions of kids pinging soccer balls around at weekend tournaments, only a small fraction will make it to a Division 1 college team. Just a sliver of that group will reach the pros. Increasingly, those long odds push athletes (often at the behest of parents) to select a single sport in order to grind out a competitive edge. But mounting evidence shows that clearing a child’s schedule of all other recreation might sabotage their shot at the big leagues. Players are picking their games earlier and earlier. The average high-school athlete in 2016 had focused on a single sport since age 12, two years younger than those in college that same year. To compete, the logic goes, tykes need to focus on one thing as soon as possible, and…