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 of our universe, threats are simply normal movement: Asteroids aren’t willfully attacking our planet any more than an elephant attacks the ground on which it steps. Still, each one creates real peril for whatever’s in its path.
Somehow, though, natural threats aren’t enough for us: We actively quest for dangerous situations—seeking out that choice adrenaline buzz. We board vehicles that reach ludicrous speeds; we create explosions just to see the smoke. If our animal cousins could comprehend why we do what we do, they’d probably think we were insane.
Or maybe they’d get it? Maybe that explains why a certain portion of the rodent population risks becoming roadkill by diving in front of my car—to gain cred in their squirrel community. Small-mammal motivations are almost certainly not that complex, but every resident of this planet does feel some snap of fear almost every day. We humans—the ones behind this magazine, anyway— sure are fascinated by it. So we decided to go long on danger: more than 100 pages designed to get