It's impossible to turn on the news or go the movies without hearing about some disease or cataclysm that's about to end the world. There's a movie coming (2012) that as far as we can tell is about every apocalypse happening at once, and in the news the flavor of the week is swine flu--though so far the fatality rate has fallen rather short of, say, Popsicles.
Our apocalypse fixation ignores the fact that the things we're afraid of are old-hat. Extinction level events have happened again and again throughout history and, lo and behold, we're still here. And hell, we probably wouldn't be without number five...
5The K-T Extinction
Everyone knows this story: For millions of years, dinosaurs roamed the earth, snacking on the odd mammal that was unfortunate enough to get in their way. They were big, hungry and had some terrifying weaponry.
As for mammals, our only saving grace was that we bred like crazy and were too small to easily kill. We presumably spent our days scurrying in terror and it was pretty clear who'd won the genetic lottery.
Then one sunny day 65 million years ago, a big rock fell out of the sky like a game of cosmic billiards gone drunkenly sour. This falling space matter is suspected to have made the 110-mile-wide Chicxulub crater in the Yucatan.
To understand the scale of the collision, know that according to newer versions of the theory, the crater in question was caused by only one of several fragments of a larger asteroid that did to our planet what a falling cinder block does to a Chihuahua. Also remember that the Yucatan crater is 100-damn-miles across.
The initial blast(s) threw up enough ash to blot out the sun, killing all plant life. With the plants gone, the food chain snapped, leaving all the dinos yabba-dabba dead. The mammals' policy of being small and annoying paid off, and they grew up to be us, you and the Knicks City Dancers.
"Suck it, T-Rex!"
The K-T rock was six-miles across. If that sounds big, know that the earth is approximately 7,000-miles across (which is quite small by stellar standards). Heck, K-T wasn't even the biggest one to hit our planet--a few billion years ago, one such impact shat out the entire moon.
Don't worry, though. The good news is that we have dedicated teams of nerds giving up their social lives to stare at the night sky in order to tag and track most cosmic debris in the solar system longer than a mile.
The bad news is that objects smaller than mile across can still ruin your day, particularly if your name is Ann Hodges.
4The Clovis Comet
So could something like K-T happen to humans? Well, it already did. In Michigan. Crap.
They call it the Clovis Comet, and if you want a very small idea of the scale of this thing, look at the above photo.
At first glance, you may believe that this image is the result of nuclear testing, rabid beavers or some horrifying combination thereof. In fact, this is a picture of the aftermath of the Tunguska explosion, which demolished Siberia in 1908. The blast, which some scientists attribute to an earthbound comet, leveled 80 million trees with the force of 1,000 Hiroshimas.
Scary, right? Now raise Tunguska to the power of "holy fuck" and you'll get an inkling of how devastating the Clovis Comet was. "How devastating?" you query. Well experts say it was an explosion equal to about 1.5 billion Hiroshima bombs (or 20 million Megatons).
The Clovis Comet exploded over the Great Lakes about 12,900 years ago. The blast ignited continent-wide forest fires, spurred global cooling and killed all the neat animals like mastodons and 14-foot tall grizzly bears.
We're actually glad he's extinct.
As humanity's big innovation that millennia was putting the meat on sticks before cooking it, we weren't in much of a position to do anything about the biosphere turning into tears and excrement, so we apparently gritted our teeth and boned our way back to the top.