#2. The Great Oxygenation Event Gave Us Air
Since we breathe oxygen, it's hard to think of the oxygenation of the planet as a disaster. But it was -- the Great Oxygenation Event almost killed off all life before it even got started.
Sometime around 2.4 billion years ago, the planet's atmosphere was as noxious as a truck stop Port-A-Potty. And anaerobic organisms like the ancestors of blue-green algae loved that poisonous, shitty air. They thrived on it. They ate it up and farted out oxygen as their waste product.
And they laughed every single time.
And for a while, this was a strictly bacterial world, because who else can live on poison and oxygen farts? Even the oxygen farts got gobbled up by iron deposits, creating rust-filled oxygen sinks that were no good to anyone. Then something crazy happened -- one of these stupid bacteria figured out "Oh shit, the sun!" and started using the process of photosynthesis to stay alive. Some scientists think that bacteria got so good at their job that their oxygen waste products ran out of room and started accumulating in the atmosphere. If you thought the dinosaur extinction was bad, you're right. We loved those guys. But the sudden influx of what was then a toxic element was bad, too, because it killed off just about every single living thing on the planet. It wouldn't be the first time we almost farted ourselves out of existence.
While most organisms at the time couldn't survive swimming in a sea of their own filth, others figured things out by detoxifying the space around them or clustering together to stay alive. Boom -- complex organisms, baby! It took a few million years, but still. We couldn't have done it with all that methane in the air.
And so the world's first paparazzi was born.
But that would hardly be the last time that a horrific, disastrous calamity would force life to get its act together ...
#1. The Snowball Earth Got Complex Life Forms Rolling
As bad as global warming would be, it's nothing compared to what we would face if we were hit with a new ice age. About 650 million years ago, the planet entered the worst ice age in its entire history due to what scientists call the "fuck if we know" theory. (Although some suspect it might have had something to do with the previously mentioned oxygenation event that converted the atmosphere's methane into carbon dioxide.) As the temperature dropped, massive glaciers started to cover the planet, creeping slowly from the poles like mildew covering a rotting fruit.
Evidence suggests that the entire planet was covered in a thick sheet of ice for several million years, and the average temperature of the globe during that time might have plunged as low as -50 degrees Celsius. This planetary deep freeze happened at least three times.
"Oh, this is some bullshit right here!"
If it sounds like nothing should have been able to survive that, you're right. But once again, life found a way.
The fossil record tells us that complex animals started popping up about 650 million years ago, around the same time a sheet of ice covered the planet. Some researchers think that all those moving glaciers would have knocked the continents around, dumping large amounts of nutrients into the oceans trapped under the ice. While isolated, the earliest organisms used the influx of nutrients to get stronger, pruning out their weakest lines and rebuilding their genetic makeup. In the face of imminent death, they might have banded together and specialized functions in order to increase their chances of survival, inventing new features and creating the first diversity in early multicellular organisms.
In other words, they got smarter, because they had to.
Not such a badass now, are you, T. rex? (No, seriously.)
Once the Earth thawed, life was free to build upon the survival abilities it learned during the ice age and get out of the ocean and colonize the land. This directly led to what is called the Cambrian Explosion, the greatest outburst of life (lifesplosion?), diversity, and complexity in the history of our planet.
But Earth had to turn into an inhospitable, frozen wasteland first. This would set the stage for what would become a running theme in our world: One species' disaster is another's savior.
Hahaha! Suck it, bitch!
Sebastien Paquin is a freelance writer and author of the longest and most ridiculous John Dies at the End fan fiction to ever lurk in the darkest corner of the Internet.
For more cataclysmic events that could destroy us, check out 5 Ways The World Could End (You'd Never See Coming) and 5 Cosmic Events That Could Kill You Before Lunch.