Sometimes I look around and I think, here we stand on the verge of becoming an interplanetary civilization - with no good reason why we can't go on to be interstellar, or even galactic - and most of us have no idea how lucky we are.
We got the Theia impactor to give us a huge moon with tidal effects, and Jupiter to keep our area swept reasonably clear of asteroids, at least since the Late Heavy Bombardment. We got abiogenesis within 700 million years of the crust of the planet cooling, when our g2 yellow dwarf still had five billion years left on the odometer before it definitely will cook the place.
But we weren't given that five billion years at the outset. The sun was getting warmer, and would have cooked the place in just two to two-and-a-half billion years if we hadn't reset the clock.
It was a last-minute save that reconfigured the planet. We breathed out oxygen which broke down the powerful greenhouse gas methane. If we hadn't, the warming sun would have cooked the place. But we did, so we got the Huronian Glaciation instead. Volcanos finally broke us out of that with CO2 greenhouse effects, meanwhile destroying the atmospheric oxygen. The albedo rose as the ice melted, and the planet would have cooked with the runaway feedback loop, except we started breathing again and took the CO2 out of the atmosphere.
So .... we'd have cooked except that we breathed out enough poison to destroy our warming effect plunging us into eternal winter. And we'd have frozen, except that volcanos restored a weaker kind of warming effect while removing the poison. And we'd have cooked again, except that we destroyed the weaker kind of warming effect while restoring the poison. And we'd have died of poisoning except that in the nick of time we got saved by the coincidental appearance of a completely unprecedented kind of freak that actually breathed the poison. And the new version of the planet had another few billion years before the warming sun will cook it, and the new oxygen-breathing life could get more energy from what was otherwise the same food.
That was all sheer luck. There is no reason why the timing of these things had to line up as perfectly as it did.
Now, as a side benefit, Oxygen in the upper atmosphere gave us ozone. That shielded the land from ultraviolet, and made it possible to survive outside the water. Which, admittedly, wasn't very important at the time, but it mattered later.
Next on the list of bizarre inexplicable strokes of luck, you have eukaryotes. Life up to that point had been prokaryotes. Prokaryotes are small and simple. Eukaryotes are incredibly complicated by comparison. They are huge cells thousands of times larger than a prokaryote, with hundreds of different organelles having specialized functions, nuclei containing DNA and specialized machinery for keeping the DNA checked and repaired, cell walls that form vacuoles, and a million other structures that prokaryotes had no precedent for. And most of them make no sense without most of the others already in place. But, bam, half a billion years after the Oxygen Crisis, there we are. With about 2.8 billion years left on the clock.
2.8 billion years is a pretty aggressive schedule for a eukaryote to build a launch vehicle, but here we are just 1.8 billion years later, so we're doing all right. We'd never have made it if we hadn't found a few more ways to hurry the schedule along though. And about 600 million years after that, we hit the evolutionary motherlode. This is the discovery whose anniversary we still celebrate every year with our annual Big Bang party: The invention of sex. We got there with about 2.2 billion years left before the clock runs out.
Sex allows macroorganisms to exist and evolve, which is to say plants and animals. It's really hard for one-celled organisms to develop a space program. And allowing for a way for macroorganisms to blend and exchange genetic information is essential for them to evolve. It allows mutations that took place in separate lineages to both or all appear in a common descendant. Sex sped up the evolutionary process by dozens of orders of magnitude, at least. Without it, we'd never have made this launch date.
Now, these aren't the only points where we got lucky. I could go on for days about stuff that's weird and quirky and bizarre that had to happen for us to survive this long and for us to get this advanced this fast. Earth is like a hothouse where conditions and blind luck have lined up so perfectly it's utterly crazy!
And yes, I'm aware of the Anthropic principle; we can't observe all the possible universes that didn't produce us, so we can't know how likely we were. But, gentle people, I direct your attention outward. To the great silence, where we have been diligently searching for any evidence of any civilization like us, or only a century or two more advanced than us, and we have not seen it. All those hundred billion stars in this galaxy that could have produced something like us, as far as we can tell, did not. All the quadrillion stars in the thousand galaxies close enough for our observations to be meaningful, as far as we can tell, did not. The Anthropic principle means we can't tell by our own existence anything about the likelihood of the events that created us, but The Great Silence means we can tell that there are a quadrillion stars where those events didn't happen and only one we know about where they did.
And the Anthropic principle cuts both ways. Time after time, life on Earth has survived. Disaster after disaster, hasn't happened. There is no ordered mechanism that keeps our climate stable in the long run; there is only a chaotic process, and chaotic processes sometimes crash. Ours hasn't crashed in the last three billion years, but we can't know whether that's because it was unlikely or because we were incredibly lucky. We only think there is an ordered mechanism because we have never seen it crash. And nothing prevents us from destroying ourselves. Obviously, we wouldn't be here to think about it if we had. We are not dwellers in a safe universe. We are Mister Magoo, the blind man who escapes death every twenty seconds and doesn't even realize he was ever in danger.
It is by sheer luck that we have not, so far, joined the Great Silence. And symbolic intelligences, like humans, are so far the rarest known survival strategy. We only have about a billion years left on the clock so humans are probably our last shot at this.
Don't blow it now.
