There are a lot of us. Humans, that is.
At latest count, nearly seven and a half billion, in fact. Humans, it could be said, are the most successful multi-cellular life form in Earth’s history. We’ve spread out across the globe, occupying nearly every corner of it. And while you might only find, say, a penguin in Antarctica, or a tiger in Asia, or an elephant in Africa, humans can be found everywhere. From the sun-drenched wastes of the Sahara to the frozen coasts of Svalbard, the dense rainforests of the Amazon to the rolling grasslands of Africa and North America, humans are everywhere. We are an endlessly adaptable species, capable of surviving in virtually any climate, thus covering a virtually limitless habitat range. We humans possess a unique skill for not only learning to adapt to any climate, but also to adapt virtually any climate to suit our needs. We have learned to built shelter, for warmth or shade. We’ve domesticated crops and livestock, allowing us to feed ourselves independent of our ecosystem.
The crux of it is that we humans are proven survivors. While there do exist certain major threats to our species (pandemics, the specter of nuclear war, the ever-present danger of global warming), at our current level of collective intelligence and technological sophistication, it is unlikely that any one of these threats, or even a combination of them, would be enough to completely eradicate humanity. Even if we fail to act on climate change, while the results would threaten most life on our planet, it’s likely that, at least for a time, our species would survive.
Yet, hard as it may be to comprehend from our limited vantage point, we are hardly safe. Every day we learn more about the workings of our universe, the history of our planet, our solar system, our galaxy. And, with each revelation, we discover new, far more serious threats to our survival.
Say a nearby star went supernova. Such an event, should it happen close enough to our planet, could potentially destroy our entire solar system, along with countless others across cosmic distances. Even if it happened far enough from us to spare Earth from the explosion, the event could still bombard our world with sufficient gamma radiation to exterminate all, or nearly all life on the planet.
Such threats need not come from beyond our solar system, either. Instabilities in our own sun could trigger solar flare events that could harm life on Earth. And don’t forget what happened to the dinosaurs. Asteroids remain a significant threat; our study of Earth’s history shows that we’ve had several extinction-level impacts. These events seem to occur every few million years or so, likely triggered by gravitational stresses knocking loose space debris from the outer solar system, sending massive bolides careening toward the inner planets. It’s been sixty-five million years since the last such event (and we all know what happened then). Based on observed trends, some scientists say we’re due for another.
Even then, there are ways we could potentially shield ourselves against such apocalyptic cosmic dangers. We likely already possess the means to defend Earth from catastrophic asteroid impacts (whether or not we could actually employ those means is a different question entirely). Perhaps, in time, we might even find a way to shield our planet from excess cosmic radiation, keeping us safe from solar flares or supernovae. Provided we survive long enough to develop such technology.
Ultimately, though, there may never be a way to protect our species from every threat to survival we face. While we ordinary people look around and see life proceeding as usual, everyone going about their daily routines as though it will all last forever, some cosmologists see a species balanced on a knife edge.
The simple fact of the matter is, every human in existence, every single one of us, lives on the surface of a single planet. We all go about our lives in what is, essentially, a single habitat. And all it would take is one unforeseen event, one bad day, to wipe our entire species out of existence. Here on Earth, biologists and conservationists have a term for a species found only in one isolated area, one incapable of surviving anywhere else, and thus vulnerable to being erased by one catastrophic incident.
An endangered species.
Our species has done a lot. Humans built the pyramids, the Great Wall of China, countless glittering skyscrapers at the heart of sprawling cities. We created the Mona Lisa, the statue of David. We built the Eiffel Tower. We produced such great minds as Leonardo da Vinci, Wolfgang Mozart, Albert Einstein, and Stephen Hawking. We’ve learned so much, discovered so much. It’s hard to imagine, after all we’ve done, all we’ve accomplished, that it could all be snuffed out in an instant. That the entire human story could end.
When preserving an endangered species, the base intent is always the same: to protect something unique and beautiful, something irreplaceable. We’ve often gone to great lengths to save species in peril; protected habitats, anti-poaching patrols, captive breeding programs. Once, we even considered a proposal in the United States to convert tracts of the Great Plains into a wildlife preserve for endangered African animals. Imagine: prides of lions, herds of elephants, flocks of ostriches, all roaming across the central United States…
Of course the proposal was shot down…but for our purposes, they may have been on to something. Ultimately, the best way to preserve any species is to diversify: to maintain populations in multiple locations, so that even if disaster befalls one group, the species itself will survive. With most species on Earth, this is no small task; after all, the Great Plains proposal stemmed from the similarities between the American Great Plains and the Serengeti in Africa. But, as we’ve established, we humans are survivors. We adapt. And there is one environment we’ve adapted to that remains inaccessible to any other species on our planet: space.
Many scientists, including such notable theorists as Carl Sagan and Stephen Hawking, have stressed that the colonization of space is imperative to the survival of our species. To survive, we must expand. Studies suggest that a permanent settlement of only one hundred humans could all but ensure our long-term survival. A single colony on another planet in our solar system would dramatically increase our chances of survival, ensuring that man would survive the destruction of Earth. The addition of interstellar colonies could potentially ensure human survival for millions of years.
Space exploration is often dismissed as too costly, too unnecessary, even frivolous. And it may often seem so, from our limited vantage point, standing as we are on the surface of our tiny world. As previously stated, from the narrow perspective of our personal lives it can feel as though all of this will be there forever. But as we face increasing existential threats both from our own misadventures and cosmic dangers beyond our planet, it may be time to accept the fact that we are, at least in the cosmic sense, an endangered species. Space exploration is not silly or childish, it is not frivolous; it is imperative. To guard our species against extinction, we must colonize space, we must expand.
If we do not, we may find ourselves going the way of the dodo, in the most literal sense of the phrase.