Life has been growing on Earth for about 4 billion years, and during that time there have been a handful of mass extinctions that have wiped out a large percentage of complex lifeforms. Asteroid impact, volcanic eruption, climate change, anoxia, and poison have dispatched untold numbers of once-successful species to total oblivion or a few lucky fossils. Species also die off regularly for much less spectacular reasons, and altogether about 98% of documented species no longer exist.
Cry me a river, you say, without all that death there would have been no gap for vertebrates, for mammals, for primates, for humanity. The tyrannosaurus-less world we awoke to find ourselves on had regained an incredible array of plant, animal, fungal, and microbial diversity, exploiting and even seeming to celebrate every ecological niche on the planet. Our ancestors, a small population of soft, slow-moving meatbags, lifted their hands from the ground and set about smashing, shaping, shooting, burning, cutting and eating their way to the top. Although human tribes spread to inhabit every continent except Antarctica, the limits of the world remained unknown, no less to tribal cultures than to pre-Columbian Europe. There was always the promise of more land, more meat, and more resources for the taking—perhaps not within easy reach, but somewhere near the horizon.
Even after Europe discovered the “new” world, attitudes of conquest and dominion were rarely given second thought. Manifest destiny drove United States citizens from sea to shining sea, eradicating all kinds of biodiversity along the way. We not only disregarded the finity of plants and animals, but of a remarkably diverse race of peoples who lived in equilibrium with a world they recognized as precious. But after the West was won, the global balance of power shifted very quickly. Industry, technology, and medicine led to unprecedented health and fecundity. Global population exploded exponentially. There was nowhere left to go.
Now it is humanity that strives toward limitlessness while the world seems to dwindle, inexorably, under our feet. Like a dark cloud of volcanic ash circling the globe, we stifle and kill species on a massive scale in not much less sudden a fashion. Even when we keep our hands clean, we contribute to global warming, pollution, and deforestation just by maintaining a modern lifestyle. We are a mass extinction event, and we are still unfolding.
But as we know, mass extinctions are not the end of the world, and on the contrary, they offer new beginnings for life on Earth. Whether humanity remains a part of that life remains to be seen. Complex, intelligent life has evolved from rudimentary beginnings before and can do so again. And as one of the largest biomasses on the planet, humanity could speciate in the wake of ecological collapse and fragmentation. How we evolve could surpass our wildest dreams.
But I like being human, and I consider our world a beautiful place, one worth savoring and not throwing away. Unlike any natural disaster we have the gift of agency and choice, of intelligence, foresight, and decision. We are coming to terms with a small world that is getting smaller, and we will surely react and adapt to this knowledge as best we can. But no outcome is inevitable. All action and inaction will have an impact. If we want to remain who we believe ourselves to be, we must choose to respect life, to value and foster diversity, to just take it easy once in a while, to control our primal appetites, and to change our very nature. Only by choosing to change, rather than having to change, can we truly stay human.