There's growing evidence that Earth may be headed for a mass extinction, where over 75 percent of all species die out and the world is changed forever. There's also evidence that humans would survive such an event — for better or for worse. Here's why.
Over the past half-billion years, life on Earth suffered through five mass extinctions, where the majority of species on the planet died off and a whole new set of ecosystems rose up to replace them. Most of us have heard about the most recent catastrophe like this, when an asteroid hit the planet and, along with some ferociously large volcanoes in India, managed to wipe out almost the entire dinosaur population 65 million years ago. Instead of a world of dinosaurs, we now live in a world dominated by furry mammals like ourselves. Below, you can see a timeline of Earth's previous mass extinctions.
So why do I have the audacity to claim that humans could survive events like these? I've been thinking about this question a lot over the past few years, as I researched and wrote my book Scatter, Adapt and Remember: How Humans Will Survive a Mass Extinction. Quite simply, there's a solid body of evidence that suggests Homo sapiens has the characteristics of a mass extinction survivor species. As geologist and mass extinction expert Mike Benton put it, the animals who make it through planetary disasters tend to be adaptable and live at high population sizes — just like humans. Whatever our flaws, you can't accuse us of having a small population. Nor can you say that we don't know how to adapt to pretty much any crazy environment on Earth — as well as environments in space, beneath the ground, and under the water.
Indeed, our incredible adaptability puts us in league with some of the planet's greatest survivor species, like cyanobacteria (blue-green algae) and sharks. Both species survived more than one mass extinction, and they did it by basically being willing to live anywhere and eat whatever crap they could. Which — again, just like humans.
But here's what humans have that sharks and algae don't. We are able to learn from the past, including the deep geological past of our planet, and we're able to plan for the future. For example, geologists and paleontologists know that most of the previous mass extinctions on the planet were caused by climate change. Volcanoes or asteroids ripped the planet apart, loading the atmosphere with carbon and other poisons. The oceans went acidic and the climate got so hot that lots of species died out. At other times, sudden ice ages gripped the planet, locking once-temperate regions like Antarctica into massive blocks of ice.
Unlike sharks, humans are in a position to understand the dangers that await us if the climate changes too much. And, even better, we can do something about it.
Already, scientists and governments are putting money and time into developing forms of energy that don't load the environment with carbon. On a smaller scale, municipalities are trying to become more efficient. The government of Copenhagen recently pledged to make the entire city carbon neutral by 2025. Entrepreneurs are creating inexpensive new technologies that help small farms produce fertilizer and grow food in a carbon negative way.
But, you might be saying, humans are also polluting the environment in unprecedented ways. We're driving many life forms extinct. Plus, we're getting more efficient at killing each other every year, either directly in war or indirectly during famines. Do we really deserve to survive?
It's easy to slip into judgmental mode when we're talking about the future of humanity, moving quickly from the question of whether we can survive to whether we actually deserve it. I'm often shocked by how many of us feel that humanity shouldn't go on. People who are horrified by the death penalty will cheerfully opine that the entire species should be consigned to extinction because we are such bloodthirsty, carbon-barfing creeps.
But if you think that humans are the first species to destroy the planet's atmosphere, you are suffering from a species-level delusion of grandeur. Billions of years ago, cyanobacteria poisoned the Earth by farting out so much oxygen that our methane-dominated environment became oxygen-dominated. Only the creatures who could breathe oxygen made it through (along with a few extremophiles). It was pollution by oxygen — the opposite of today's pollution by carbon. Meanwhile, there is strong evidence that ants, chimps, and even dolphins go to war with each other. My point is that humans aren't the biggest bastards on Earth. We're in good company.
Like every other animal who ever lived, humans have a will to survive that transcends ethics, culture and beliefs. We're not going to survive because we deserve it. We're going to do it because we're adaptable and there are a lot of us. Take out 6 billion humans and you still have a billion left.
So for me, the question is what our survival will look like. Homo sapiens could survive a radiation disaster by moving underground, eating bugs and mold, slowly losing the ability to speak and write over millennia of tragic evolution. Or we could survive by planning for the future, based on what we know about the Earth's history. We can begin the slow process of mitigating climate change, retrofitting our cities to be carbon neutral and changing our agricultural practices so that we enhance species diversity. We can plan ways to mitigate other disasters too, like asteroid strikes and earthquakes and famines.
Whether you believe we deserve to or not, Homo sapiens will be around for many more millennia. So we'd better start planning now how to make that survival as good and healthy as possible. Of course there are always going to be disasters we can't plan for, no matter how nice we are: A supernova could fry off a chunk of our atmosphere, or a pandemic could drop our population down to a few million. But if we don't prepare ourselves for these and other eventualities, our survival could be a pretty ugly thing that nobody deserves.
Will we be scrabbling out an existence in the ruins, or building robust cities and exploring the spaces beyond our planet's puny envelope of atmosphere? That's up to us, right now.
I've got some ideas about how we might do it. Check out my book if you want to find out more!
Annalee Newitz is the author of Scatter, Adapt and Remember: How Humans Will Survive a Mass Extinction. She'll be on book tour in May — here are the dates and places where she'll be, so come out and say hi.