THE FUTURE IS LOOKING GRIM. We’re beginning to feel the effects of climate change, as superstorms and megadroughts strike with increasing regularity. Extinctions are ripping through amphibian populations in the Americas, while bees are threatened by colony collapse disorder. Indeed, many environmental scientists believe that we’re in the early stages of a mass extinction, where over 75 percent of all species on Earth may eventually be wiped out. When you look at humans—with our fleshy, vulnerable bodies, need for a 21 percent oxygen atmosphere, and susceptibility to disease—the odds don’t exactly seem to be in our favor.
But the apocalypse is complicated. The planet has already suffered through five mass extinctions in the past half-billion years, and geological history reveals that these catastrophes often take a million years. There is no sudden tipping point or global zombie scourge: Doom usually comes slowly. And through the shocks that Earth has experienced before, some organisms have always found a way to survive.
So here’s some encouraging news: Humans happen to have a lot in common with many of the species that have made it through previous mass extinctions—plus a few advantages of our own. And that means there just might be hope for human survival after all. Here are some of the reasons we might make it—along with a few survivor role models from millennia past.
We have a large population
Life forms with high populations are much more likely to survive the world-transforming events that precipitate mass extinctions. It’s likely that trilobites survived two mass extinctions because they were so populous and diversified into so many species; their characteristic fossils can be found all over the world. (They eventually died out after ruling the oceans for 250 million years.) Like trilobites, humans have seen our population explode, to a number that recently exceeded 7 billion individuals. Take out billions, and there are still billions left.
We can live in many environments
Mass extinctions are often set off by a major disaster, like an enormous volcano or asteroid strike. But what kills all those species are the climate changes set off by these catastrophes, which unleash carbon and other toxins that rapidly cool or warm the planet. Two hundred and fifty million years ago, an enormous volcano in what is now Siberia erupted for over 1,000 years, unleashing millions of tons of carbon into the atmosphere and setting off horrific global warming. A humble creature named Lystrosaurus survived by migrating across the world’s megacontinent and adapting to new geological niches. The Lystrosaurus is in the synapsid family, and related species in that family evolved into mammals. Like Lystrosaurs, humans can live anywhere, at a range of temperatures and in many different ecosystems.
We can eat anything
The ancestors of sharks survived at least three mass extinctions. Sharks are a “generalist” species, which means they feed on a variety of foods in many different habitats. They can even eat garbage and survive. Humans can do that, too. So if we find ourselves in a situation where food supplies dwindle, we will still be able to eke out an existence eating bugs, slimes, and other perfectly fine sources of nutrition that most of us to do not ordinarily consider a meal.
We can mimic evolution
Among the greatest mass extinction survivors in history are cyanobacteria, or blue-green algae. They evolved over 3 billion years ago, and managed to persist through so many planetary disasters because they evolved a nearly foolproof survival mechanism: photosynthesis. When your main energy source is light, you can make it through pretty much any apocalypse that doesn’t involve the death of the sun. Recently, with photovoltaic cells, humans have hit upon a way to draw power from the sun, too. By imitating the evolutionary strategy of cyanobacteria, we have a chance to save ourselves.
We understand the causes of disasters and how to defend against them
Finally, we have an advantage over every survivor organism so far. As far as we know, none of these other survivor species was able to understand what caused the mass extinctions they endured—nor were they able to plan survival strategies for future catastrophes. But humans can do that. We understand that most mass extinctions were caused by climate change, and that the planet’s climate is changing now. Plus, we’re beginning to develop the technology to arrest it. The future may not be easy, but one thing is likely: Humans have what it takes to stick around.
Annalee Newitz is the author of “Scatter, Adapt and Remember:
How Humans Will Survive A Mass Extinction,” and the editor-in-chief of io9.com
Correction: Because of a reporting error, an earlier version of this article incorrectly described the evolutionary role of the lystrosaurus. Other related species in the synapsid family were what evolved into mammals.