The Sixth Extinction

Review of Scatter, Adapt, and Remember by Annalee Newitz

Life on this earth has often been disturbed by terrible events. Countless living beings have been the victims of these catastrophes. Some inhabitants of dry land saw themselves swallowed up by floods. Others that lived in the bosom of the waters dried up when the bottom of the seas lifted suddenly. Their very races came to an end forever and leave in the world for the naturalist only a few barely recognizable remains.—Georges Cuvier (1)

Richard Leakey called it “the sixth extinction.” (2) At least five times before a substantial portion of life on Earth has gone extinct over a relatively short period of time. The Cretaceous-Paleogene extinction event that wiped out most of the dinosaurs—and more than 70% of all species—roughly 65 million years ago is only the most recent of these mass extinctions. The Permian-Triassic extinction 250 million years ago, in which some 90% of marine species died out, was even more severe. Based on the rate species are disappearing, scientists believe we may now be on the leading edge of a new mass extinction event of our own making. (3) We could even become one of its victims.

Annalee Newitz believes we can survive a sixth extinction. In her new book, Scatter, Adapt, and Remember: How Humans Will Survive a Mass Extinction, Newitz sees in this history of extinction not only the fragility of life, but also its resilience. After all, some creatures have survived each catastrophe. We ourselves may have rebounded from the brink of extinction once already in our short history. We are arguably the most adaptable species on the planet. We eat a wide variety of food and can live almost anywhere. Although we reproduce and evolve relatively slowly, our intelligence gives us the ability to adapt to changing circumstances in ways that other species cannot.

Newitz’ optimism may not be justified. Life on Earth must have survived for us to be around to consider our future chances. The survival of our ancestors is a necessary condition for being able to pose the question. It doesn’t tell us anything statistically about the survival of life elsewhere. This is what’s known as “observer selection bias”: every species that looks back will find that all its ancestors survived to reproduce.  But there may be any number of planets where life went extinct for every planet where life survived as long as it has here. We can’t generalize about the resilience of life in general from the skewed sample of our own history.

Nor does our own history necessarily give us reason for optimism. Our particular species of hominin has been around for no more 200,000 years. We can’t easily conclude from that relatively short period that we will survive another million years. Moreover, none of our nearly-human cousins manage to survive with us. That may be because we were more successful and they were unable to compete with us. But if we drove them to extinction, it’s possible we could do the same thing to ourselves.

We’re certainly not the first species to disrupt ecosystems or transform the climate on a global scale. But the threat modern human activity poses—as I have argued before—is different in many ways from the purely natural dangers the planet has faced before. While it may be many years before the next supervolcano or asteroid threatens life on Earth, our activity is a constant, ongoing threat. The danger we represent is not just from climate change or invasive species. It is also from artificial chemicals, genetically-modified organisms, and powerful new weapons. It is a danger neither we nor any other species has a history of surviving.

The truth is that the main threat to humans comes from other humans. Newitz tends to talk about this apparent sixth extinction as if it were a purely natural phenomenon that humans just happened to cause. It’s true that, unlike our predecessor species, we have the ability to anticipate and work together to avert a planetary catastrophe. But it is precisely our technical abilities that make us a such a danger to life on Earth. Right now we are doing as much to endanger ourselves as to ensure our own survival. It is not that much comfort to point out that we’re likely to develop technologies that will minimize the damage we ourselves are causing. The real problem is not that we are powerless, but that much of our power is being used for dangerous ends.

Nevertheless, Newitz is right to focus on what we can do to improve our chances. Sooner or later—and whether or not we are the cause—we will have to live through a global catastrophe. The future of the human race may literally hang on whether we prepare to face disaster. The first thing we need to do is make our civilization sustainable by limiting the damage we do to the environment and weaning ourselves off finite resources. In particular, we need sharply limit our emission of greenhouse gases or we will face serious consequences. Ultimately, she thinks we have to learn to manage the climate well enough to protect ourselves from natural cycles.

But merely working to avoid disaster is not enough. Newitz says we need—as the title of her book says—to be ready to “scatter, adapt, and remember.” Our best hope is to spread out, learn to survive in new environments, and remember what we have learned along the way. In many ways, the efficient division of labor in the modern global economy has made us more vulnerable to disaster. Every part of the world depends to an extent on other parts of the world. In particular, cities—in which most of the world’s population now live—depend on rural areas for necessities. If there were a sudden disruption in global trade, billions of people around the world would struggle to survive. Local communities need to be prepared to survive catastrophe independently of one another. They need to be ready to procure food, water, power, and shelter even if atmosphere becomes toxic or blocks out the sun. And they will need to retain the knowledge it will take to rebuild.

In the longer run, Newitz argues that we can’t keep all our eggs in the single basket of Earth. Like many futurists, her vision is of a human diaspora across the galaxy. As long as our species is confined to one planet—or even one region of space—we remain vulnerable to local disasters.  Others have suggested we start by essentially backing up our planet’s data by building a “biological and historical archive” on the moon. The 100 Year Starship project has begun working toward making it possible to travel to other stars within a century. While it may be a long time before we colonize space, spreading out as widely as possible may be key to the future of the human race.

Newitz is right that we are an extraordinarily adaptable species. But we are also an extraordinarily destructive species. In fact, we are ourselves the greatest threat we have faced in our short history. If our survival were simply an engineering problem, our chances would be good. But, as our ability to affect our environment grows, our survival is increasingly a social problem. Our real challenge—which Newitz doesn’t address—may be to learn to work together as a species. Newitz just hopes that our descendants—whoever or wherever they are—will remember us “as brave creatures who never stopped exploring.” I hope they survive to remember us at all.

Buy Scatter, Adapt, and Remember: How Humans Will Survive a Mass Extinction. Links to books I recommend, review, or cite are Amazon Affiliate links. I receive a small percentage of any purchases made through these links.

(1) Georges Cuvier, Discourse on the Revolutions on the Surface of the Globe and on the Changes They Have Produced in the Animal Kingdom (1825)

(2) Richard Leakey and Roger Lewin, The Sixth Extinction (1996)

(3) Anthony D. Barnovsky et al., “Has the Earth’s Sixth Mass Extinction Already Arrived?” in Nature (March 2011)

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