Humansim overcoats extinction.

Likewise, the Carnian pluvial episode, a smaller mass-extinction event that I’m also fond of and that occurred some 230 million years ago, was so pivotal that the scientists who study this episode describe it as “the dawn of the modern world.” For millions of years, an extremely dry climate had extended across the supercontinent of Pangaea, until an episode of massive volcanism made the planet hotter and much more humid. It rained for about a million years, perhaps in waves that matched the four eruptive peaks of the volcanism. This global wetting led to another profound disappearance of many species, particularly of herbivorous reptiles that had adapted to arid conditions. But on this newly wet planet, a dazzling diversification of more modern coral reefs, conifer trees, dinosaurs, crocodiles, insects, and mammals began. “The origin of modern systems was triggered by the crisis,” Michael Benton, a prominent researcher of this extinction and a professor at the University of Bristol, in England, told me. Extinction is often cast as a destructive force, but in this light, it is also generative. Even in the face of extinction, existing body plans—think of higher taxonomic categories such as phylum, class, or order—rarely disappear entirely. Meanwhile, the environmental changes that drive extinction events also drive the emergence of new body plans, notes the paleontologist Norman MacLeod, a professor at Nanjing University, in China. Extinction also removes the advantages of ecological incumbents—who themselves took advantage of a previous episode of rapid diversification, in many cases after an extinction event—and opens up opportunities for other groups. As a result, extinction has increased the overall range of diversity in the biosphere over time, a phenomenon known as evolutionary stacking. “All these factors underscore the creative role extinction has played in promoting biodiversity,” MacLeod told me. “If there had been no extinction over the course of Earth history, our planet would be home to a far less diverse array of species than it is.” Other than the emergence of new species, extinction is likely the most common evolutionary process on Earth. It is as necessary a part of evolution as death is of life, making space for new species—even whole new ecosystems—to emerge. And this kind of creative destruction is happening constantly: More dramatic events such as the Late Devonian fade into thousands or millions of more everyday extinction events that have made the world as we know it today. Extinction’s beneficent side puts us in an awkward, even discomforting position. The world, after all, is on the upslope of another significant extinction event. Climate change, habitat loss, pollution, and a slew of other environmental problems are radically transforming ecosystems and resulting in a loss of biodiversity unprecedented in the history of our species, according to the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services (IPBES)—the global body of researchers aiming to do for our current crisis of extinction what the IPCC does for climate change. In Earth’s history of extinctions, this one is distinct from all those previous in that it’s clearly caused by us. In the pursuit of our own interests, humans are profoundly reordering every environment on the planet, and extinguishing multitudinous lineages of organisms—the assemblage of species we live alongside. Where does this leave us? Extinction is a tragedy for the species affected, but if we are just the latest in a series of evolutionary pressures, should we then be indifferent? The answer is the intuitive one: We absolutely need to be worried about what humans are doing to the planet. But we should be worried about the transformations we’re causing and all the destruction of ecosystem services that they entail not because extinction is inherently bad, but—first and foremost—because these transformations might well destroy us. Traditional environmental thinking tends to rely on the ideal of preservation to condemn human-driven extinction: Our actions are upsetting a supposed balance of nature that would persist if not for us, so our responsibility is to uphold that balance, guarding or re-creating a version of nature that does not so obviously reveal our influence. “The ravages committed by man subvert the relations and destroy the balance which nature had established between her organized and her inorganic creations,” the diplomat George Perkins Marsh, perhaps America’s first environmentalist, wrote in his 1864 text, Man and Nature—foundational to the conservation movement. More than a century and a half later, this same conceit governs environmental thought. You can see it, for instance, in the way environmental groups and thinkers describe the initiative to reintroduce wolves to Yellowstone National Park: After human actions “ruined” the ecosystem, the wolves were able to “restore balance” by reducing the number of elk in the park. (Never mind that for at least eight years after the wolves returned, humans still killed more elk in the park than they did.) This continuously recurring notion of some harmonious stability ignores the reality of nature’s constant dynamic flux. In trying to preserve an imagined natural balance, many conservationists assume that the current way the world is organized, with its current assemblage of species, is the way that it must always be. Evolution itself disproves that assumption: It has no purpose or direction, and does not end once a given condition is achieved. And any attempt to restore that imagined world in balance has involved making judgments, implicit or explicit, about which species are most worth saving. Beyond the self-interest of maintaining ecosystem services that benefit us, humans can and do have good reasons for trying to save polar bears, pandas, whales, tigers, sea turtles, rhinoceroses, orangutans, penguins, and other charismatic species from disappearing, but those decisions rely on human moral preferences. We have also deliberately eradicated the virus that causes smallpox, and if you accept that as a triumph or protest that those are just microbes, then you accept that not all species have an equal right to existence: that whales and orangutans—and people—are more important than bacteria and viruses. In many ways, fidelity to the idea that humans upset nature’s balance holds us back from addressing the perils of extinction. The conservation biologist Mark Vellend worries, for instance, that counts of biological diversity disregard new species in novel, human-influenced ecosystems—where extant species occur in new combinations or abundances. He gives the example of New Zealand. Since humans arrived, some three-quarters of that country’s forest has been converted for their use, a sizable chunk of all endemic birds have gone extinct, and non-native species have multiplied. But in that same period, he says, the number of plant species has doubled, the number of bird species overall has stayed roughly the same, and dozens of land mammals have moved in where none had lived. So is New Zealand an example of a biodiversity crisis, or a biodiversity success? Vellend and others stress that this doesn’t mean global biodiversity is doing fine. Rather, it indicates that the erroneous belief that evolution follows a particular direction may be skewing our assessment. And if we do want to maintain, more or less, the current global assemblage of species—the assemblage to which we humans are adapted—then scientists need to be able to measure it accurately.