Today, with the accelerating number of species being driven to extinction by human activities, many scientists have begun talking about a sixth mass extinction. The loss of species over the past 150 years has been dramatic, to be sure. Fortunately, so far, the rate has not risen to the level of the Big Five. To convince yourself of this, picture your favorite bit of landscape, and then imagine half of the life you see suddenly blinking out. We’re not there yet. We do, however, run a high risk of getting there, given the increasing pressures of human population growth, habitat destruction, pollution, damaging invasive species, and climate change. Should we be worried? Yes, we should.

In the Washington Post piece, Pyron seizes upon dramatized expressions of concern regarding the morality of human-caused extinctions and dismisses them with a false argument: the claim that extinction is essential for evolution (as well as the idea that evolution ultimately repairs the damage of extinction). His statement that “extinction is the engine of evolution” is particularly curious and decidedly wrong. Scientists think of evolution as a cycle with three main stages. First, there is the generation of variation through mutation, which occurs every time DNA is copied throughout the life span of cells and whole organisms, as well as through the recombination of genes when organisms reproduce sexually. Second, there is selection of that variation, whereby individuals that are better adapted to the environment have greater odds of surviving and reproducing offspring that carry their genes. Third, the products of this selection interact with their environment, thereby affecting the outcome of future selection events. Where is extinction in this cycle?

Pyron seems to subscribe to the notion that extinction makes room for new species to succeed by wiping away the old, calling extinction “the mechanism by which natural selection prunes the poorly adapted and allows the hardiest to flourish.” He isn’t the first to espouse this erroneous view; it’s quite common for science communicators to frame the mass extinction of the dinosaurs 66 million years ago as an event that made room for the rise of mammals. Natural selection does indeed prune poorly adapted individuals, but that’s evolution driving extinction, not the other way around. New species evolved continuously in the past, whether or not the rate of extinction was high. In fact, there are times in the fossil record when the production of new species accelerated with no accompanying change in extinction. The coincidence between mass extinctions and the rise of new types of species has less to do with making room on the planet, and more to do with changing environments and ecologies.

The dichotomy between “poorly adapted” and “hardiest” is also a misconception about evolution and a dangerous throwback to social Darwinism. A quote of uncertain origin that is often wrongly attributed to Charles Darwin puts it best: “It is not the strongest of the species that survives, but rather, that which is most adaptable to change.” There are no poorly adapted species today; nor are there hardiest or strongest ones. Every species alive today is very well adapted to its environment. We are causing that environment to change, and the species that can adapt to the changes will survive. If we can slow the rate of change, more species will survive—it’s that simple.

On the subject of ecology, we come to the most dangerously misguided of Pyron’s arguments: that the extinction of a species hardly matters—to humans or to the rest of the natural world. Refuting this argument starts with a critical look at another cliché: the idea that all life is connected. While it’s true that all living organisms are ultimately connected, the importance of individual connections varies greatly, and many are probably not critical to a species’ survival. Nevertheless, there can be thousands of connections among organisms—tens of thousands in diverse communities such as coral reefs and rainforests. And because there’s still so much that we don’t know about most of these interactions, it’s irresponsible to make flippant conclusions about which connections or species are important to others and which are not.

What we do know is that some species and connections are critical to the survival of other species and, perhaps more crucially, that changes to ecosystems tend to be highly nonlinear. What that means, essentially, is that dependencies in the web of life are unpredictable. The effects of changes to ecosystems do not add up in a neat and orderly fashion, precisely because some components are more important than others. There are tipping points in those systems, and we hardly know where most of them are.

Much of the resilience of modern societies has been built upon reliable natural dependencies, such as a predictable climate, clean water, and clean air. Our planet produces those conditions not by magic, but by processes, and our increasing alteration of those processes threatens to erode the resilience of our own societies.

Contrary to Pyron’s rash assessment, there are plenty of self-serving reasons for our species to care about preserving biodiversity as broadly as possible. But there are also other reasons to object to his suggestion that we needn’t bother protecting species that offer no direct benefit to humans. Pyron argues that the inevitability of death and extinction essentially excuses sitting idly by while countless species drop off the face of the Earth—many due to our own actions. It’s hard to see, though, how an argument like this holds up when viewed in the context of our own existence. Despite the fact that every one of us will eventually die, we still seek out and benefit from doctors, hospitals, and schools—not to mention art, music, and sports. Why bother? The answer, of course, has to do with the quality of the lives we lead while we’re here on this Earth.

Species richness not only provides innumerable ecological benefits, it also simply makes our lives richer. Even if we could identify all of the species that provide no benefit to us today or in the foreseeable future, that doesn’t mean we should feel okay about watching as they’re erased from existence. How pleasant would a world be with only domesticated animals and crops? Or a world with mangrove forests, preserved to protect coastlines from storm surges, but devoid of mangrove crabs, and snakes, and scarlet ibises? Probably not unlike a world without art, music, and sports. Although most people have probably never seen or heard of the golden snub-nosed monkey (Rhinopithecus roxellana) or the Malabar pufferfish (Carinotetraodon travancoricus), the loss of these endangered species would be akin to the destruction of precious works of art.

We agree with Pyron that part of the solution must be moderation for the sake of sustainability. But science must provide honest and informed recommendations about what forms that moderation should take. And science must be the foundation of sustainable solutions that satisfy the diverse needs and interests of our global society—a society that cannot be removed from biodiversity. When it comes to extinction events, human civilization and its environmental impacts currently stand somewhere between a Siberian super volcano and a massive asteroid, neither of which left a pleasant planet in its aftermath. The difference between us and those natural events is that we are also gamblers in the casino. And we can still choose to walk away with our winnings.

All images ©Joel Sartore/National Geographic Photo Ark