When alien archeologists dig through the rubble of our cities and survey our planet’s ravaged lands and waters, searching for clues to the global catastrophe that wiped out half the species on Earth, what will they notice? The carbon-charged atmosphere, the layer of radioactive debris, a worldwide taint of manufactured poisons, vast middens of rubbish marking abandoned settlements, a scum of plastic on the oceans, bleached corals, oil-saturated wetlands, drained aquifers, silted reservoirs, craters from exhausted mines, and forests reduced to cemeteries of stumps. What a waste, the aliens will think, to ransack a planet so well-suited for life. Belonging to a species wise enough to avoid trashing their own home, they will sift through the ruins to puzzle out what might have given rise to all these disorders, and they will find the answer in troves of printed matter—contracts, invoices, spreadsheets, blueprints, military budgets, chemical formulas, stock market reports, advertising flyers, shopping lists, medical prescriptions, and real estate maps—in short, what they will discover at the root of this global havoc, the technology that made it all possible, is writing.

As you might guess, I summoned these alien archeologists from a distant galaxy, speeding them through a handy wormhole in space, in order to express my worst fears about the human impact on Earth. Since I have devoted my life to reading and teaching literature, and adding my own minor works to the world’s library, I wish I could have blamed the ravaging of our planet on some other technology, such as money, gunpowder, the internal combustion engine, nuclear reactors, antibiotics, or the internet. But when I considered how humans have managed to spread our population into every habitat around the globe, alter the chemistry of Earth’s atmosphere, pillage and poison its oceans, squander its arable soils, and exterminate incalculable numbers of our fellow creatures, I realized that none of these upheavals could have occurred had our ancestors not invented writing.

By writing, I refer to visible marks that convey meaning, not only for the person making the marks but also for those who view them. Such marks began to appear as pictures carved or painted on the walls of caves and the faces of cliffs as early as 30,000 years ago; then around 5,500 years ago they appeared as wedge-shaped indentations in clay tablets, and later on as scratches incised into ivory and turtle shells and bone, as inky scrawls on papyrus and vellum, as print on paper in scriptures and dictionaries and laws, eventually as words displayed on every surface from billboards to smartphone screens, and most recently as ghostly zeroes and ones inscribed on magnetic disks.

According to scholars, the practice of writing emerged independently in at least four locations—ancient Mesopotamia, Egypt, China, and Mesoamerica—in each place amid increasing social complexity brought on by the rise of cities and empires. In light of these multiple origins, it would appear that the making of durable marks to signify objects, ideas, and the sounds of speech was a natural, perhaps inevitable, next step in the evolution of human language.

What uses did the earliest writing serve? To keep track of trade goods (sheep, barley, and beer were major items); to proclaim the exploits of tyrants (lands conquered, slaves captured); to record taxes and tributes (paid chiefly to potentates and priests); to relate stories about capricious and often violent gods (and methods for divining their purposes); to chart the movement of sun, moon, planets, and stars (in order to align planting, hunting, ritual sacrifice, and other activities with the wheeling cosmos). All these millennia later, writing serves us in countless additional ways, from crossword puzzles to musical notation, love letters to recipes; but the earliest uses of writing persist today, vastly expanded, in business, government, religion, and science—the realms of human endeavor that have enabled us to dominate and devastate the planet.

Without the invention of writing, our species might well have survived into the twenty-first century, as we had survived for tens of thousands of years with only spoken language; we might still be making tools out of wood and stone and bone, baskets out of reeds and bark, canoes and snowshoes and any number of other useful objects; we might be foraging and farming, studying the stars, and telling stories around the fire. But we would not be making nuclear weapons, computers, or plastic. We would not be spraying herbicides on 5,000-acre fields of genetically modified soybeans while riding in satellite-guided tractors weighing 15,000 pounds. We would not be flying across oceans in air-conditioned aluminum tubes, spewing soot, metal particles, and planet-heating carbon compounds in our wake. We would not be clear-cutting the Amazon rainforest, nor blasting the tops off mountains in search of cheap coal, nor drilling for oil in the oceans. We might still be fighting religious wars, but they would not be justified by quoting passages of scripture recorded thousands of years ago. Lacking antibiotics, antiseptics, vaccines, laser surgery, and the whole toolkit of modern medicine, our population would more likely be numbered in the millions than in the billions, but countless other creatures, now endangered or extinct, would be flourishing.

Without writing, it is unlikely that the ancient Greek word anthropos would have survived into the twentieth century to prompt a scientist (there is disagreement about precisely which scientist) to coin the term Anthropocene as a name for the geological era succeeding the Holocene. Some critics of the term regard it as a form of bragging, exalting the importance of our lone species. But rather than seeing the label as a boast, I take it as an acknowledgment of culpability. Unlike the phenomena that brought about earlier mass extinctions—asteroid impacts, volcanic eruptions, the oxygenation of Earth’s atmosphere by cyanobacteria, and extreme shifts in global temperatures and sea levels—humans are conscious creatures, with the capacity to understand the dire effects of our actions and, in light of this knowledge, to change our ways. The alien archeologists have investigated disasters on many other planets, but never one brought about by a single species so amply warned of its folly.

In spite of my fears, I recall that those warnings come to us chiefly through writing. They come to us in scientific reports, editorials, journal articles, petitions, essays, poems, novels, graphs, and written messages on all our screens. So the invention that has enabled us to hurtle toward global catastrophe might also inspire us to avoid it. If I did not believe in that possibility, I would not have written this little fable to share.