The Decline and Fall of the Human Empire: Science Writer Henry Gee Argues Homo Sapiens is on a Rapid Path to Extinction

Since the beginning of geological time, biological species have continually risen to dominance on planet Earth, only to eventually fade, fracture, and fall into oblivion. The narrative of life is one of endless transition. Had a freak asteroid not collided with the Earth some sixty-six million years ago, bringing a catastrophic and abrupt halt to their reign, the time of the dinosaurs as the supreme animals on the planet would have eventually faded anyway. Now, award-winning science writer Henry Gee turns his critical eye toward the current masters of the planet in his newly released paperback book, The Decline and Fall of the Human Empire. In this concise, brilliantly told history of our species, Gee argues that modern humans are on a rapid, one-way trip toward ultimate extinction—though conscious, urgent steps might still be taken to delay that inevitable fate for a short while.

The Enduring Shadow of the Dinosaurs

To understand the trajectory of human existence, Gee begins by examining how humanity views the prehistoric past, noting that of all the animals that have risen and fallen throughout Earth’s extensive history, it is the dinosaurs that have most thoroughly captured the public imagination. They populate our cinemas, comic books, clothing lines, and school lunchboxes. The word "dinosaur" carries such immense cultural cachet and pulling power that it is frequently deployed to sell products that have virtually nothing to do with prehistoric creatures at all.

Popular books on ancient life are routinely titled Dinosaurs, followed by a smaller, apologetic subtitle reading and Other Prehistoric Animals. Toy sets featuring plastic dinosaur models often include creatures that lived during the same era but were not actually dinosaurs—such as flying pterosaurs or swimming plesiosaurs—and occasionally even throw in Dimetrodon, a toothy, sail-backed creature that lived tens of millions of years before the dinosaurs and is phylogenetically more closely related to mammals. Retailers might even include a woolly mammoth, an animal that roamed the Earth more than fifty million years after the dinosaurs vanished.

This near-synonymy of "dinosaur" with ultimate extinction and clickbait fascination underscores humanity’s obsession with things that fall from grace. Dinosaurs appeared to be thriving right up until the very end of the Cretaceous Period, roughly sixty-six million years ago, when they suddenly disappeared alongside pterosaurs, plesiosaurs, and truck-tyre-sized ammonites.

Debunking the Myth of Orthogenesis

For decades, the precise reason why dinosaurs perished was a non-question that attracted a staggering wealth of speculative answers, with more than a hundred theories cluttering the fringes of scientific literature. Theories ranged from fragile eggshells and newborn-crushing shells to overzealous mammals eating their eggs, indigestion from newly evolved flowering plants, debilitating hay fever, contagious diseases, excessive body weight, declining reproductive rates, and sheer boredom—a condition that acquired the technical term Palaeoweltschmerz.

The most outrageous idea—that the world was struck by an enormous asteroid whose impact ushered in an interval of global catastrophe—ultimately turned out to be the correct one.

Before the asteroid impact theory gained mainstream traction in the 1970s, many scientists subscribed to the notion of "racial senescence," or "orthogenesis." This archaic concept posited that after a hundred million years of tenure, dynasties of creatures naturally became outmoded, tired, and worn out. Under this framework, the Devonian Period was the "Age of Fishes," which naturally gave way to the "Age of Amphibians," followed by the "Age of Reptiles" and finally the "Age of Mammals," culminating inevitably in Man.

In this outdated view, dynasties of animals arrived, supplanted existing ones, and were in turn eclipsed when their time was simply up. The word "dinosaur" became a cultural synonym for something massive, obsolescent, and entirely unsuited to the modern world, much like manual typewriters or discontinued automobiles.

However, the pioneering work of palaeontologist John H. Ostrom and his student Robert Bakker helped reinvent dinosaurs as warm-blooded, dynamic creatures. Combined with the geological confirmation of the asteroid impact, science realized that dinosaurs were not victims of a natural evolutionary expiration date, but were instead cut down in their prime. If the asteroid had missed, dinosaurs might still be enthroned on Earth today.

The Red Queen and Modern Extinction Dynamics

Orthogenesis was ultimately discarded, replaced by the modern understanding of natural selection. Driven by inherited variation and environmental change, natural selection possesses no memory of the past and no vision for the future. As palaeontologist Leigh Van Valen articulated through the "Red Queen" hypothesis, creatures are locked in eternal competition where predators develop keener weapons while prey evolve greater wariness, requiring species to run as fast as possible just to stay in the same place.

Yet a lingering pattern remained: species and genera consistently appeared, diversified, became dominant, and then faded into extinction. A breakthrough arrived in 2017, when a group of palaeontologists in Helsinki proposed a unifying model. Species rise to dominance by competing with other creatures, much like an irritating grain of sand creates a pearl inside an oyster. Once they reach the top and eliminate their competitors, they enter a long, losing battle against a pitiless, unchanging adversary: the Earth itself. Eventually, the tiny remnant of a dominant group is culled by a chance environmental event. The asteroid was merely a freak catalyst; the dinosaurs would have eventually died out anyway because that is the natural trajectory of living things.

The Solitary Reign of Homo Sapiens

Applying this evolutionary logic to modern humans yields a sobering conclusion: Homo sapiens is marked for extinction. Humans are living creatures and cannot claim any special exemption from the biological rules governing the planet. Yet, humans remain exceptional. In a remarkably short space of time, our species has achieved an unprecedented mastery over nature—penetrating the secrets of atoms, unravelling genetic codes, and scanning the edges of the universe.

Despite these monumental achievements, humanity will inevitably perish, largely because of its own extraordinary success. By becoming so dominant, humans now threaten the very functioning of the ecosystem upon which all life depends. No other single species in Earth’s history has ever posed such a profound threat to its own life support system.

In his previous work, A (Very) Short History of Life on Earth, Gee introduced the Karenina Principle, observing that while all thriving species are alike, each species on the brink of extinction meets oblivion in its own unique way.

According to the principles established by the Helsinki research group, the inevitable demise of Homo sapiens was sealed the moment it became the absolute last human species standing. For most of its history, our species shared the planet with evolutionary cousins. Up until roughly 50,000 years ago, Neanderthals roamed Europe and northern Asia, Denisovans inhabited central and eastern Asia, Homo erectus lingered in Java, and dwarfed hominins such as Homo luzonensis and Homo floresiensis lived in island Southeast Asia.

However, by roughly 25,000 years ago, coinciding with the harshest snap of the last ice age, Homo sapiens had colonized Africa and Eurasia, driving all other human species to extinction. From the moment the last non-sapiens human drew its final breath, the card for our own species was marked.

Beneath the veneer of progressive global domination, Homo sapiens has been living on borrowed time for millennia and now stands near a precipice. In The Decline and Fall of the Human Empire, Henry Gee explores the mechanics of this impending collapse while outlining how humanity might—if it proves sufficiently wise, lucky, and ingenious—evade its fate for a little while longer. For those currently alive, Gee emphasizes that humanity finds itself at a unique and critical turning point in the long history of the species.