The Third Chimpanzee

How did we, ordinary apes from Africa, come to dominate the entire planet—and possibly doom it in the process? In The Third Chimpanzee, Jared Diamond argues that humans are essentially the third species of chimpanzee, separated from our ape cousins by a surprisingly small genetic difference but set apart by a colossal behavioral leap. What distinguishes our species most, he contends, is not anatomy or intellect alone, but the cultural and evolutionary forces that gave rise to language, art, agriculture, and conquest—traits that have allowed us to shape the world, for better and for worse.

Drawing from anthropology, evolutionary biology, archaeology, and ecology, Diamond paints a sweeping portrait of humanity’s rise. He shows how tiny changes in our DNA produced language and creativity, how sexual selection shaped our racial and social diversity, and how our unique cultural powers unleashed both civilization’s grandeur and its self-destructive tendencies. Our capacity for cooperation and imagination made us the planet’s rulers—but also its greatest threat, capable of environmental collapse or nuclear annihilation.

From Ape to Human: Evolution’s Smallest Gap

Diamond begins with the genetic evidence: humans share over 98 percent of our DNA with chimpanzees. We are, in his phrasing, just one of three chimpanzee species—the common chimp, the bonobo, and us. What made us different wasn’t a gigantic leap in biology but a subtle reconfiguration of the brain, perhaps a mutation that enabled fine muscle control of the tongue and larynx. This adaptation unlocked language, which in turn unlocked cooperation, planning, and imagination. From this capacity, every distinctly human triumph, from cave paintings to space stations, eventually flowed.

(Diamond’s argument echoes ideas later popularized by Yuval Noah Harari in Sapiens: that language and storytelling allowed Homo sapiens to organize in vast groups and create shared myths. Both authors see language as evolution’s game-changer for social intelligence.)

The Great Leap Forward

Roughly sixty thousand years ago, something happened that transformed anatomically modern humans into behaviorally modern ones—a “Great Leap Forward.” Diamond describes this as the moment when our ancestors began creating art, tools, and trade networks, while their close cousins, the Neanderthals, faded into extinction. He credits this leap to the birth of true language, which not only let humans coordinate and plan but also imagine—the power to conceive tools before building them and to dream of gods before painting them on cave walls.

This shift turned us into an inventive species capable of cumulative culture. Before the Leap, stone tools changed little for a million years. Afterward, technology and art exploded: bone needles, flutes, ivory figurines, and sprawling cave murals, such as those at Lascaux, appeared. The human revolution had begun.

The Double-Edged Sword of Progress

Yet Diamond insists that our evolutionary gifts have brought peril as well as progress. Every human breakthrough—from spreading across continents to mastering agriculture—has come with unintended consequences. Humans wiped out megafauna on every continent they entered. Farming fed populations but also spawned disease, inequality, and environmental degradation. Our intelligence allows extraordinary cooperation but also industrial-scale killing: genocide, ecological collapse, and nuclear war. We are the only species that threatens its own mass extinction through its inventions.

An Interdisciplinary Map of Humanity

Across the book, Diamond moves from the micro to the macro—from genetic mutations to global civilizations. Part One (“Just Another Big Mammal”) explores our origins, the Great Leap Forward, and the biological roots that tether us to our primate cousins. Part Two (“A Strange Life Cycle”) delves into human sexuality, racial diversity, and why we age. Part Three (“Uniquely Human”) examines our crowning cultural inventions—language, art, agriculture, and technology—and their dangerous offspring, such as drug addiction and environmental destruction. Finally, in “World Conquerors” and “Reversing Our Progress Overnight,” Diamond confronts our darker side: colonial conquest, genocide, and the risk of self-annihilation through pollution or war.

Through case studies—from the extinction of New Zealand’s moas to the genocide of Tasmania’s indigenous people—he shows humanity’s recurring pattern: rapid expansion followed by ecological or moral catastrophe. These cycles raise the haunting question of whether intelligence itself is a fatal adaptation.

Why It Matters Now

Diamond’s message resonates more urgently today than when he first wrote the book in the early 1990s. As climate change, nuclear tensions, and biodiversity loss intensify, his observation that we live under “two clouds”—nuclear war and environmental collapse—rings prophetic. He challenges us to confront our evolutionary inheritance: our brilliance at innovation and equal brilliance at self-destruction. Understanding our past as the “third chimpanzee” may be the only way to ensure we don’t become the last one.

Ultimately, The Third Chimpanzee is a mirror held to humanity: it shows how a slightly smarter ape built civilizations and symphonies, but also weapons and wastelands. Diamond’s challenge to you, the reader, is simple yet profound—can our species use its intelligence to save itself, or will our story end like that of so many others we’ve wiped from the earth?

Diamond calls the transition to full behavioral modernity the “Great Leap Forward”—a tipping point around 60,000 years ago when Homo sapiens began to act, think, and create in ways that no other species, not even the Neanderthals, ever had. This leap, he suggests, was not a gradual evolution but a relatively sudden burst, sparked by something invisible to the fossil record: the birth of complex language.

From Stone Tools to Symbolic Minds

Early humans like Homo erectus and Homo habilis had made tools and walked upright, but their technology remained static for nearly a million years. Fossils show they had large brains—yet those brains didn’t translate into innovation. Then, seemingly overnight in evolutionary terms, anatomically modern humans began painting animals on cave walls, sculpting figurines, burying their dead with ritual, and inventing new toolkits with specialization and artistry. Something fundamental had changed in the way the human mind worked.

Diamond points to language as the critical catalyst. With language came the capacity for planning, teaching, and imagination—for sharing knowledge across generations. Speech allowed humans to build mental models, brainstorm solutions, and coordinate complex group activities such as hunts or migrations. Language turned isolated intelligence into collective intelligence.

The Fall of the Neanderthals

The Great Leap Forward was also the death knell for the Neanderthals. Diamond portrays their extinction not as a tragic accident but as an early example of Homo sapiens’s competitive advantage—and perhaps brutality. When modern humans entered Europe around sixty thousand years ago, they soon displaced (or annihilated) the resident Neanderthals. Genetic evidence shows that limited interbreeding occurred, but the Neanderthals vanished soon after. Diamond likens their fate to that of indigenous populations facing advanced colonizers in later history: technologically outmatched, they were doomed.

(This echoes later themes in Guns, Germs, and Steel, where Diamond shows how technological inequality—not racial superiority—explains conquest. The Great Leap offers the evolutionary prototype for that inequality.)

Language as the Hidden Mutation

The origins of this linguistic explosion may lie in a tiny genetic shift—a mutation affecting the human larynx and tongue, enabling fine control of vocal sounds. Apes can use symbols and gestures, but their vocal anatomy limits speech. Once our ancestors could produce diverse sounds, the selective advantage of talking—and of understanding talkers—multiplied. Those who could communicate better could hunt better, teach better, and survive better. The gene for language became humanity’s master key.

This breakthrough transformed how culture evolved. Before the Great Leap, change depended on slow genetic evolution. Afterwards, it depended on cultural evolution—ideas passed from mind to mind at lightning speed. That shift, Diamond argues, marked the dawn of history in all but name. From art to agriculture, everything else humanity has done stems from that small but world-shaking mutation.

Diamond opens the book with a warning: for the first time in history, one species—us—faces two existential threats of its own making. One is sudden and obvious: nuclear war. The other is slow and often denied: environmental collapse. Both could end civilization, but only the second is already underway.

Cloud One: The Nuclear Shadow

The first cloud appeared in 1945 over Hiroshima. The atomic age proved that humans now had the power to destroy all life on Earth in a single catastrophic act. The potential for miscalculation, hubris, or political insanity became an enduring feature of civilization. Yet ironically, the very horror of nuclear war also spurred global diplomacy and restraint—it became the apocalypse we could imagine vividly enough to fear.

Cloud Two: The Environmental Time Bomb

The second cloud—mass extinction and ecological collapse—descends more quietly. Diamond argues that humans have been driving species to extinction for tens of thousands of years, beginning with prehistoric hunters who wiped out megafauna around the world. What began as overhunting accelerated into habitat destruction, species introductions, and ripple effects that now threaten entire ecosystems. The loss of tropical rainforests and the accelerating extinction rate—“two hundred times faster than natural levels”—prove that we’ve become a geological force unto ourselves.

He illustrates this with vivid case studies: the vanished moas of New Zealand hunted by Maori settlers; Madagascar’s lost elephant birds; and the catastrophic deforestation of Easter Island, where the people who erected its famous statues eventually starved in a desolate landscape stripped of trees. Each serves as a parable for our modern world—a civilization advancing to greatness while sawing away the ecological branch it stands on.

Ripple Effects and Ignorance

Diamond warns that ecosystems are complex, interconnected “rows of dominoes.” Knock down one, and others fall in unpredictable sequence. On Panama’s Barro Colorado Island, the removal of big predators like jaguars and harpy eagles set off a cascade: mid-sized predators exploded in number, wiping out smaller birds and changing the composition of the forest. The lesson is that we don’t understand enough to dismantle nature safely. Extinction isn’t a single tragedy—it’s a chain reaction.

For Diamond, the choice ahead is existential. Unlike the nuclear threat, which may never strike, the environmental one is already here. He asks whether wisdom can keep pace with power—whether the species that conquered every habitat can learn at last to preserve the only one it has left.

We often imagine agriculture as humanity’s greatest step forward—a triumph that lifted us from the misery of hunting and gathering into comfort and culture. Diamond dismantles that myth. In one of the book’s most provocative chapters, he calls farming “the worst mistake in the history of the human race.”

The Allure of Farming—and Its Lies

At first glance, agriculture seems an obvious improvement: more food, more people, more leisure. But Diamond marshals archaeological evidence showing the opposite. Studies of ancient skeletons from Greece, Turkey, and the Americas reveal that early farmers were shorter, sicker, and more malnourished than the hunter-gatherers they replaced. Cavities, bone infections, and anemia skyrocketed with the spread of grain-based diets. The diversity and protein of wild foods gave way to starchy monotony—rice, wheat, or corn.

He argues that agriculture didn’t end hunger; it institutionalized inequality. For the first time, it allowed elites to hoard food, while others toiled. Class division, disease, and overpopulation—all hallmarks of civilization—were born in the fields and granaries. Even art and architecture, Diamond notes, owe their existence to surplus food—but so do armies and empires. The pyramid rose on the bodies of peasants.

The Cost of a Monoculture

Agriculture also bound humans to fragility. Hunter-gatherers, eating diverse plants and game, could survive when one resource failed. Farmers put their fate in a few crops—and when those crops failed, famine followed. The Irish Potato Famine of the 1840s, when a blight wiped out the island’s primary food source and killed a million people, is only a modern echo of that ancient vulnerability.

Crowds, Contagion, and Class

Living close to crops and livestock brought plagues that hunter-gatherers never suffered: smallpox, tuberculosis, cholera, and influenza. Domesticated animals were humanity’s Trojan horses for disease. Villages turned into breeding grounds for infections—and for social hierarchies. Skeletons from ancient Greece show stark differences: royals were taller and healthier than peasants buried nearby. Agriculture created enough food to support non-farmers—kings, soldiers, and priests—but not enough equity to feed all well.

Agriculture was a revolution, but not a moral one. It gave us culture, cities, and art—but also epidemic disease, environmental ruin, and inequality. It was humanity’s original Faustian bargain: trading freedom and health for the illusion of plenty.

Why do humans kill one another in mass numbers? Diamond argues that genocide is not an aberration of history, but a continuation of our animal instincts amplified by technology and ideology. From Tasmania to Nazi Germany, mass killing has recurred whenever power, fear, and dehumanization align.

A Species That Kills Its Own

Diamond dismantles the comforting myth that only “monsters” commit genocide. Through case studies—especially the extermination of Tasmania’s indigenous people by British settlers—he shows ordinary humans turning into killers. The colonists saw the Tasmanians as animals, not peers. Within seventy-five years of first contact, the entire native population was dead. “Civilized” people did not commit genocide despite their progress—they committed it because of their progress.

He then traces the roots of genocide to our evolutionary heritage. In the animal world, chimpanzees engage in coordinated group attacks strikingly similar to human warfare. Jane Goodall watched male chimps plan ambushes against rival troops, murder rivals, and even kidnap females. Violence, Diamond suggests, is not foreign to us—it’s our inheritance.

From Tribal Wars to Modern Slaughter

As societies grew larger, our weapons and justifications became more sophisticated. Religion, race, and ideology expanded the tribal logic of “us versus them.” Whether in the Bible’s account of the Israelites annihilating Jericho or Stalin’s purges of millions, the same evolutionary code applies: protect “our tribe,” dehumanize “theirs.” What changed was scale—technology let us kill at distances beyond empathy. Nuclear weapons and drones are merely the latest tools of an ancient impulse.

Diamond’s analysis strips away illusions: moral codes restrain us, but under stress, tribal instincts resurface. Genocide reveals not humanity’s aberration, but its potential downfall—the moment when our intelligence merely refines our primal disease.

Where do racial differences come from—evolutionary necessity or human preference? Diamond takes on one of the most controversial questions in science and argues that sexual selection—not just natural selection—crafted our physical diversity.

Beyond Survival: Beauty as Evolution

Natural selection explains much: dark skin protects against sunburn near the equator, and stocky bodies conserve heat in cold climates. But these factors alone can’t explain the vast palette of human skin, hair, and eye colors. Why do some Australians have blond hair despite intense sunlight? Why do blue eyes cluster in cold Scandinavia? The answers, Diamond suggests, lie not in adaptation but attraction: who we find beautiful.

Following Darwin, he argues that once survival needs were met, mate choice became evolution’s artist. People preferred those who looked familiar—traits common in parents and peers. Over generations, these preferences intensified local differences, leading to distinct “races.” Just as peacocks evolved bright feathers to please peahens, humans evolved visible traits to please each other.

Racial Diversity as an Accident of Taste

In effect, racial features are the evolutionary equivalent of fashions frozen over millennia. Imprinting—the process by which early experiences shape preferences—locked communities into cycles of beauty bias. A society that prized pale skin or curly hair would reproduce those traits not because they helped survival, but because they appealed to desire. What we call “race,” Diamond suggests, is largely a product of ancient aesthetics, not destiny.

This reframing demystifies race without denying human variation. The same evolutionary process that made a peacock’s tail also made human diversity. The tragedy, Diamond hints, is that we’ve turned those aesthetic differences into hierarchies of worth—a cultural, not genetic, flaw.

Diamond closes The Third Chimpanzee not with despair but with cautious hope. Humanity’s record is grim—we’ve exterminated species, cultures, and sometimes ourselves—but we are also uniquely capable of learning from our past.

Learning from Collapse

History, Diamond writes, is full of warnings. Civilizations that destroyed their environments—like the Anasazi of the American Southwest or the Easter Islanders—fell not from stupidity but from shortsightedness. They lacked models for sustainability. We, however, have those models, preserved in the few societies that lived within their limits. By studying them, we can avoid repeating “nothing learned, everything forgotten.”

The New Choice

Unlike our ancestors, we can see the global consequences of our actions in real time. We have science, communication, and a shared awareness that no previous age possessed. If our intelligence once served destruction, it can now serve preservation. Our history as conquerors can become a guidebook for survival—if we choose to heed it.

In that recognition lies hope. The third chimpanzee has walked a perilous path, but the very curiosity that drove it to explore—and exploit—may yet save it. Our survival, Diamond concludes, depends on whether we can finally unite the ape’s cunning with the wisdom of reflection.