Mass Extinctions: The Five Times Earth Nearly Died

Five mass extinctions. Billions of years of evolution. Entire species wiped from existence. And one disturbing question: Are we living through the next one? In 1796, a young French anatomist named Georges Cuvier examined the fossilized remains of mammoths and mastodons and reached a conclusion that challenged everything scientists thought they knew about the natural world: entire species could disappear forever.

Even Thomas Jefferson resisted the idea, holding out hope that living mammoths might still roam the unexplored American wilderness.More than two centuries later, we know Cuvier was right. The history of life on Earth is filled with catastrophic extinction events that erased entire ecosystems, transformed the planet, and fundamentally changed the course of evolution.

In this episode of Disturbing History, Brian investigates the terrifying science behind Earth's Big Five mass extinctions, the discoveries that revealed them, and the growing scientific debate over whether humanity is triggering a sixth.Our journey begins with a thin layer of ancient clay containing an unusual concentration of iridium. That discovery led scientists Walter and Luis Alvarez to propose that an enormous asteroid struck Earth 66 million years ago, setting off the catastrophe that ended the reign of the non-avian dinosaurs. The evidence would eventually lead researchers to the massive Chicxulub impact crater beneath Mexico's Yucatán Peninsula.But the dinosaur extinction was only one chapter in a much darker geological history.

Brian explores all five of Earth's great mass extinctions, from the devastating ice age that emptied ancient oceans during the Ordovician to the mysterious collapse of marine ecosystems during the Devonian. We examine the Great Dying, approximately 252 million years ago, when catastrophic volcanic activity in Siberia helped unleash the deadliest known extinction in Earth's history, eliminating an estimated 81 to 96 percent of marine species. We also uncover how massive volcanic eruptions at the end of the Triassic helped clear the evolutionary path for dinosaurs to dominate the planet. Then the story takes an even more disturbing turn.

What happens when the force driving extinction isn't an asteroid, an ice age, or a volcanic catastrophe—but us? From the last surviving woolly mammoths on Wrangel Island to the disappearance of the dodo and Steller's sea cow, Brian examines how human expansion, relentless hunting, and habitat destruction helped drive