Five Catastrophes That Reshaped Life
Over the past 540 million years, five mass extinction events have each eliminated more than 75% of all species on Earth. These catastrophes — caused by volcanic mega-eruptions, asteroid impacts, glaciation, and ocean chemistry changes — fundamentally redirected the course of evolution. Without the End-Cretaceous extinction 66 million years ago, dinosaurs would likely still dominate, and mammals might never have diversified beyond small, nocturnal forms.
The Great Dying
The End-Permian extinction (252 Mya) stands alone as the most devastating event in the history of life. The Siberian Traps volcanic province erupted for roughly a million years, releasing enough CO₂ to warm the planet by 8-10°C. Oceans became acidic and anoxic, hydrogen sulfide poisoned the atmosphere, and roughly 96% of marine species and 70% of terrestrial vertebrate species perished. The simulation above visualizes this and the other four major events on a zoomable timeline.
Recovery and Adaptive Radiation
Mass extinctions are followed by adaptive radiations — bursts of speciation as surviving lineages diversify to fill empty ecological niches. After the Cretaceous extinction, mammals evolved from small generalists into whales, bats, primates, and hundreds of other forms within just a few million years. The speed of recovery depends on the severity of the environmental disruption: the End-Permian recovery took 10-15 million years, while post-Cretaceous mammalian diversification was well underway within 1-2 million years.
The Sixth Extinction?
Current species extinction rates are estimated at 100 to 1000 times the normal background rate, leading many scientists to argue that a sixth mass extinction is underway. Unlike previous events driven by volcanism or asteroid impacts, this one is driven by a single species: Homo sapiens. Habitat destruction, climate change, pollution, and invasive species are the modern equivalents of the Siberian Traps. Whether we can prevent this extinction from reaching Big Five magnitude is one of the defining challenges of the 21st century.