Definition
The megafauna extinction is the global pattern, between roughly 50,000 and 10,000 years ago, in which the largest land animals on every continent except Africa disappeared within a few thousand years of the arrival of Homo sapiens. Australia lost giant kangaroos, diprotodons, marsupial lions, and flightless birds soon after Sapiens reached it around 45,000 BCE. North and South America lost mammoths, mastodons, ground sloths, sabre-toothed cats, and dozens of other large species after Sapiens crossed Beringia. New Zealand lost the moa, and Madagascar lost the elephant bird, in historical times.
Harari treats this pattern as the first topic in the long story of Sapiens' ecological footprint. Long before agriculture, long before industry, foragers with stone tools were already capable of reshaping continental ecosystems.
Why it matters
How it works
The mechanism is slow-burn over-hunting compounded by ecosystem disruption. A long-lived, slow-reproducing species like a mammoth cannot tolerate sustained predation pressure. Sapiens with spears and fire imposed exactly that pressure, and unlike resident predators they were generalists, so they did not collapse when their prey did. They simply switched to the next species down.
That is why Africa is the partial exception. African megafauna co-evolved with hominin hunters over millions of years and adapted to wariness. The Australian, American, and Eurasian megafauna had no such evolutionary preparation and met Sapiens cold.