The farther from Africa, the more giant animals vanished
In the Late Pleistocene about 65 percent of the world's large animal species died out. The losses were milder in Africa and South Asia and worst in Australia and the Americas, the regions modern humans reached last. That pattern sits at the heart of a long argument over whether people or climate were to blame.
Megafauna usually means animals of 45 kg or more, and these extinctions targeted them with unusual precision. Small creatures came through largely unscathed, while around 80 percent of mammals above 1,000 kg disappeared worldwide, including every one of them in Australia and the Americas. Nothing evolved to fill the vacated roles, so whole ecosystems shifted into new states.
Timing varied by region. Australia and New Guinea started losing species some 50,000 years back; the Americas followed roughly 13,000 years before the present. Both waves line up with the arrival of modern humans. In the Americas the die-off took 3,000 years at most, while in northern Eurasia it was spread across tens of thousands of years, with warm-adapted species such as the straight-tusked elephant going before cold specialists like the woolly mammoth.
Two explanations compete. One blames shifting ice sheets shrinking good habitat; the other, called overkill, blames human hunting. Islands offer striking support for the second: mammoths hung on at remote Wrangel Island for 6,000 years after vanishing from the mainland, ground sloths outlasted their continental relatives in the Antilles, and Steller's sea cow survived off the uninhabited Commander Islands, each disappearing later, when people finally arrived. Genetic studies of surviving species add that climate alone fails to predict population declines over the past 75,000 years, pointing to humans as the main driver from about then.
The case is not closed. The dating of Australia's extinctions remains ambiguous, and many researchers argue that climate, competition, fragile populations and hunting combined, with species reacting differently. Africa's more limited losses near the end of the epoch seem mostly climate-driven, tied to changing grasslands.
Source: Late Pleistocene extinctions
