371 | Kyle Harper on How Humans Have Shaped Life on Earth

The dodo wasn’t simply hunted to extinction by hungry sailors. The real culprit was the retinue of animals that came with them—rats, pigs, cats, and monkeys—that ate the dodo’s eggs and destroyed its habitat. That story, told by historian Kyle Harper on Sean Carroll’s Mindscape podcast, captures a central argument of his new book The Last Animal: human beings have been reshaping life on Earth for tens of thousands of years, long before factories or fossil fuels, and the most important changes are often indirect, systemic, and easy to overlook if we focus only on counting extinct species.

The deep history of human impact

Harper, a historian who began his career studying ancient Rome, argues that understanding humanity’s effect on the biosphere requires a much longer timeline than the Industrial Revolution. The first great transformation came when hunter-gatherers, armed with social cooperation, tools, and fire, spread out of Africa and encountered ecosystems dominated by enormous mammals. These megafauna—mammoths, mastodons, giant bison, and their predators—had ruled for millions of years. They reproduced slowly and had never faced a predator capable of killing healthy adults. Humans, as social, tool-making predators who could hunt cooperatively and use fire to drive animals into traps, were something entirely new. Around 20,000 years ago, they formed an even stranger pa