Nine human species walked the Earth 300,000 years ago. Now there is just one. The Neanderthals, Homo neanderthalensis, were stocky hunters adapted to Europe’s cold steppes. The related Denisovans inhabited Asia, while the more primitive Homo erectus lived in Indonesia, and Homo rhodesiensis in central Africa.
Several short, small-brained species survived alongside them: Homo naledi in South Africa, Homo luzonensis in the Philippines, Homo floresiensis (“hobbits”) in Indonesia, and the mysterious Red Deer Cave People in China. Given how quickly we’re discovering new species, more are likely waiting to be found.
By 10,000 years ago, they were all gone. The disappearance of these other species resembles a mass extinction. But there’s no obvious environmental catastrophe – volcanic eruptions, climate change, asteroid impact – driving it. Instead, the extinctions’ timing suggests they were caused by the spread of a new species, evolving 260,000-350,000 years ago in Southern Africa: Homo sapiens.
The spread of modern humans out of Africa has caused a sixth mass extinction, a greater than 40,000-year event extending from the disappearance of Ice Age mammals to the destruction of rainforests by civilisation today. But were other humans the first casualties?
We are a uniquely dangerous species. We hunted wooly mammoths, ground sloths and moas to extinction. We destroyed plains and forests for farming, modifying over half the planet’s land area. We altered the planet’s climate. But we are most dangerous to other human populations, because we compete for resources and land.
History is full of examples of people warring, displacing and wiping out other groups over territory, from Rome’s destruction of Carthage, to the American conquest of the West and the British colonisation of Australia. There have also been recent genocides and ethnic cleansing in Bosnia, Rwanda, Iraq, Darfur and Myanmar. Like language or tool use, a capacity for and tendency to engage in genocide is arguably an intrinsic, instinctive part of human nature. There’s little reason to think that early Homo sapiens were less territorial, less violent, less intolerant – less human.