Some scientists have proposed designating a new geological epoch, the Anthropocene, that would cover the period since humans became the predominant environmental force on the planet. But when would you have it begin? Some geologists argue that the Anthropocene began with the Industrial Revolution, when fossil fuel consumption started influencing climate. Others point back several thousand years earlier to the onset of agriculture, when humans cleared swaths of forest to make way for neat little rows of cultivated crops.
But the roots of the Anthropocene may stretch even farther, deep into the Stone Age: Humans have been driving other species to extinction since before we were even human, back at least 2 million years to the early days of the genus Homo.
The human family grew up in East Africa during an age of carnivores. Species like Australopithecus afarensis foraged for fruits, nuts and seeds amid large (and probably scary) meat-eating mammals such as saber-toothed cats, giant hyenas and otters as big as bears.
Those creatures had their peak about 3.5 million years ago. About a million years after that, hominids invented stone tools. Early species of Homo started to scavenge and eventually hunt other animals, muscling in on the carnivores’ culinary turf. Our ancestors became so good at killing or stealing prey that some meat eaters couldn’t compete, and they died out. Since hitting their peak, the large carnivores of East Africa have lost 99 percent of their diversity.