An archaeological dig of a cave in South Africa provides evidence of "burning events" 600,000 years older than other conclusive sites.

Reuters

In 2009 Harvard anthropologist Richard Wrangham offered a novel theory on the evolution of humans: Homo erectus could not have evolved nearly two million years ago without consuming cooked food. No way, he argued, could raw food have provided the calories necessary for the development of the human brain. Its digestion alone requires too much energy. But cooked food changed everything. It's much easier to digest, freeing up energy to fuel our brains, not our guts. "The extra energy gave the first cooks biological advantages," he wrote. "They survived and reproduced better than before. Their genes spread. Their bodies responded by biologically adapting to cooked food, shaped by natural selection to take maximum advantage of the new diet. There were changes in anatomy, physiology, ecology, life history, psychology and society."

But there was one small problem with Wrangham's theory: Cooking food requires fire, and the oldest unequivocal evidence for human control of fire only ("only") dates to 400,000 years ago. No fire, no cooking. The few archaeological sites in Africa, Asia, and Europe with trace fire evidence dating back to 700,000 to 1.5 million years ago are open air, meaning wildfires cannot be ruled out, or are inconclusive for other reasons.