From Scientific American, a piece on the “Cooking Hypothesis” (which yours truly helped develop some years back).
Our hominid ancestors could never have eaten enough raw food to support our large, calorie-hungry brains, Richard Wrangham claims. The secret to our evolution, he says, is cooking
Cooking does indeed turn a lot of stuff that is not edible to humans (or any primate) into usable energy. We think the increase in body size that comes along with the genus Homo (with Homo erectus and kin) is itself a biological signal of cooking.
The problem with his idea: proof is slim that any human could control fire that far back. Other researchers believe cooking did not occur until perhaps only 500,000 years ago. Consistent signs of cooking came even later, when Neandertals were coping with an ice age. “They developed earth oven cookery,” says C. Loring Brace, an anthropologist at the University of Michigan at Ann Arbor. “And that only goes back a couple hundred thousand years.” He and others postulate that the introduction of energy-rich, softer animal products, not cooking, was what led to H. erectus’s bigger brain and smaller teeth.
Yes, indeed, people do argue about the evidence for early fire. I am convinced that there is sufficient evidence in the early Paleolithic of fire to assume that these later dates proposed by Brace and others are wrong, and that controlled use of fire may well date to nearly 2.0 million years ago.
If you want to read the first peer reviewed paper outlining this idea, you can get it here.