When did humans start cooking food?

Cooking is important — in fact, some researchers believe it's what allowed our human ancestors to unlock the extra calories needed to grow larger brains. So when was cooking invented?

The timing is uncertain, but evidence suggests people were cooking food at least 50,000 years ago and as early as 2 million years ago. This evidence comes from two fields: Archaeology and biology.

One piece of archaeological evidence for cooking is cooked starch grains found in dental calculus, or hardened dental plaque. "People can find it in teeth that are 50,000 years old," said Richard Wrangham, a retired professor of biological anthropology at Harvard University and the author of "Catching Fire: How Cooking Made Us Human" (Basic Books, 2009).

But earlier than that, the evidence is less clear. Generally, scientists look for evidence that people were controlling fire. But evidence of controlled fire isn't necessarily evidence of cooking; — people could have used that fire for heat or to make tools, for example.

"There's evidence of fire all the way through the archaeological record," said Bethan Linscott, an archaeological geochemist at the University of Oxford. "But the problem is distinguishing whether it was controlled fire or fire that was scavenged — you have a wildfire moving through the landscape and you have hominins who are able to pick up a smoldering twig and take advantage of that in order to maybe process tools or cook."

Related: When did humans discover how to use fire?

"One of the key things when you're looking for evidence of fire control is an actual combustion structure — so maybe having stones arranged in a circle and then some ash in the middle, maybe some phytoliths [silica structures left by long-dead plants] and burnt artifacts and things," Linscott said.