Learning to cook food helped humans evolve faster than other primates, a new theory has suggested.
Research has found cooking helped our guts grow smaller, while our brains grew bigger. The 25% of energy saved by eating cooked food is believed to have been transferred to the brain.
Without cooking, an average person would have to eat around five kilograms (11lbs) of raw food a day to obtain enough calories to survive.
Horizon: Did Cooking Make Us Human? will be shown on Tuesday, 2 March 2010, at 2100 GMT on BBC Two. It will be available for seven days after that on the BBC iPlayer
Did the discovery of cooking make us human?