A study published yesterday in the journal PNAS puts weight behind the hypothesis that--more than any social or environmental factor--humans own their giant cognitive leap to the ancestral chefs and proto grill masters who invented cooked food.
Why? According to the researchers, a diet of raw foods can's support an endless growth of both brawn and brains. Larger body sizes and bigger brains both meant more energy use, which meant more time spent eating each day.
And, since no primate can sustain a daily foraging requirement of much more than eight hours (gorillas average close to eight, but sometimes spend closer to nine), our ancestors must have found some way to get more energy in less time.