Cooking food causes it to break down in ways similar to digestion. Thus, animals that eat cooked food don't have to expend as much energy digesting it as do those that eat their meals raw. Because of this, the researchers in this new study proposed that learning to cook food allowed early humans more time to engage in other pursuits that eventually led to the development of larger brains. To prove their idea sound, they compared the amount and types of food various primates consume and compared it with the amount of energy necessary to fuel their brains which they calculated by counting neural cells.
(Medical Xpress)—Brazilian researchers Karina Fonseca-Azevedo and Suzana Herculano-Houzel suggest humans evolved bigger brains because they learned to cook their food. In a paper published in the Proceedings of the National Academy of Sciences, the two outline research they've conducted that involved counting the number of neurons in the brains of various primates, the results of which showed that the only way early humans could have evolved bigger brains was to find a way to get more energy from the food they ate, i.e. cooking it.