According to a new study, a surge in human brain size tehat occurred roughly 1.8 million years ago can be directly linked to the innovation of cooking.

Homo erectus, considered the first modern human species, learned to cook and doubled its brain size over the course of 600,000 years. Similar size primates—gorillas, chimpanzees, and other great apes, all of which subsisted on a diet of raw foods—did not.

"Much more than harnessing fire, what truly allowed us to become human was using fire for cooking," said study co-author Suzana Herculano-Houzel, a neuroscientist at the Institute of Biomedical Sciences at the Federal University of Rio de Janeiro in Brazil.


A Diet Unfit for King Kong

Herculano-Houzel and colleague Karina Fonseca-Azevedo measured the body and brain masses of primates and compared them with their caloric intake and hours spent eating. Unsurprisingly, the results showed a direct correlation between calories and body mass. In other words, the bigger you are, the more you have to eat.