Did you eat a hot meal today? It's a smart thing to do, as our ancestors learned.

According to a new study, a surge in human brain size that 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.

Read more at National Geographic.