According to a new study it was revealed that carbohydrate consumption, particularly in the form of starch was critical for the accelerated expansion of the human brain over the last million years.
The study suggests that eating meat may have kick-started the evolution of bigger brains, but cooked starchy foods together with more salivary amylase genes made us smarter still.
Starches are readily available in the form of tubers, as well as in seeds and some fruits and nuts and while raw starches are often only poorly digested in humans, when cooked they lose their crystalline structure and become far more easily digested.
Researchers propose that after cooking became widespread, the co-evolution of cooking and higher copy number of the salivary amylase (and possibly pancreatic amylase) genes increased the availability of pre-formed dietary glucose to the brain and foetus, which in turn, permitted the acceleration in brain size increase which occurred from around 800,000 years ago onwards.
The study was published in The Quarterly Review of Biology.