The potato is being credited with fuelling the extraordinary expansion of the brain in human evolution.
The move towards eating meat was previously suggested as the main cause of the increase but a new study suggests it was driven by carbohydrate consumption, particularly in the form of starch.
It says starches would have been readily available to ancestral populations in the form of potatoes as well as seeds and some fruits and nuts.
Discovering how to control fire meant potatoes could be cooked, while the evolution of extra saliva proteins known as amylase genes meant humans could break down the calorie-rich starches into sugars that fed the brain.
Lead researcher Dr Karen Hardy, of the Autonomous University of Barcelona, said the brain uses up to 60 per cent of our blood glucose and this demand is unlikely to have been met on a low-carb diet.
