With the global increase in obesity and diet-related diseases, such as type 2 diabetes and heart disease, there is renewed interest in Palaeolithic diets with a meat-centered approach to eating. It is believed by many that meat eating kick-started human brains to develop into larger and more complex organs which gave humans the edge on intelligence.
A new study done by Dr. Karen Hardy challenges this assumption by suggesting that there were multiple factors that helped us evolve bigger brains, most notably cooking starchy foods to provide glucose and the evolution of salivary amylase to allow humans to use starch as a source of needed energy.
The human brain uses 25% of the calories a person consumes and gobbles up to close to 60% of all the glucose circulating in the blood. Hardy believes that the high glucose demands of the brain could not be met on a low carb diet. Starches were always available to our human ancestors but it was not until cooking evolved in the Pleistocene era that food starches became easier and less time consuming to chew and more palatable. Cooking food starch releases more calories as glucose than is available in the raw form. With more glucose available from food, glands in the human mouth began to produce more salivary amylase which allowed humans to absorb and use glucose which is needed for brain function. Put all these coevolving adaptations together, along with ample meat in the diet of early man, and human brains grew bigger.
