Proponents argue that unlike protein and fat, carbohydrates are not an essential macronutrient.  It is said that our bodies can still run just as efficiently with small amount or even with none.  Moreover, carbohydrates have been identified as one of the major culprits for obesity.  However, a study headed by Karen Hardy linked carbohydrates to the successful evolution of the human brains over the last million years.

Although the group acknowledged that the alarming rise of obesityand metabolic incidents ignited the public to start on healthier diets, it is not clearly defined and agreed upon by experts what a healthy diet should be comprised of.  Karen and her colleagues from Catalan Institution for Research and Advanced Studies in Spain analyzed archaeological, anthropological, physiological, anatomical and genetic data to prove that carbohydrates were no less important than animal protein in the development of big brains, making humans smarter. 

In their paper entitled, "The Importance of Dietary Carbohydrate in Human Evolution", the researchers argued that starch-rich foods were essential for satisfying the increased energy needs of the growing human brain during the Pleistocene period and later.  Evidence from archaeological sites around the world shows that tubers, seeds and nuts were often found in abundance in areas occupied by early hominins, which would have made them a readily available source of nutrition. 

In their research, they have come up with multiple observations that can help better understand the function of carbohydrates.  For one, the amount of energy required by the brain alone is 25 percent of the body's energy and 60 percent glucose supplies in the blood.  A modern human needs a reliable source of glycemic carbohydrates - these are carbohydrates that can be metabolised into glucose- to support the function of not just the brain but also of kidneys, red blood cells, and the tissues of the reproductive organs.  With high demands for glucose, the researchers believe that a low-carb diet would not have sufficed this.  The same goes during human pregnancy and lactation where a low-blood glucose could pose danger to mother and child.  The increase in the production of salivary amylase, an enzyme that is essential for the breaking down of carbohydrates into sugar, are also thought to be around the time the brain began to increase in size.  This was also aided by the development of cooking which made raw starches easier to digest.

"Although previous studies have highlighted a stone tool-mediated shift from primarily plant-based to primarily meat-based diets as critical in the development of the brain and other human traits, we argue that digestible carbohydrates were also necessary to accommodate the increased metabolic demands of a growing brain," researchers write.