Carbohydrates played key role in human brain evolution, study finds

A recent scientific study by researchers from the University of Sydney and the University of Glasgow has highlighted the significant role carbohydrates may have played in the evolution and expansion of the human brain over millions of years. The study suggests that natural sugars and starchy foods provided a vital energy source for this development.

Published in Science magazine, the research notes that the average brain size of human ancestors increased nearly fivefold over about four million years, from around 300 grams in Australopithecus afarensis to approximately 1.5 kilograms in modern Homo sapiens.

The researchers pointed out that such a dramatic increase in brain size required a steady supply of energy, with glucose being a primary source. This offers an additional explanation for the emergence of advanced cognitive abilities, complementing traditional theories that have focused on the role of meat and animal-based foods.

Multiple lines of evidence and diverse food sources

The research team examined fossilized teeth, analyzed ancient isotopes, studied changes related to recognizing ripe fruits, and reviewed genetic evidence concerning sweet taste perception and carbohydrate metabolism.

Their estimates indicate that an adult human may require between 150 and 250 grams of glucose daily to meet the needs of the brain and certain organs and tissues, while young children need about 125 grams.

The study also notes that fruits and honey were likely primary carbohydrate sources in the early stages of human evolution, with cooked starchy foods such as roots and tubers becoming more important as humans learned to use fire and cook.

The findings provide a broader perspective on the history of human brain evolution, with researchers concluding that access to carbohydrate-rich, energy-dense foods was among the factors supporting this development, alongside other dietary and environmental changes.