Sugar power: the full story of brain development in humans

A recent study published in Science suggests that both sugar and meat played a crucial role in human brain expansion, challenging the notion that meat alone fueled our larger brains. Led by Jennie Brand-Miller, a professor of human nutrition at the University of Sydney, the multi-centre research posits that natural sugars and starches found in fruits and honey provided the essential glucose required to power a rapidly-expanding human brain.

The authors explain that while meat has traditionally been considered a key component in human brain development, offering critical amino acids and micronutrients, increasingly available evidence highlights the indispensable role of glucose derived from plant sources. Over a period of four million years, the human brain grew from around 300 grams in early hominins to about 1,500 grams in modern humans, requiring substantial amounts of energy.

According to the study, sugars supplied over 25% of dietary energy, fulfilling the obligatory glucose demand. The researchers employ modeling techniques to demonstrate that natural sugars and starches, not merely meat, were the primary energy sources for our metabolically expensive brains. The study does not discount the importance of animal foods, such as meat, but emphasizes that glucose from plants was equally vital for human brain development.

Prof. Hardy, an archaeologist from the University of Glasgow, explains that raw starch does not release glucose, suggesting that early humans relied on naturally-sweet foods long before cooked grains became a regular part of their diet. The findings challenge the traditional dietary focus on animal foods, proposing that carbohydrates played a significant role in the evolution of our larger brains alongside animal foods.