Sugar power: the full story of brain development in humans

A new study published in Science has challenged the long-held belief that meat was the primary driver of human brain expansion. The research, led by Jennie Brand-Miller and Karen Hardy, suggests that a combination of sugar and meat fueled the development of the human brain.

While meat provided essential amino acids and micronutrients, the study posits that natural sugars and starch found in fruits and honey supplied the glucose required to power the rapidly-growing human brain. The authors note that the human brain is disproportionately large compared to body size and demands substantial energy, which is primarily obtained through glucose metabolism.

The study models the glucose needs of humans and their ancestors, revealing that sugars provided over 25% of dietary energy over a period of four million years. This glucose requirement increased as the brain grew, from around 300 grams in early hominins to about 1,500 grams in modern humans.

The researchers emphasize that the evolution of the human brain is a story of both carbohydrate and animal foods. While animal foods were undoubtedly important, the brain's need for glucose has been largely overlooked in past anthropological theories. The modelling suggests that early humans relied on naturally-sweet foods, such as fruit, long before cooked grains became a regular part of the diet.

The findings challenge the traditional view that meat was the sole source of energy for brain development. Instead, the study highlights the crucial role of carbohydrates, particularly natural sugars, in powering the evolution of the human brain.