Their findings offer a different perspective on the longstanding scientific view that meat consumption was a key driver of human evolution. The human brain, though just 2% of an adult’s body weight, consumes about a fifth of the body’s resting energy, and as much as two-thirds in a young child. “The human brain is unusually large for our body size and requires substantial amounts of energy,” said University of Sydney’s Professor Jennie Brand-Miller, lead author of the study. In the study, the authors calculated how much glucose the brain, red blood cells, kidneys and reproductive tissues would have required at different stages of human evolution. “Our study suggests sugars and starches may have helped shape the development of the human brain and many of the traits that make us human.”