Obesity: An Evolutionary Perspective

© The British Academy 2012. All rights reserved. The brain consumes about 20 per cent of the total energy intake in human adults. Primates, and especially humans, have unusually large brains for body size compared with other vertebrates, and fuelling these is a significant drain on both time and energy. Larger-brained primates generally eat fruit-intense diets, but human brains are so large that a reduction in gut size is needed to free up sufficient resources to allow a larger brain to be evolved, placing further pressure on foraging. The early invention of cooking increased nutrient absorption by around 30 per cent over raw food. Increasing digestibility in this way perhaps inevitably leads to risk of obesity when food is superabundant, as it is in post-industrial societies. However, obesity has clearly been around for a long time, as suggested by the late Palaeolithic Venus figures of Europe, so it is not a novel problem.