Perhaps nothing sets humans apart more from other species than our brains. Comparatively large and wonderfully complex, they’re what allow us to communicate across mediums – from the written and spoken word to expressive arts like dance and sculpture – and to ponder our own existence.
But all this ability comes at a price: Our brains are metabolically expensive – meaning they account for roughly 20% of daily energy expenditure, compared to about 8% in modern primates. When looking at our evolutionary past, it’s clear that as the quality and diversity of our ancestors' diets improved, their brains were able to increase in size. This increase in brain size corresponded to a smaller gastrointestinal system, since their diets meant they needed to do less digestive “work” to obtain nutrients. The extra energy that was available from a shrinking gut could be channeled to the brain, helping promote its growth and development. A high-quality, nutrient dense diet – in conjunction with other aspects of daily living, such as exercise – has had a crucial role in shaping cognitive capacity and brain evolution.