How did humans evolve larger and more sophisticated brains? Evolution, in general, depends on a special combination of circumstances: part genetics, part time, and part environment. In the case of human brain evolution, the main environmental influence was adaptation to a 'shore-based' diet, which provided the world's richest source of nutrition, as well as a sedentary lifestyle that promoted fat deposition. Such a diet included shellfish, fish, marsh plants, frogs, bird's eggs, etc. Humans, and more importantly, hominid babies started to get fat, a crucial distinction that led to the...