In the mainstream scientific community there is a consensus that there was a major dietary shift that occurred in our evolution which allowed us, as humans, to have the large energy-hungry brains we have now. The most largely accepted theory is that it was hunting down large predators on the savanna. The Wrangham hypothesis that it was cooked tubers is getting press lately because he has a book out. But there is another theory that I think deserves a look: that our move from chimpanzee-like primate to humans was when we started living by the waterside. That would account for why the human brain seems to run on omega-3 fatty acids that are so abundant in seafood.
Anecdotal, but the diet I have settled on is most like what early humans dwelling by the waterside might have eaten. I personally gravitate towards water: I'm a good swimmer and when I think about processing a rabbit or digging in the ground for tubers vs. grabbing a fish and a coconut....well I think most early humans would have picked the latter. Note that I'm not advocating the discredited aquatic ape theory, which theorized an ape ancestor that had gills and fins.
While we fully agree that the structural, cognitive and visual development of the brain requires adequate amounts of certain nutrients including DHA (Crawford and Sinclair 1972), we think the initial shift might have included more abundant and easily obtainable DHA-rich sources such as shellfish, crayfish, fish, turtles, birds and eggs (Broadhurst et al. 1998). Since the primary source of DHA is algae and plankton, it is abundant in the marine and lacustrine food chains, but almost absent in the meat, fats and offal associated with carnivore remains (Broadhurst et al. 2002). Other brain-selective nutrients are also more abundant in aquatic than in terrestrial milieus. This is notably the case for brain-selective minerals such as iron, copper, zinc,selenium, and iodine (Table 5). Of all the major food groups, shellfish requires the least amount (900 grams) to meet the minimum requirement for all five minerals, and is also the food group for which these requirements are most evenly distributed. Eggs (2500 grams) and fish (3500 grams), both more abundant at the waterside than in terrestrial environments, are next, while 5000 grams of meat, five times more than shellfish, would be needed to meet the minimum daily requirements for all five minerals (Table 5). Iodine especially is more abundant in littoral food chains than terrestrial food chains, and before the iodinisation of drinking-water and salt, hypothyroidy caused by iodine deficiency resulted in mental retardation and cretinism in millions of humans who lived away from the coasts....
Humans have about ten times as much subcutaneous fat as most terrestrial mammals and non-human primates including chimpanzees, and in this respect they approach ‘lean’ aquatics such as fin whales