I went to a talk on nutrition recently which led me to do some research. Of particular interest to me is just what early humans ate, but I've also found a lot of uncertainty around what led to the evolution of the human brain. There seem to be a variety of arguments, from the claim that meat fuelled brain development (common thinking just a few years ago), to starches helped fuel brain development (paper last year by Dr Karen Hardy) to cooking anything at all did it. Not knowing that much about biology I got to wondering about all this conflicting information. I would have assumed that just eating a particular diet wouldn't trip brain development, surely there need to be selective pressures in the environment that favoured the changes that lead to big brains? Sure the high energy demand would require certain food sources, but that seems more likely to me to be a behavioral change as early man found the diets that worked best. I read that cooking is considered one of the most likely contributors to obtaining more energy from existing diets and there are arguments for fire use as long ago as 1.5 million years. I assume our earlier ancestors were largely frugivores like other members of Hominidae, but that changes in brain anatomy and the consequent demand for high energy foods might have led to various dietary strategies with no one specific diet being dominant. The result would be a variety of strategies and adaptive changes, which seems to be what we see. The other thing that I rarely see mentioned in relation to "paleo" diets is what nature is doing. In natural settings, I wonder if it is important for people to live past effective reproductive ages. Thus if a diet is good for people in that it meets high energy demands while one is reproductive, but causes all sorts of chronic disease later, nature couldn't care less (eg I've read that Inuit do alright on a mostly meat diet, but have shorter lifespans on average). That's still a good evolutionary strategy. Today though we might prefer a diet that facilitates living to old age in good health. Can anyone offer any thoughts about the current state of evolutionary biology in the context of both brain evolution and diet?