I was reading the comments regarding eating cold food and this article was brough to mind.  Thought you might find it interesting.

http://www.popsci.com/science/article/2012-10/eating-cooked-food-made-us-human-study-finds

" A new paper examines the metabolic restrictions of a raw diet, and suggests that our primate cousins are limited by their inability to heat their dinners."

"the largest primates do not have the largest brains, a perplexing question. Encephalization (a larger brain size per body size than you'd expect) has long been thought to be a key feature setting humans apart from other primates, and mammals as a whole,"

" If we ate an only-raw diet, to maintain the body size we humans possess, as well as the number of neurons our brains possess, people would have to eat for more than 9 hours per day, they found."