Brain size in apes and humans differ. This article uses ass-backwards reasoning to explain our brain. We learned to cook, and therefore the extra calories made it grow!!! But it was Homo erectus that cooked after lots of brain enlargement, prior to cooking. The brain of our ancestors took off on its own, for no rhyme or reason.:-http://blogs.discovermagazine.com/notrocketscience/2012/10/23/apes-brains-energy-body-size/#more-7842-The article also notes that we are really nothing but apes.