i think the need to cook our food stems from the fact that we have been cooking it for so long we lost the ability to safely digest it raw in some cases , most omnivoes like chimps, dont eat a great deal of meats, evolutionaraly speaking however our digestive system has gotten smaller than that of our more herbivoreistic cousins and allowed for larger brain development becuase we took meat and especially becuase we took cooked meat into our diets, (any cooked food takes less work to break down and in some cases provides more nutrients animal fat is very high in these things), science has found a direct correlation-relationship between this, larger brains take up lots of energy and are the primary competer with the digestive track for the bodies energy, muscular structure aside, a smaller more efficent digestive system is not possible without cooked food especially high energy content cooked foods such as meat