We were a hunter/gatherer society for a reason. Meat/fat is incredibly nutrient and calorically rich, which gave us the ability to grow our brains out and shrink our stomachs. Once we discovered agriculture, we found we could more safely and sufficiently meet our caloric needs with breads, and meat became a luxury as livestock is expensive and hunting was inefficient and costly in a time that normalized daily labor in the community. Once we industrialized farming, we could once again fulfill our demands for meat.