 We have upper teeth because we eat nutrient-dense foods. That's the reason God gave us canines, teeth. And dogs have canine teeth. All predators have canine teeth. We chew dense food. So God made our stomachs simple stomachs so we can eat a variety of foods. A little bit of meat, a little bit of salad, a little bit of nuts, a little bit of everything. We're scavengers. That's how humans survived all these years. But we really survived and matured quickly when we started eating meat.