The teeth thing is just because of our high sugar, high grain diet

The first* people with bad dental health were Egyptians as they lived on bread (which packs your teeth and feeds the bacteria that ferment it and make acid) before that, and until the invention spread, people died of old age with all their teeth intact

I eat very low carb - almost entirely meat due to allergies, and haven't had a cavity since I started doing that, despite me nearly never brushing or flossing my teeth

*There were also people who lived in the tropics and ate a lot of fruit, and those with sugar cane.