Photos document the health of people living off traditional diets. Even the aged appear to have perfect teeth and good health. This is true for native Celts, Inuits, Aborigines, Native American, and other. All of those eating traditional diet have exceptional health.
There is also documentation of first and second generation introduced to western diet. Tooth decay are common, bone abnormalities occur regularly, and general health falls into chaos!
It is difficult to picture ourselves eating as our ancestor did, but traditional diet is what our bodies are adapted for. The Scottish fishermen are likely most similar to my ancestry; they ate primarily fish and oats. I am rethinking my own diet.
I highly recommend reading this book. With great willpower it is possible to change diets to fit our bodies needs.