Heavy metal toxicity and the ALMs your should be scared of.
Millions of years ago, man had only little influence on the environment, the could only till the land to get what he eats, these foods he processed in a way which could be described as crude when compared to our contemporary food processing method and these foods were taken in a form which was as natural as possible. Little attempts were made towards complete processing of these foods while some of them were eaten raw. A food processing industry. Source: Wikimedia - CC BY-SA 3.0.