Compared with other population groups, the way of life of farmers can be viewed as being similar to that of our ancestors. The settled continuation of generations within certain critical geographical and environmental conditions requires a special local network of knowledge and experience.

The immune system provides protection against microbes and their toxins. Each strong reaction impedes an active adaptation. Allergy is therefore a harmful intolerance and represents one of many different paradoxes.

The aim of this chapter is to demonstrate some of the interactions of tolerance and adaptation from a historical background. © 2014 S. Karger AG, Basel.