Abstract
Food allergy is pathophysiologic ally based on stimulation of the immune system at the first exposure, and allergic reactions develop during following exposures. Therefore, memory is the cornerstone of an allergy, as seen in the adaptive immune system. The adaptive immune system was first introduced during evolution in vertebrates, so we can say that invertebrates do not have allergic reactions. We can conclude that food allergy is a complication of animal evolution. Evolution also can cause diseases and complications; therefore, understanding it may help in allergy treatment.