Figure 4.

Proposed framework for allergic disease based on tinbergen’s four questions (156). In the context of evolutionary history, the ancestral allergic responses are postulated to be a form of antiparasitic immunity that persisted across vertebrates. In terms of development, the emergence of global de-worming efforts and improved sanitation practices resulted in changes in the persistence and primary function of the trait, masking its original function against helminthic parasites. This resulted in a mechanism involving misdirected responses against innocuous allergens. However, the trait persisted due to its conferred survival value for immune homeostasis.