Philosophical Perspectives on Neuroendocrine–Immune Interactions: The Building Block Model and Complementary Neuro-Endocrine-Immune-Microbiota Systems Approaches

The study of the interactions between the neuroendocrine and immune systems is a highly interdisciplinary research endeavor, in which the boundaries between the systems being studied become blurred. We address a common scientific perspective in dealing with intertwined complex systems, namely the conceptual approach in science that treats each system (e.g., nervous, immune, endocrine systems) as separate units or “building blocks” with unique functions that correspond to specific structures. While there are merits to this way of decomposing complex systems, there are several reasons why such an approach is limited when trying to recompose a physiological system that is engaged in intricate co-functioning and that is the result of co-development, and co-evolution, not just between these systems, but with the gut microbiota as well. Our suggestion is to take an alternative ecological evolutionary developmental approach to the neuro-endocrine-immune-microbiota system (NEIMS) as a whole, which can serve as complementary to the predominant building block perspective.