 Defusing the conceptual tensions between developmental and evolutionary biology with respect to homology of function has a direct impact on the causal generalizations and inferences made from model organisms  (Section 4).  Activity-function homology directs our attention to the stability or conservation of activities. This conservation is indicative of when the study of mechanisms in model organisms will produce robust and stable generalizations  (Section 1.3).  The widespread use of functional homology in developmental biology is aimed at exactly this kind of question, which explains its persistence in experimental biology despite conceptual ambiguities. Generalizations concerning molecular signaling cascades are underwritten by the coordinated biochemical activities in view, not the developmental roles (though sometimes they may coincide). Thus, activity-function details about a signaling cascade gleaned from a model organism can be generalized via homology to other unstudied organisms even if the developmental role varies for the activity-function in other species.