If, as here proposed, homology results from organizing processes that integrate and fixate generic and conditionally generated building elements into a stable body plan, then neither genetic nor developmentally based definitions alone can capture the essence of this phenomenon. A more encompassing concept that represents the integration between different levels of organization is needed, one I propose to call the “organizational homology concept.” This concept is based on seven prernises (four established by earlier authors, and three proposed in tbe current chapter):
1. Homologues are constant elements of organismal construction; they are independent of changes in form and function (Owen, 1843);
2. Homology signifies identity, not similarity (Owen, 1843);
3. Homologues are fixated by hierarchically interconnected interdepeodencies (“burden”; Riedl, 1978);
4. Homologues are developmentally individualized building units (Wagner, 1989a,b);
5. Homology denotes constancy of constructional organization despite changes in underlying generative mechanisms;
6. Homologues act as organizers of the phenotype; and
7. Homologues act as organizers of the evolving molecular and genetic circuitry.