Omologia e analogia : Un problema fondamentale per la comprensione della vita

In the primary view of the world the ultimate cause for the relatedness of forms of life (plants, animals, and human beings) was attributed to an act of creation on the part of unknown higher powers. In the Occident this view found its strongest expression in the belief in one single power of creation compelled to realise all that can potentially be created. This led to the notion of a «chain of being», ranging from inanimate mineral matter to plants and animals; it includes the human race as well as superhuman beings and even extends to the highest beings close to the Creator. Thinking in terms of sensible analogies dominated all thinking about the multitude of forms. The question about the Cause was answered with belief in a creative power. The Copernican revolution slowly gave rise to a new conception of creation: the Creator became the prime mover, but as a result He also acquired distance. He was replaced by «Nature», endowed with creative powers. Relations between forms were attributed to Nature on the assumption that they were due to the effects of spiritual factors rather than the material context for evolution. This led to the development of an idealistic morphology, which ever since Goethe implied the existence of a principle of inner relationship (homology) more important than any functional similarity (analogy). The results were laid down in the «natural System». This was even the intellectual context for Lamarck's first theory of evolution, which was, however, not recognized, owing to the fact that he still assumed non-material creative factors to be of decisive importance. Darwin blended the newly developing notions about the material evolution of organisms from the simplest to the highest form into a theory, which met the intellectual requirements of the time. His approach tended to play down the ultimate causes and increasingly assumed them to be inherent in matter (as sources of variation) and to be affected by outer factors (such as natural selection). By means of experimental methods modern biology attempts to find evidence for the causes underlying descendancy in embryonic and more recently in cellular life; for instance, through analysis of the genetic factors in heredity experiments, as well as in the macromolecular structure of chromosomes in the cell nucleus and the heredity substance in the cytoplasm. Attempts to prove that the form relatedness perceived in the visible world (mediocosmos) also extends into the microcosmic world of hereditary predisposition have so far not been successful. Although for the time being this study has only provided evidence for a clear-cut separation of existing morphology from the processes taking place at the macromolecular level, it has contributed to an expansion of the original principle of homology. Even with the prevalence of a general concept of descent, i.e., a theory of evolution, the central problem of morphology remains as yet unanswered.