Introductory Remarks of the Editor-in-Chief

A multitude of reasons exist to study phylogeny. Man is part of the biological entity of all life on earth. Besides, hemoglobins insulin structures of different vertebrates contribute substantially to the clarification of evolutionary steps on a molecular basis. The animal kingdom is divided into two major groups. Most of the invertebrates (worms, arthropodes and molluscs) belong to the protostomia, while deuterostomia contain ectinoderms, prochordates and all the vertebrates. It is a fascinating revelation to find homologies on a molecular basis between the two groups. As early as 1966 my own group was able to demonstrate insulin-like activity in Helix pomatia, in the footpad and in the hepatopancreas. One of the most successful laboratories, headed by Sture Falkmer, published the insulin structure of the hag fish, later on the decisive question was, whether or not unicellular organism produce insulin too. Over the past ten years several groups working in the field of Comparative Endocrinology claimed that classical peptide hormones, especially of the insulin family, must have been present in earlier, presumably less complicated forms. Peptide hormone-producing cells have a common origin in the neural ectoderm. However, in this area several principal difficulties arise: