An Ecological Theory of Animal Progress: A Revival of the Philosophical Role of Zoology

AN ECOLOGICAL THEORY OF ANIMAL PROGRESS: A REVIVAL OF THE PHILOSOPHICAL ROLE OF ZOOLOGY F. D. POR* Motto: If the biosphere « that system which maximizes orderfor the terrestrial surface, it becomes a necessary state of the system rather than an accidental one.—H. J. Morowitz [1, p. 146] Zoology in our day is in a state of prolonged crisis. The enthusiasm of the Darwinian days has long since faded. Not that "classical zoology" has accomplished its tasks. Unlike geography, zoology still has to work for many decades on the "mapping" of our animal world. New species of animals are described at the same laborious rate as before, even new phyla and classes are still being discovered. But one more and more frequently hears the question, What for? Zoologists of our generation are in a position of embarrassed defense. The roots of the malaise of zoology reside in the lack of a zoological philosophy. In the days of Darwinian enthusiasm, the deciphering of major evolutionary steps in the animal world—like the story of early chordates, the history of the horse, even the documentation of the animal origins of man—served as major arguments for the evolutionary theory. Then, the planula, the trochophora, the amphioxus, the Archaeopteryx were main trumps in the clash of ideas. But once the theory of natural selection became established it also became evident that it applies to all the kingdoms of the living world. However, if there is an animal kingdom separate from the microorganisms , the fungi, and the plants, there also has to be a special theory of the animal kingdom, subsumed under or additional to the general theory of natural selection. Even at first glance it is obvious that the animal world stands out against the rest of life by virtue of its increasing complexity, individuality , and functional homeostasy. But modern neo-Darwinist theory, having made important contributions to the explanation of the process ?Department of Zoology, Hebrew University of Jerusalem, Jerusalem, Israel.© 1980 by the University of Chicago. 0031-5982/80/2303-0137$01.00 Perspectives inBiology and Medicine ¦ Spring 1980 \ 389 of speciation, staunchly upholds the dogma of the democratic equality of all species. In zoology, the very idea of "lower" and "higher" animals exhales a sulphurous smell of heresy. Since all the species which are alive today have, each in its own way, tackled the problems of survival and have not yet fallen prey to natural selection, it follows that all species from amoeba to man are basically equal (see, e.g., Maynard-Smith [2]). If this is so, then the countless animal species are scattered around like the multitude of the heavenly bodies, some of them clumped together in clusters, in galaxies ofbigger and smaller phyla, but basically exhibiting a formless chaos. In contrast to this feeling of an endless and shapeless zoological cosmos ofmillions ofspecies, the last 3 decades yielded a tremendous philosophical breakthrough: the demonstration of the basic unity of all life at the energetical, biochemical, and genetical levels. What is today almost vernacularly called "molecular biology" has attracted and satisfied the brightest and most enthusiastic minds of our generation of biologists. The feeling, best expressed by Monod in his Chance and Necessity, is that the biological world has been fathomed and understood and that there are no basic differences wherever we turn in search for oddities. If so, then zoologists are perhaps really nothing more than some sort of philatelists, as they frequently have been nicknamed, endlessly sticking their rows of new stamps in an album which can be arranged in any subjective order. But zoology has still a very important epistemological role to play. The progressive evolution from amoeba to man might appear to be nonexistent for those who are using strictly zoological criteria. Yet there was no progressive increase in complexity in the kingdom of the bacteria or protists. Plants and fungi have achieved a level which is not higher than that of the diploblastic, tissue-level animals. Evolution in these two kingdoms did not lead to any spectacular, qualitative changes in complexity and function of the living matter. It is within the animal kingdom that we are witnessing the tremendous evolution from the single...