On Exact Methods in Systematics

The author expounds the main ideas and methods of his conception of exact systematics. The leading principle of his system is an objective evaluation of characters according to their frequency. Thus, the author calls in question the Adansonian principle of equal weights of characters. The indices recommended by the author-indices t-serve for quantitative characterization of taxonomic relationships as well as for evaluating the originality of objects under consideration. The problem of partition of taxa (in general form) is also discussed in the article, and some examples illustrating the recommended methods are given. NECESSARY PBE-CONDITIONS Before taking up the problem of exact methods in systematics it is necessary to speak on certain theses concerning systematics as a whole. Without fulfilling this condition the purpose of our investigation will be left unclear. What does the existing systematic hierarchy of organisms represent? From my point of view the system reflects the real regularities of living nature, to a greater or lesser degree of completeness and perfection. At first sight the natural multiformity of life may seem rather disorderly, but after thorough consideration even a layman will notice that plants and animals can be ordered according to degree of mutual similarity into separate groups, the borderlines of which are in many cases so well-defined that the groups can be identified quite easily. Hardly anyone will doubt that such group notions as "bird" or "beetle" became current long before any form of science had emerged. A stricter scrutiny of multiformity will permit establishment of another regularity, the hierarchical coordination of groups. We consider the existence of hierarchic groups to be a universal feature of biological systems and one of the most important laws of nature. It is significant that all attempts to build a system of organisms on a non-hierarchic basis, for instance in the form of combinatorics or periodics, have failed, while the hierarchic system has become part and parcel of biology. Nonetheless, there exists another point of view, contrary to the one above. The followers of that viewpoint consider the existing system to be no more than "a figment of human imagination," which has no counterpart in nature. In my opinion such a view is an attempt to discredit systematics as a science. Indeed the value of science lies first and foremost in its objective character, in discovering objective laws of nature. If the system of taxa is merely a collection of subjective "figments," it loses any scientific interest and may serve at best only as a more or less convenient catalogue. At the same time, a phylogeny based on the natural system will prove discredited. Is there any sense in investigating the origin of classes of birds or insects if both of them exist only in our imagination? In this case the question would only be about the evolution of the "figments" of our imagination, and that is all. The second basic thesis touches upon the problem of the interrelation of the system and phylogeny. Very often one hears that the system must be phylogenetic. This premise must be subjected to analysis because the essence of it is not clear. Proceeding from the theory of evolution we have every right to state that the existing system of organisms is the result of evolutionary, historical development of the organic world. Of course, this premise is justified only when we have in mind a natural system, i.e., a system answering natural regularities and not arbitrary re-