Cladistic Methods in Textual, Linguistic, and Phylogenetic Analysis

Abstract

Platnick, N. I. (Department of Entomology, American Museum of Natural History, New York, New York 10024) and H. D. Cameron (Department of Classical Studies and Museum of Zoology, University of Michigan, Ann Arbor, Michigan 48104) 1977. Cladistic methods in textual, linguistic, and phylogenetic analysis. Syst. Zool. 26:380-385.-The concept that historical interrelationships can be demonstrated only by the presence of shared innovations is fundamental to the fields of textual and linguistic, as well as phylogenetic, reconstruction. All three fields utilize analogous procedures in which data are organized into transformation series of homologous character states, the polarity of these transformation series is determined by out-group comparison, and shared innovations are used to construct internested series of three-taxon statements that operate at a level of generality above that of specific ancestor-descendant hypotheses. acceptance of these methods as the standard operational tools in separate fields suggests that cladistic analysis is a general comparative method applicable to all studies of historical interrelationships based on ancestor-descendant sequences, and that biologists concerned with such questions can ill afford to ignore cladistic theory and methods. [Phylogeny reconstruction; phylogenetic systematics; cladism.] The function, indeed the expressed purpose of taxonomy is to discover, to define, and to elaborate the methods that may best be used to produce an acceptable classification of the animal kingdom. implication of this function is that taxonomy is to be regarded as a science in its own right, with fundamental concepts, some at least of which ought to be applicable to the classification of objects of any kind, and should not be confined to the organisms with which biological taxonomy alone deals. -T. H. Savory (1970:91) Recent years have seen an increasing awareness and use among zoological systematists of the theory and methods of phylogenetic analysis (cladistics) developed by Hennig (1950, 1965, 1966). These methods have been well defended by Wiley (1975) from the point of view of Popperian hypothetico-deductive science. Critics, both of the methods themselves and of their application to classification, have not been silent, but have usually had their own previously conceived axes (the pheneticism of numerical taxonomists or the pseudophyleticism of evolutionary systematists) to grind. purpose of this paper is to point out a fact overlooked during the controversy, namely, that methods analogous to those of Hennig are accepted as the standard tools of analysis in two other fields that resemble phylogenetic systematics in being primarily concerned with constructing and testing hypotheses about the interrelationships of taxa connected by ancestor-descendant sequences. fields referred to are 1) textual criticism (the evaluation of the interrelationships of, and choice between, alternative versions of writings that exist today in two or more manuscript forms), and 2) linguistic reconstruction (the study of the interrelationships among human languages). historical nature of linguistic relationships should be obvious; if two languages are related they have a common ancestor, which almost never is available to us in the flesh (or stone, or parchment). Indeed linguists speak, in a genetic metaphor, of a kind of social inheritance. In the simplest model, an ancestral population (for it is really populations that descend from one another, not languages) speaking a single unified language splits, through migration for instance, into two isolated populations no longer in communication. In time, since language always changes, and always changes systematically throughout a population, the speech of the two groups no longer in communication will change, and not in the same way in which it