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The first comparisons between molecules were made a century ago by the early serologists, but the molecular age of evolutionary biology truly began with the determination of the structure of DNA by Watson and Crick (1953). As the coding relationships among DNA, RNA and proteins became clear it was apparent that these molecules contain potential evolutionary information and methods to exploit them were soon in use. At Cornell University in 1956 I began to use electrophoresis to compare blood and egg-white proteins (e.g., Sibley 1960, 1970). These studies solved few problems, but they provided experience and contacts with persons who were developing improved procedures. I tried the "agar column" method of DNA-DNA hybridization in 1963, without success. It was the hydroxyapatite technique, perfected in the late 1960's, that made DNA hybridization useful for phylogenetic research and I began to use this method at Yale University in 1974, with the collaboration of Jon Ahlquist. Between early-1975 and mid-1986, we made more than 26,000 DNA-DNA comparisons among ca. 1700 bird species, representing all of the orders and 168 of the 171 families in Wetmore's (1960) classification. A new classification was proposed (Sibley et al. 1988). Sibley and Ahlquist (1990) provide details of the history, methods and data. A book on the distribution and taxonomy of the bird species of the world (Sibley and Monroe 1990) used the DNA-based classification and a supplement was published in 1993. A brief update (Sibley 1991) included comments and corrections for several group names. Monroe and Sibley (1993) is a list of living species with brief distributional information and corrections to date.

IT IS appropriate that the views of ornithologists should be represented in this symposium because it was an ornithologist who first used trinomials to designate geographic races; it was primarily the ornithologists in this country who first espoused the concept, and it has been, I regret to say, in considerable measure due to the efforts of a few ornithologists that the subspecies has fallen into disrepute. It was Hermann Schlegel, as the coauthor with C. J. Temminck of the Aves section of Siebold's Fauna Japonica published in 1844, who first applied a trinomial combination to designate geographic subdivisions of species. There were few proponents of this system in Europe at first, but Baird, Coues, and Ridgway in the United States adopted it and applied the triple combination to geographic races. Coues even went to England in 1884 and in an historical meeting at the British Museum he tried to persuade the leading British avian taxonomists of the time to adopt the trinomial system. He was supported by Henry Seebohm but rebuffed by such potent adversaries as P. L. Sclater and R. Bowdler Sharpe. One result of this defeat was the adoption of the Code of Nomenclature of the American Ornithologists' Union in 1885. The watchword of the time was "Intergradation is the touchstone of trinominalism." By 1912, following the deaths of Sharpe and Sclater and the increasing influence of Ernst Hartert, the subspecies became as entrenched in Europe as it was in this country. It may be that history is not our purpose here but it seems apparent that the transition from the strict application of binomials to that of trinomials contains many parallels to the present situation. The problems which confronted our predecessors in systematic zoology are remarkably similar in kind, although different in degree, to those which face us today. Before attacking the subspecies concept too vigorously let us examine history once more for evidence as to its causes, its effects, and its values. In the century between Linnaeus and Darwin species were regarded as comfortably immutable and collections were still too limited to demonstrate the true range of individual and geographic variation. By 1859, when Darwin provided the theoretical basis to explain such variability, collections were extensive enough to reveal it, and Schlegel and others had indicated a method for its nomenclatorial recognition, namely, the trinomial. A modification in nomenclatorial practice was inevitable if Darwinism was to be applied. As late as 1909 Sharpe retained the Linnaean binomial in his Handlist and thereby emerged with a count of over 19,000 "species" of birds in the world. The enormous difference between this figure and the 8,600 computed by Mayr and Amadon in 1951 is an index to the differences in viewpoint of the authors and their times. We are today in a position curiously parallel to that of systematists during the transition from binomialism to trinomialism. Let us approach the present problem with an understanding of the historical background as well as of its biological significance, for it is probable that Coues and