Phylogenetic Analysis of Morphological Data (review)

A naïve observer embarking on a survey of current systematic literature could be forgiven for assuming that modern phylogenetic techniques were intended primarily for use with molecular data. Abundant and easily obtained molecular characters constitute the data of choice for the majority of recent analyses. In addition, where molecules and morphology collide—as in the exploration of modern human origins—molecular analyses are often prioritized by both the scientific and the popular press.

Although some investigators have questioned the utility of morphology in reconstructing human evolution (Collard and Wood 2000), it is still the case that, ancient DNA analyses notwithstanding, molecular data are simply not available for inquiries into human evolution that involve the relationships of extinct taxa. The importance of caution and critical evaluation when selecting and analyzing morphological characters is a topic of some discussion in the paleoanthropological literature (Lieberman 1995; Strait 2001). Phylogenetic Analysis of Morphological Data, edited by John J. Wiens, provides a valuable resource for human systematists who are concerned with appropriate phylogenetic treatment of the traditional metric and nonmetric osteological characters that form the greatest part of the paleoanthropological database, as well as with other types of hard evidence.

Phylogenetic Analysis of Morphological Data, a slender volume of eight review chapters, derives from a similarly titled 1996 symposium held at the annual meeting of the Society for Systematic Biologists. These chapters constitute an important overview of theoretical problems and methodological advances in morphological phylogenetics, and their authors, who hail from a wide range of disciplines, are some of the leading scientists in the field. Unlike other books in the related literature (Hall 2001; Hillis et al. 1996), Wiens's book is not, for the most part, a how-to manual, and most of the discussions are heavily theoretical in nature. As a group of papers originally addressed to a specialist audience, most assume that the reader is a practicing systematist, already familiar with modern techniques of phylogenetic analysis. Nor is this collection a textbook, and, as noted in the preface, some topics (such as character selection and definition) are addressed in greater depth than others (such as character independence and ordering). But, because of the scope of the papers and the convenient chapter summaries, this book still provides a useful entrée to the field and to the literature, both for nonspecialists and for students. For specialists, Phylogenetic Analysis of Morphological Data constitutes a useful synthesis and summary of the current state of the field, as well as fodder for debate.

The rapidly evolving pace of molecular research can sometimes leave observers with the impression that the field of morphological systematics exists in a relative state of innovative stasis. This volume illustrates that this is not the case. The first chapter, by D.M. Hillis and J.J. Wiens, "Molecules versus Morphology in Systematics: Conflicts, Artifacts, and Misconceptions," sets the tone and tackles the strange but necessary task of defending the application of cladistic and related methods to the type of data for which they were originally intended, concluding that the two types of data are complementary, not in competition with one another. Two other chapters written or cowritten by Wiens highlight the lack of methodological rigor and transparency regarding character selection and coding that are all too common in phylogenetic analyses of morphological data (and probably also in a large portion of the molecular literature) and offer logical, operational approaches for remedying these deficiencies. Whether or not the reader agrees with these critiques, they introduce a level of reflexivity that should be particularly welcomed by paleoanthropological systematists.

P.M. Mabee's discussion of ontogeny and interpretation of morphological characters may be more relevant to larger macroevolutionary questions regarding extant taxa for which development is better documented. But other contributions that may be of particular interest to students...