FUNCTION AND ADAPTATION IN PALEONTOLOGY AND PHYLOGENETICS: WHY DO WE OMIT DARWIN?

Darwin not only presented his theory of descent with modification as an answer to the riddle of the pre-evolutionary concept of "natural groups," he also repeatedly emphasized that most of this descent ("transmutation," as he called it; evolution) was through adaptive modification. Although this has been amply confirmed in the twentieth century, methods used to estimate evolutionary history (phylogeny) have at first either overlooked its rigorous applicability, or later simply disregarded it as irrelevant. Furthermore, a school of functional analysis has opted for the omission of adaptational analysis altogether, contending that such an undertaking is not adequately "scientific." This school is now, oddly, called "new adaptationism," which focuses on what it calls "causal role function." This omission of the processes of Darwinian competition and adaptation from theory and from the practice of historical reconstruction of lineages has reached its zenith (in fact, a nadir of biologically relevant analysis) in the practice of algorithm-determined phylogenetic analysis. That school also considers the concept of ancestry and the time value of fossils equally irrelevant to phylogeny estimation. The adaptive strategies of organisms (fossil ones as well) are often better understood than their exact phylogenetic relationships; both kinds of analysis, in spite of the ever present pitfalls, are equally valid and mutually interdependent scientific activities. It is argued here that an assessment of the adaptive strategies in fossil and living species (to the degree that one can determine this) whose history we want to reconstruct, offer one of the most secure ways of determining (through what has been called ecological morphology) which traits are homologously shared (i.e., because of common descent) and which are the results of convergence (i.e., evolved independently). Consequently, the estimation of phylogeny, based as it is on the recognition (testing) of homologously shared or sequentially transformed traits, is greatly helped by functional and adaptational analysis.