Marsupials and monotremes in pre-Darwinian theory

Abstract

Pre-Darwinian biologists encountered considerable difficulty in understanding the marsupials and monotremes because contemporary theoretical explanations had developed largely without reference to these peculiar creatures. Attempts to accommodate these animals within the existing theoretical framework strained accepted explanatory theories. The failure to provide adequate explanations pointed to the limitations of existing theories and thus contributed to the development of a radically new theoretical structure--Darwinian theory.

The marsupials and monotremes presented biologists with peculiarities of anatomy, classification, geographic distribution, and fossil history which could not easily be explained within the traditional frame of reference. These same general issues were central to the theoretical debates which led to the development of the Darwinian theory of evolution. Thus marsupials and monotremes provided empirical evidence with which to test new theoretical principles. In some instances the evidence directly suggested an evolutionary approach. In other, new, unexpected evidence was easily accommodated within an evolutionary framework.

Chapter I discusses aspects of the philosophy of science (particularly the role of anomalies in the development of scientific theory) and the sociology of science (particularly the nature of colonial science) which affected the theoretical debates on the issue. Early theories of marsupial reproduction, discussed in Chapter II, provide the necessary historical background to the nineteenth-century debates. Chapter III discusses the importance of the discovery of mammals, allegedly marsupials, in the Mesozoic strata of Europe and its effect on theories of uniformitarianism, progression, and evolution. Chapter IV outlines biologists' attempts to explain the unique features of the Australian environment. Chapter V discusses the theoretical problems posed by the monotremes (egg-laying mammals) and the failure of pre-Darwinian theory to resolve these difficulties.

This study investigates the effect of the problems presented by marsupials and monotremes on the development of Darwinian theory. One cannot claim that the anomalies presented by these animals by themselves discredited pre-Darwinian biological explanations, nor can one claim that they directly pointed to the new explanatory model which would be developed. Rather, they presented astonished biologists with facts which contradicted their expectations, facts which necessarily had to be accommodated within any new explanatory system. These anomalies were manipulated by scientific adversaries to argue for or against particular theoretical models.