Several stages can be identified in Darwin's effort to formulate natural selection. The first stage corresponded, roughly speaking, to the period up to 1844. It was characterized by Darwin's attempt to base his model of geographic speciation on an individualistic dynamics, with species understood as reproductively isolated populations. Toward the end of this period, Darwin's ignorance of the laws of variations and heredity led him to adopt varieties and species as the units of variations. This had the extremely important effect (...) of stimulating him to consider the process of speciation as involving populations. At the end of this period, Darwin also began to regard adaptation as being exclusively toward places in the economy of nature. Thus he faced the problem of integrating the process of natural selection with the process of speciation. Individual variants were the units that fueled the first process, whereas varieties produced new speices. There was no link between adaptation and speciation, except whatever could be supplied by a quasi-historical, developmental idea of optimizing the amount of life.In the second stage, I contend, Darwin's reading of Milne-Edwards crystallized his previous insights into a coherent whole. Milne-Edwards' comments on the advantage of functional specialization could readily be understood in terms of the advantage accruing to the individual, relative to other members of its species, from occupying a different niche. Milne-Edwards' discussion of the division of labor suggested that organisms which moved into unoccupied niches would enjoy reduced competition, and hence a differential advantage in survival and reproduction; thus they would induce the species to do likewise. Rather than base his explanation on an analogy with the artificial economy, Darwin chose the principle of the optimalization of the amount of life per unit area as the overall explanatory principle. The difficulties connected with integrating different levels of description were therefore circumvented, insofar as the problem of diversity and speciation was concerned. Although natural selection considered individuals as the units of selection, and the units of variations were varieties and species, the dynamics of the process understood in terms of natural selection, competition, division of labor and niches could give a plausible account of how individual advantage could be transferred to the species, and how diversity resulted from this mechanism. The problem of the different levels of descriptions was confined to how the properties of variations in individuals (in particular, the frequency of variations and their transmission) were responsible for the assumed variability characteristic of varieties and species. This problem Darwin never solved.A third stage occurred in 1858 with the amalgamation of the tree-of-life vizualization of the process of speciation. Speciation, geographic distribution, and systematics were all then embedded in a conceptual matrix with vast explanatory powers. (shrink)

WhenVestiges of the Natural History of Creation, the anonymous evolutionary work which caused such a furore in mid-Victorian England, was published towards the close of 1844, Richard Owen, by then well-entrenched as the ‘British Cuvier’, received a complementary copy and addressed a letter to the author. This letter and how it should be interpreted have recently become the subject of historical debate, and this paper is directed at resolving the controversy. The question of Owen's attitude to theVestigesargument is central to (...) the larger historical problem of the views of this leading British morphologist and palaeontologist on the contentious issue of the ‘secondary causes’ of species. Owen wrote so little directly on this subject prior to 1858, that the letter in question, together with his two letters of 1848 to the rationalist publisher John Chapman, and the controversial conclusion to hisOn the Nature of Limbs(1849), constitute the major evidence that Owen in this period subscribed to a naturalistic theory of organic change. On the basis of this evidence, historians of biology have generally concurred with Owen's biographer grandson that Owen had a ‘certain leaning towards the theories enunciated by Robert Chambers [the Vestiges' author]’, but that his ‘official’ anti-transmutationist stance of the 1840s did not permit full public expression of his own views. As Ruse most recently summed up this historical consensus: Owen in the 1840s was ‘moving down a path not completely dissimilar from that followed by Chambers’, and he ‘tried to have matters two ways, praisingVestigesto its author and condemning it to its critics’. (shrink)

The comparative method, closely identified with Darwinian evolutionary biology, also has a long pre-Darwinian history. The method derives its scientific power from its ability to interpret comparative observations with reference to a theory of relatedness among the entities being compared. Such scientifically powerful strong comparison is distinguished from weak comparison, which lacks such theoretical grounding. This paper examines the history of the strong comparison permitted by the comparative method from the early modern period to the threshold of the Darwinian revolution (...) in the mid nineteenth century. It interprets the work of early pioneers such as Belon, Willis, Perrault, and Tyson from this methodological perspective, rather than focusing on their particular anatomical findings. Although these early writers made formative scientific contributions through their comparative investigations, the more theoretically grounded application of the comparative method by Geoffroy, Cuvier, and Owen was instrumental in laying the foundation for its later incorporation into Darwinian evolutionary theory. (shrink)

For over two centuries, the platypus (Ornithorhynchus anatinus) has been constructed and categorized in multiple ways. An unprecedented mélange of anatomical features and physiological functions, it long remained a systematic quandary. Nevertheless, since 1797, naturalists and biologists have pursued two recurring obsessions. Investigations into platypus reproduction and lactation have focused attention largely upon females of the species. Despite its apparent admixture of avian, reptilian and mammalian characters, the platypus was soon placed as a rudimentary mammal – primitive, naïve and harmless. (...) This article pursues a different taxonomic trajectory, concentrating on a specifically male anatomical development: the crural spur and venom gland on the hind legs. Once the defining characteristic of both the platypus and echidna (Tachyglossus aculeatus), by 1830 this sexed spur had been largely dismissed as inactive and irrelevant. For a creature regularly depicted as a biological outlier, the systematic and evolutionary implications of platypus poison have remained largely overlooked. In Australia, however, sporadic cases of ‘spiking’ led to consistent homologies being remarked between the platypus crural system and the venom glands of snakes. As with its reproductive reliance upon eggs, possession of an endogenous poison suggested significant reptilian affinities, yet the platypus has rarely been classed as an advanced reptile. Indeed, ongoing uncertainty regarding the biological purpose of the male’s spur has ostensibly posed a directional puzzle. As with so many of its traits, however, platypus poison has been consistently described as a redundant remnant, rather than an emergent feature indicating evolutionary advance. (shrink)

In the Origin, Darwin forwards two incompatible lines of attack on special creationism. First, he argues that imperfect or functionless traits are evidence against design. Second, he argues that since special creationism can be made compatible with any observation, it is unscientific and explanatorily vacuous. In later works, Darwin shifts to an argument that he finds much more persuasive and which would undermine theistic evolutionism as well. He argues that variation is random with respect to selection and that this demonstrates (...) that there is no design in the biological world. I examine why Darwin found the argument from independence of variation and selection more compelling than the argument from imperfection. I argue that Darwin utilized general principles of causal inference, akin to those used in modern causal modeling, to rule out any unified cause behind the evolutionary process. (shrink)

In The life of Richard Owen by his grandson there is an inference to the effect that Owen had objected to his name being used to authorize various statements that Whewell was drafting in opposition to the Vestiges. The inference is drawn from letters that Whewell wrote to Owen on 13 and 15 February 1845. Corroboration of this would corne from a letter of Owen to Whewell, dated 14 February 1845, if extant. Among the Whewell papers at Trinity College, Cambridge, (...) there are several letters from Owen to Whewell, none of which bears that date. There is one, however, dated 14 February 1844 which, on doser inspection, turns out to be the missing link in their correspondance. The evidence for the misdating is not merely that the letter falls naturally into a later sequence. The conclusion is inescapable because Owen refers to an ‘opinion which I have always entertained, and still do strongly, on the subject of a refutation of “Vestiges”’. Since the first edition of Chambers's book did not appear until October 1844, the letter must belong to the following year. My object in this paper is to examine the implications of this letter for a reconstruction of Owen's attitude to that book which Adam Sedgwick could so detest for, among many things, its ‘gross views of physiology’. (shrink)