Trees before and after Darwin

Phylogenetic trees published before Darwin’s On the Origin of Species are scarce. Lamarck (1809) and Barbançois (1816; J Phys Chim Hist Nat Arts 82, 444) are the first and only trees devoted to illustrating the genealogical connections between organisms of different species and different higher taxa. In the late 18th and early 19th centuries, most of the trees depicted in papers dealing with natural history were classifications; classifications in the shape of trees, but classifications nonetheless. Those published by Bronn (1858) are a good example. After Darwin, phylogenetic trees incorporating the time dimension flourished. In the first half of the 20th century, the Modern Synthesis failed to renew and rejuvenate the intuitive construction of trees. It wasn’t until the appearance of Hennig’s phylogenetic systematics that the real nature of the connection between phylogeny and the pre‐Darwinian concept of homology was made clear.     

Rainfall in the wet-dry tropics: Extreme events at Darwin and similarities between years during the period 1870–1983 inclusive

This paper supplements the existing climatic analyses for Darwin and the surrounding region, by providing a classification of years in terms of amount and distribution of rainfall, and highlighting the extreme, episodic rainfall events that have occurred in the period 1870 to 1983 inclusive. Approximately 77% of years have had significant departures from the two most frequent rainfall patterns and these are described. Much of the variation between years or groups of years lies in the dry and dry-wet transition periods. While the reliability of rainfall in the wet-dry tropics has been emphasized, rainfall variability over both the dry and wet seasons would seem to be an equally important characteristic, at least for the biota. In an environment such as the wet-dry tropics, where moisture is the primary limiting factor, rainfall variability has important implications for the design and interpretation of faunal and floristic surveys, monitoring programs and field experiments.     

Darwin and sexual selection: One hundred years of misunderstanding

Darwin's book on the Descent of Man and Selection in Relation to Sex (1871) is often viewed as the continuation of TheOrigin of Species published 12 years earlier (1859), both because of the implicit parallelism between natural selection and sexual selection, and because Darwin himself presents the book as developing a subject (man) which he intentionally omitted in the Origin. But the Descent can also be viewed as the continuation of his book on Variation published three years earlier (1868). Firstly because Darwin's hypothesis of pangenesis links the selection process to the origin of variation through use and disuse, an idea underlying his speculations on the origin of moral sense in humans. Second because like the action of the horticulturist on his domestic crops, sexual selection exerted by one sex on the other sex can develop fancy traits that are not easily accounted for by their utility to the selected organism itself, such as artistic taste, pride, courage, and the morphological differences between human populations. These traits are difficult to reconcile with pangenesis. They add up to other contradictions of the book possibly resulting from Darwin's erroneous inference about the mechanism of inheritance, like those on the determination of sex-ratio, or the confusion between individual adaptation and the advantage to the species. These inconsistencies inaugurate a weakening of the Darwinian message, which will last 50 years after his death. They contributed to the neglect of sexual selection for a century. Darwin however maintained a logical distinction between evolutionary mechanisms and hereditary mechanisms, and an epistemological distinction between evolutionary theory and Pangenesis hypothesis. In the modern context of Mendelian genetics, Darwin's sexual selection retrospectively appears as luminous an idea in its pure principle as natural selection, even though the mechanisms governing the evolution of sexual choice in animals remain largely unresolved.     

Theses on Darwin.

The received view that teleology has been successfully eliminated from the modern scientific worldview is challenged. It is argued that both the theory of natural selection and molecular biology presuppose the existence of natural teleology, and so cannot explain it. A number of other issues in the foundations of biology are briefly examined, while stress is laid throughout on empirical evidence of the rational agency inherent in life. It is urged that teleology be rehabilitated and that the reigning functionalist philosophy be replaced by a realistic view of biological functions as emergent properties of living matter within a broad, selforganization framework.