Between 1937 and 1940 the Taxonomic Principles Committee of the newly-founded Association for the Study of Systematics in Relation to General Biology (later the Systematics Association) attempted to define the relationship between evolution and taxonomy. The people who took part in the discussion were W.T. Calman, C.R.P. Diver, J.S.L. Gilmour, J.S. Huxley, W.D. Lang, J.R. Norman, R. Melville, O.W. Richards, M.A. Smith, T.A. Sprague, H. Hamshaw Thomas, W.B. Turrill, B.P. Uvarov, A.F. Watkins, E.I. White, and A.J. Wilmott. Most of the (...) botanists asserted that taxonomy was a practical matter to be kept distinct from phylogenetic speculation, and most of the zoologists insisted that taxonomists must strive to represent evolution if they wished to be scientific. The disagreement seemed to be hardening rather than approaching compromise when World War Two stopped the committee's work. (shrink)

Species that died without leaving descendants Darwin called ‘utterly extinct’. They far outnumber the ancestors of all living things, so they resemble the dark matter of modern cosmology, which far outweighs visible matter. He realized in 1837 that their absence is what creates the groups in a natural classification. In his Notebook B he combined the idea that species multiply with the idea that ancestors' relatives must mostly be extinct. The fossil Megatherium was utterly extinct. The iconic branching ‘I think’ (...) diagram shows extinction causing the origin of genera by eliminating intermediate species. Darwin’s concept of taxonomic ranks, starting with the genus, was informed by his interaction with taxonomists. Based on his familiarity with demography, Darwin reasoned that the survival of transitional forms was unlikely, which helped him decide to focus at the species level. When drafting his theory in the 1840s, he left out these speculative ideas, but they emerged again in the 1850s when he realized his theory needed a cause for branches to diverge. His ecological answer worked at the species level, but his Principle of Divergence was unconvincing at higher taxonomic levels. In the Origin, Darwin repeatedly insisted on the importance of utter extinction. (shrink)

The word ``deme'' was coined by the botanists J.S.L. Gilmour and J.W.Gregor in 1939, following the pattern of J.S. Huxley's ``cline''. Its purposewas not only to rationalize the plethora of terms describing chromosomaland genetic variation, but also to reduce hostility between traditionaltaxonomists and researchers on evolution, who sometimes scorned eachother's understanding of species. A multi-layered system of compoundterms based on deme was published by Gilmour and J. Heslop-Harrison in1954 but not widely used. Deme was adopted with a modified meaning byzoologists (...) leading the evolutionary synthesis – Huxley, Simpson, Wright,and Mayr. Connections are shown between Gilmour's ideas around definingthe deme, his role in founding the Systematics Association, and his chapter``Taxonomy and Philosophy'' in the book The New Systematics. Thishistorical episode raises questions about the role of carefully-definedwords in scientific practice. (shrink)