Jordan, (Heinrichernst) Karl

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(b. Almstedt, near Hildesheim, Germany, 7 December 1861; d. Tring. Hertfordshire, England, 12 January 1959)

entomology evolution.

From the 1890’s to the 1930’s Jordan was the world’s foremost animal taxonomist. He was the youngest of seven children of a farmer who died when Karl was five. The generosity of an uncle enabled Jordan to attend high school at Hildesheim and the University of Göttingen, where he received a training in the best tradition of German botany and zoology. Among his teachers was Ernst Ehlers, a distinguished comparative anatomist of invertebrates, who brought him into contact with the battles concerning the causes of evolutionary change then raging among August Weismann, Ernst Haeckel, Theodor Eimer, Wilhelm Haacke, and others. In 1866 Jordan received his Ph.D. summa cum laude.

After a year in the army. Jordan acquired a teaching diploma and in 1888 began to teach in the gymnasium at Münden. In 1891 he married Minna Brünig; she died in 1925. At Münden he was in active scientific contact with several local biologists, one being the ornithologist Count Hans Berlepsch. In Berlepsch’s house he met the future director of the Rothschild Museum. Ernst Hartert, and a close friendship soon developed between them. It was Hartert who in 1892 persuaded Lord Walter Rothschild to engage Jordan for his private museum at Tring, Hertfordshire, England which Jordan joined in 1983, beginning a brilliant career extending over more than sixty years. During the next forty years Hartert was the outstanding ornithologist in the world, and Jordan the premier entomologist.

Since his early school days Jordan had been an enthusiastic naturalist and beetle and butterfly collector. Relieved of all teaching duties, he could now devote himself entirely to his taxonomic researches. Although his Ph.D. dissertation dealt with butterflies, his main activity from 1886 to 1895 was devoted to beetles. Among his bibiography of more than 450 papers, more than a third are devoted to the Coleoptera, particularly the family Anthribidae. His first major contribution to the Lepidoptera, part of a paper written with Lord Walter Rothschild, dates from 1895. This was followed by monographs on Papilio, Charaxes (1898–1903), and the Sphingidae (1903). The latter has been characterized as “possibly the finest example of a taxonomic monograph that has ever been produced in Lepidoptera,” In contrast with other contemporary authors, who based their classification primarily on color pattern. Jordan took numerous anatomical and behavioral characteristics into consideration, producing classifications that have stood the test of time remarkably well. Among the more than one hundred publications on Lepidoptera in the ensuing fifty years are many important monographs on genera and subfamilies, but none as lavishly illustrated as those on Charaxes and the sphingids.

Beginning in 1906, Jordan published papers (up to 1923, mostly in joint authorship with N. Charles Rothschild) on fleas (Siphonaptera). He was soon the world’s outstanding authority on this group. The more than 1, 280 figures in 140 publications on fleas were all drawn by Jordan himself. His reclassification of this previously chaotic order of insects is now largely adopted. As in other parts of his taxonomic research. Jordan constantly asked profound biological questions. How are specializations in certain species and genera of fleas connected with the structure of hair of feathers of the hosts? Among the abundance of variable characters. which best indicate close relationship? What contribution do fleas make to zoogeography? Taxonomy for Jordan was always a means to an end.

Jordan’s taxonomic publications were in a class by themselves. The accuracy of the descriptions and figures was matched by a careful population analysis of large series of specimens; allopatric “species” were carefully studied for the possibility of conspecificity; synonymies were conscientiously complied; and, most of all, the totality of characters was carefully evaluated in order to determine relationship.

Jordan’s greatest contribution, however, was his development of the principles of population systematics in a series of papers (1895, 1896, 1903, 1905) issued as a deliberate challenge to the typological taxonomy prevalent—indeed, quite universal—at the time (Mayr 1955). What he promoted in 1895, in an introduction to a monograph on Oriental Papilio by Rothschild, was the gist of the “new systematics.” If systematics has by now regained some of the prestige it had in former centuries, it is largely due to Jordan’s pioneering contributions. Eventualy most evolutionists agreed with his claim “Sound systematics are the only safe bases upon which can be built up sound theories as to the evolution of the diversified world of live beings” (1910, p. 385).

Jordan was particularly emphatic about the distinction between individual and geographical variation. Being a strict believer in allopatric speciation, he considered only subspecies (“geographical varieties”) as incipient species. In a series of papers he attempted to refute the claims of sympatric speciation frequently made by other entomologists. Just as he believed in comprehensive polytypic species, so he also believed in large genera. Like most distinguished taxonomists.Jordan was definitely a “lumper.” As a taxonomist, he frequently had to make decisions as to the relationship of a species or genus and the best way to subdivide a higher taxon. He was almost a genius in finding the best solution, inducting Walter Rothschild once to remark, half admiringly, half despairingly: “Oh, he is always right.”

Jordan was very modest, never pushing himself forward, but his merits were so fully appreciated that he was eventually made honorary life president of the International Congresses of Entomology and of the International Commission of Zoological Nomenclature, and a fellow of the Royal Society, to mention only a few of his many honors. He was immensely helpful to other workers and played an important role after World War I in reviving good relations among the entomologists of the formerly warring nations. Also notable is the help that he gave Lord Rothschild in building up the world’s greatest collections of butterflies and fleas.

Jordan enjoyed remarkably good health into his old age. Well into his eighties he collected butterflies and fleas in the Alps, and at age ninety-three he studied the complex genitalic structures of fleas through the microscope and drew the illustrations for his papers with a steady hand. He died at ninetyseven after a short illness.


1. Original Works. Many of Jordan’s monographs, although published in the Tring Museum journal. Novitates zoologicae, are virtually books—for example, the monograph on Charaxes (1898–1903) and the revision of the Sphingidae (1903), both written with Walter Rothschild. Other important papers are “On Mechanical Selection and Other Problems.” in Novitates zoologicae, 3 (1896), 426–525; “Der Gegensatz zwischen geographischer und nicht-geographischer Variation.” in Zeitschrift für wissenschaftliche Zoologie. 83 (1905), 151–210; “The Systematics of Some Lepidoptera… and Their Bearing on General Questions of Evolution,” in Proceedings of the International Entomological Congress. I (Brussels, 1910), 385–404; and “Notes on Arctiidae,” in Novitates zoologicae, 23 (1916), 124–150.

II. Secondary Literature. There is a festschrift for Jordan in Transactions of the Royal Entomological Society of London. 107 (December 6, 1955). 1–402, with a biography by Miriam Rothschild and evaluations of Jordan’s contribution to the knowledge of fleas (Robert Traub), anthribid beetles (E.C.Zimmerman), lepidopterans (E.G.Munroe), and systematics and evolution (Ernst Mayr), and a bibiography to 1954. See also N.D.Riley, “Heinrich Ernst Karl Jordan.” in Biographical Memoirs of Fellows of the Royal Society. 6 (1960), 106–133, with bibliography; and Miriam Rothschild. Dear Lord Rothschild (London, 1983), with an account of Jordan’s role at Rothschild’s museum.

Ernst Mayr