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Pierre-Joseph van Beneden (1809–1894)

Van Beneden was a working zoologist whose career ran through parasitology, marine biology, and paleontology — and who, in his 1875 book on interspecific relations, named the categories of commensalism and mutualism and observed an “almost insensible gradation of differences” between them and the parasitic and free-living kinds.

Life

Pierre-Joseph van Beneden was born in Mechelen on 19 December 1809 and died in Leuven on 8 January 1894. He was apprenticed first to the pharmacist Louis Stoffels in Mechelen, whose natural history collection prompted his decision to study zoology. He studied medicine at the State University of Leuven, then zoology in Paris under Georges Cuvier. He became curator of the Leuven natural history museum in 1831 and professor of zoology at the Catholic University of Leuven, where he remained until his death — a career of over sixty years at a single institution. He was elected to the Académie des sciences de Belgique in 1842 and served as its president in 1881; foreign member of the Royal Society of London from 1875; honorary fellow of the Royal Society of Edinburgh from 1884. His son Edouard van Beneden (1846–1910) became a distinguished cell biologist.

Parasitology

Van Beneden’s first sustained focus, from the early 1840s, was parasitology. His work on the life cycles of tapeworms (Cestoda), beginning in 1845, demonstrated the link between adult worms in human intestines and the larval cysticerci found in pork and beef — establishing the transmission path that had eluded earlier investigators. His treatise on parasitic worms was awarded the Grand prix des sciences physiques of the Institut de France in 1858. The parasitology is the body of his career, not a preface to the later work on interspecific relations; the 1875 book emerged from decades of observing how organisms live together and at each other’s expense.

The Ostend marine station

In 1843 van Beneden established at his own expense a small marine laboratory and aquarium at Ostend — the “laboratoire des Dunes” — on the grounds of the Valcke-Deknuyt oyster farm, which belonged to his in-laws. It was one of the first marine research stations in the world, set up to avoid the long trips between Leuven and the coast with living specimens. The station gave him sustained access to the marine fauna of the Belgian coast and fed directly into the observational base from which the 1875 book was written.

Animal Parasites and Messmates (1875/76)

The terms commensalism and mutualism were introduced in 1873 in a discussion titled La Vie sociale des Animaux inférieurs. The full treatment appeared as Les commensaux et les parasites dans le règne animal (Paris, 1875), translated into English as Animal Parasites and Messmates (London, 1876).

The book is an account of interspecific relations across the animal kingdom, building on van Beneden’s parasitology. Three categories are named:

Parasitism — already in use as a term, but worked through systematically across taxa. One organism benefits at the expense of the other.

Commensalism — newly named. The commensal is an animal that shares the table without taking from the host’s provisions: “a simple place on his vessel, and does not partake of his provisions.” The image is a guest who needs only a seat, not the food.

Mutualism — newly named. Mutualists are “animals which live on each other, without being either parasites or messmates.” The category covers a range of arrangements: animals towed by others, animals rendering each other mutual services, animals affording each other asylum.

The structural observation that gives the book its conceptual weight is that these categories are not discrete kinds: there is “an almost insensible gradation of differences between parasite, messmate, and free animals.” A relationship that is mutualistic under one set of conditions can shade into parasitism under another. The categories name regions on a continuum, and the boundaries between them are not fixed.

Paleontology

Van Beneden’s paleontological work centred on fossil cetaceans, undertaken with the French zoologist Paul Gervais. Their joint Ostéographie des Cétacés, vivants et fossiles was completed in 1880. The interest began with bones of fossil whales exposed during the fortification of Antwerp. He also worked on fossil seals from the Antwerp Miocene.

Where van Beneden stops

Van Beneden’s categories are descriptive — a working zoologist’s account of how animals live together, with terms named to make the gradient of relations describable. He does not pursue questions of evolutionary mechanism; Darwin’s Origin of Species is sixteen years old by the time the book appears, but van Beneden is not in that conversation. The political and economic uses of mutualism — Proudhon from the 1840s, Kropotkin in 1902 — run parallel to his biological use and are not developments out of his work. His programme is observational taxonomy, not theory.

Key works

See also: Mutualism · Proudhon