American Scientist

The Man Who Invented the Chromosome: A Life of Cyril Darlington. Oren S. Harman. xii + 329 pp. Harvard University Press, 2004.

Cyril Darlington was an impressive figure: Well over six feet tall with a frame to match his height, handsome and debonair, a fresh rose in his jacket lapel, Oxford's Sherardian Professor of Botany looked the part. Although he was, in his day, one of the foremost cytologists in the world, he was also an enthusiastic student of history and a devoted gardener. He learned to garden as a child and subsequently expressed this enthusiasm in the genetic garden he created at the University of Oxford and in the historic Botanic Garden there; he also planned two arboreta (both achieved). His passion to account for history in genetic terms led him to write a mammoth book, The Evolution of Man and Society (1969).

The son of a Lancashire schoolmaster, Darlington graduated from Wye College with a London University degree and found unpaid work at the John Innes Horticultural Institute, which was directed at that time by William Bateson, an "apostle" of Mendelism. Sixteen years later Darlington became director. By the time he left in 1953 (after 30 years) to assume the chair of botany at Oxford, he had built for himself and the institute an international reputation.

Like Darwin, Darlington was systematic in preserving documents pertaining to his life and work. His papers are a treasure trove for the biographer. Oren Solomon Harman has made full use of them in The Man Who Invented the Chromosome, supplementing them with interviews of surviving colleagues. The book has four main sections, devoted to Darlington's early career, his major creative period in cytology at the John Innes Horticultural Institute, his response to Marxism and to Lysenkoism (which in the 1930s resulted in some Soviet geneticists being declared "enemies of the people" and shot), and his public statements about his genetic view of man and society.

Harman encompasses this agenda in an evenhanded manner, avoiding as far as possible making personal judgments about his subject. This cannot have been easy, because Darlington's strong hereditarian and racist pronouncements, many of them laced with derision and ridicule, invite challenge. But no matter how objectionable Darlington's utterances on race, class, intelligence, culture and history, Harman keeps his cool. Instead of fulminating, he lets his sources mete out the judgments. At the end he muses on the story he has told: "No one can remain indifferent" to it, he opines, or to "the lessons it offers about the interplay of ideas and the way we express and act on them." For Harman, "the passionate expression and vigorous challenge of new ideas, and their application to society, is where the future of mankind lies."

The title of the book signals the disputed status of the chromosome in the 1920s and points toward the imaginative and creative synthesis of the subject that Darlington achieved. By the time he entered the field in 1923, a consensus had developed regarding how chromosomes assemble at the onset of cell division and then split in two, with each daughter chromosome traveling to opposite poles of the cell. But the division process leading to the formation of the sperm and egg was disputed territory. Here, like chromosomes (paternal and maternal) associate in pairs. Do they associate end-to-end or side-by-side? Using plants, Darlington established that it is the latter. He went on to sort out the puzzling case of the association of chromosomes in rings in the evening primrose, and as a theorist he both clarified and unified chromosome behavior across the board in his book Recent Advances in Cytology (1932), a tour de force. But his method, although it drew upon a wealth of data, was conjectural, involving a degree of speculation that empirically inclined biologists were reluctant to accept.

Harman brings out clearly the central feature of Darlington's conception of cytology: his view that the chromosome is a dynamic unit—a vital part of "the genetic systems" that organize and suppress to varying degrees the indeterminacy of mutation and recombination. Control of cell division, control of the degree of inbreeding or outbreeding, and control of sterility or fertility are genetically based, he thought, and the genetics of these systems is itself subject to selection, just as are the genes that determine other traits. With such a view, Darlington could not but deplore the naiveté of the population geneticists' equations, which to all intents and purposes treat the gene as an independent unit in heredity. Yet, like the population geneticists, he wanted to approach the genetic system from an evolutionary point of view. These ideas he first aired in a chapter of Recent Advances in Cytology, but in 1939 he expanded on them in The Evolution of Genetic Systems. Genetic systems, he explained, "rest on a basis of chromosomes and are related to one another by processes of natural selection." This combination of "the material basis with the evolutionary framework," he declared, "provides the only means of making sense of biology as a whole."

The greatest strength of Harman's book lies in the exposition and analysis he provides of Darlington's views on the evolution and history of man and society. It is, of course, a starkly hereditarian view, but Harman shows its organic relation with Darlington's biological conception of genetic systems.

The fact that until now there has been no full-length biography of Darlington underlines the extent to which he has been forgotten. The molecular revolution left him behind, and the political climate rendered his views on man and society increasingly unacceptable. Harman's biography is therefore especially welcome. It is a valuable source for the student of the biology of the first half of the 20th century, and Harman's discussion of Darlington's genetic approach to the historical and social realms is penetrating.

No biography of a cytologist is likely to make an easy read. Cytogenetics is a very visual science. Those unfamiliar with its jargon and visual content will need more assistance than Harman has provided. Without helpful photographs of the stages in meiosis as seen through the microscope, it is difficult for the uninitiated to grasp why interpreting them proved so difficult. Also, Harman would have been wise to focus more strictly on the relation between Mendelian heredity and the chromosomes rather than including the Mendelian-biometric debate and much else. That said, he has provided a scholarly, powerful and at times devastating, but also subtle, analysis of his subject.—Robert Olby, History and Philosophy of Science, University of Pittsburgh