BOOKS MAY 2, 2005
The Man Who Invented the Chromosome:
A Life of Cyril Darlington
By Oren Solomon Harman
(Harvard University Press,
329 pp., $49.95)
In the half-century after the identification of the structure of DNA in 1953, a generation of biologists forged the revolution of molecular genetics. They deciphered the genetic code, invented biotechnology, and found themselves entangled in the high-stakes and sometimes tempestuous politics of genetics and society. A few won Nobel Prizes, a number gained fame and wealth, and all achieved iconic status for their involvement with DNA, the revolution's emblematic molecule. But if they achieved much, it was because, like Newton, they stood on the shoulders of giants, the leading biologists who in the decades after the rediscovery of Mendel's laws in 1900 established the field of classical (as distinct from molecular) genetics. These researchers worked out the mechanisms of Mendelian heredity, reconciled them with Darwin's theory of evolution, and applied them successfully to agriculture and not so successfully to human beings. And they, too, became embroiled in politics, campaigning for eugenics, where biology confronted human rights, and battling over Lysenkoism, where the stakes were the freedom of science in the new Soviet state.
This first generation was multinational, but its British leaders, along with their counterparts in the United States, contributed with signature force to its scientific achievements and its political controversies. Cyril Darlington, born in 1903, grew up with Mendelism. He was a peer in what Oren Solomon Harman rightly calls the "great founding school" of British genetics, which also included William Bateson, J.B.S. Haldane, Julian Huxley, and Ronald Fisher. Darlington's obituaries referred to him as the "Copernicus" or the "Newton" of his branch of the field, which mainly comprised genetics at the cellular level, particularly the behavior of chromosomes and their relationship to evolution. Politically engaged like his peers, he was among the first biologists to denounce Lysenko and to indict the Soviet Union for persecuting Lysenko's enemies. Yet for all his prominence, Darlington has been forgotten. It is not simply that he has been obscured by the dazzle of DNA. It is also that later in life he embraced a degree of hereditary determinism and a contempt for the welfare state that made him appear to be, as Harman puts it, "a dinosaur, a crank."
Harman's brilliant book—the first and, almost surely, the definitive biography—wrests the earlier Darlington from the later crank, recovering him as a human being and restoring him to scientific eminence. Drawing on Darlington's voluminous papers, correspondence, and diaries, Harman recounts the personal odyssey that took his subject from a bleak childhood to high achievement in the new genetics; his scientific and political engagements, particularly his differences over Lysenko with his fellow biologists, many of them on the left; and his slide into the cantankerous biological conservatism that marked his later years. Harman writes in supple prose and with capacious discernment, providing a portrait of the man that is at once empathetic and critical, a study in character and personality that illuminates his science as well as his personal and professional lives.
Darlington was an unwanted second son (his father marked Cyril's birth by moving permanently out of his mother's bed). The senior Darlington, a former schoolmaster who worked for a chemical company near London, was harsh; the mother was straitlaced. Cyril left for St. Paul's School in London, and then attended an agricultural college, where he discovered Mendelism. In 1923, he went as a junior researcher to the John Innes Horticultural Institution, at Merton in Surrey, which William Bateson, its head and an early champion of Mendelism, was turning into a major center in "genetics," a word that he coined. Darlington got hooked on chromosomes when he first saw them through the microscope of a staff cytologist.
Chromosomes, so named because they take on color when stained, reside in the nucleus of the living cell and, as was well established by the 1920s, are the bearers of heredity. (In current terms, they comprise DNA embedded in protein.) In the quiescent cell, they form an undifferentiated mass, but in the dividing cell they disentangle themselves and perform a variety of maneuvers, one set of which is characteristic of the regularly dividing cell (mitosis) and another, of the sexually dividing cell (meiosis). In meiosis, for example, similar chromosomes find and pair with each other, lining up or forming a physical cross (a "chiasma"); they also exchange genetic information, a process dubbed "crossing over" or "recombination." How they managed their maneuvers was pretty much disputed and mysterious when Darlington arrived at the John Innes.
Darlington soon set out to clear up the mystery, investigating pairing first in hyacinths, then in tulips. Harman suggests that he found serenity and solace in peering through the microscope—an escape from his father's insults and his mother's moodiness. The work progressed well, and he grew increasingly self-assured. "At the age of 18 most of the world seemed stupid and annoyed me; at 24 I know it is stupid and it ceases to worry me," he wrote. In 1931, generalizing from his observations at the microscope, he concluded that crossing over was linked mechanically via chiasmata to pairing and, indeed, to the entire integrated process of sexual reproduction.
Further study of chiasmata formation convinced him that genetic crossing over must occur in all organisms and that it figured in evolution. To no small degree, the field of genetics had grown out of experimental programs designed to resolve certain conundrums raised by Darwin's theory, particularly the question of what natural selection acts upon. The first generation of geneticists, remaining absorbed by the puzzles, recognized that genetic mutation supplied material for natural selection. Darlington, who was also attentive to evolutionary issues, contended that natural selection could act as well on the new genetic combinations produced by crossing over. He also held that chromosomes and their behavior were themselves products of the evolutionary process. As Harman, who lucidly conveys Darlington's science, puts it: "Not only did heredity lead to evolution … heredity itself was subject to evolution."
Darlington summarized his chromosomal work and ideas in Recent Advances in Cytology, published in 1932 to high praise from Haldane, an exacting critic. But while the book was, as Harman observes, a "masterpiece," the responses from many cytogeneticists ranged from cool to hostile. Harman insightfully parses the reaction. Cytology, like most of biology, was a strongly empirical science, closely tied to what the microscope revealed; but Darlington's claims were often deductive. Then, too, the great American geneticist Thomas Hunt Morgan, who won a Nobel Prize in 1933 for his group's pioneering elucidation of the mechanism of Mendelian heredity, tended to take the chromosome for granted, in contrast to Darlington's insistence that it operated under genetic, and thus evolutionary, control.
Most disturbing was Darlington's propensity to theorize, his willingness to lace his book with cascades of conjectures. Harman points out that Darlington admired the great German biologist August Weissmann, who in the late nineteenth century forged disparate observations concerning the stuff of heredity into the construct of germ plasm, and who declared that "the time in which men believed that science could be advanced by the mere collection of facts has long passed away." In his research on chromosomes, Darlington, too, had faced "a mass of unruly observations," Harman notes (much the same, one might add, as contemporary biologists confront a mushrooming catalogue of genes). Harman observes that Darlington, like Weissmann, considered theorizing, if not an expression of truth itself, a way of laying out a road map to reach it.
Struggling against the current sandstorm of genetic data, biologists today have grown more sympathetic to theorizing, spinning computerized hypotheses from genetic data banks. Biologists in Darlington's day resisted theorizing. Conjectures were all right if associated with abundant facts, one reviewer of Recent Advances in Cytology carped, adding: "But the ratio of facts to conjectures should be kept in the ratio of food to wine. We know what happens when the wine is in excess." Some geneticists thought that Darlington had imbibed too much. He "was better at thinking up an idea than actually proving its truth experimentally," Harman writes. Resistance was also directed against the strong connection that Darlington found between cytology and evolution. Many geneticists disliked his claims for the role in evolution of recombination partly because they were conjectural and often untestable.
Still, cytology before Darlington had been merely an assistant to genetics. Harman argues that by unifying cytology into a theoretical whole, he helped to foster its recognition as a full partner. On the evolutionary front, particularly the modern synthesis of evolution and genetics that emerged by 1940 and to which Haldane, Fisher, Huxley, and the American Sewall Wright mightily contributed, the future was with Darlington. The late Ernst Mayr, a grand master of the field, noted that "no one made a greater contribution to the understanding of recombination and its evolutionary importance than Darlington."
Darlington alienated many biologists, dismissing cytological data-gatherers with ridicule. He was a contentious man. Harman finds in him a strong tendency to mock middle-class conventions, especially those embodied in his parents. Strapping and handsome, he was a promiscuously successful lover at the John Innes. In 1932-1933, when he was thirty and on a fellowship year in the United States, he married a free-thinking history teacher at Vassar, who had suggested matrimony after a few days of courtship so that she could bear his child. When his mother wrote to disapprove, he responded that he and his bride had bathed in the nude on a Cape Cod beach. The couple soon parted, obtaining a divorce two years later in Reno.
Yet there was a harsh streak in Darlington's character, something more than anti-bourgeois rebelliousness. In 1937, in Scotland, he married an English botanist, who in England, where his Reno divorce was unrecognized, was his common-law wife. As such, she had none of a wife's rights under English law, a lack of status that he invoked when, in 1949, he left her and the five children they had produced to marry one of the couple's friends, refusing at first to pay not only alimony but also child support. The pairings he lived were not as admirable as the pairings he studied.
All the while Darlington flourished at the John Innes Institution, a vital center in genetics, evolution, and cytology with a cocky staff who were, as Harman notes, "young, smart, and leading the way." Among them, on a regular part-time basis from 1928 on, was Haldane, a rugged aristocrat, brilliant mathematical geneticist, intellectual iconoclast, and social rebel who was moving steadily leftward and in 1942 joined the Communist Party. At the time, Darlington also had strong leftist tendencies, faulting eugenics because of its "arbitrary" distinction between desirable and undesirable classes and indifference to the way environmental variations affected human achievement. Darlington and Haldane spent a great deal of time together discussing science, politics, and the philosophies of Marx and Engels. Eleven years Haldane's junior, Darlington found Haldane's qualities appealing, and remembered that for a long while "I regarded him as my infallible mentor." In the 1930s, he considered Engels's dialectical materialism a useful heuristic tool for science and endorsed rational state planning to exploit science for good social purposes.
Then came the battle over Lysenko, Stalin's protégé, who contended in neo-Lamarckian fashion that organisms such as winter wheat could be genetically modified by changes in their environment in ways that would transform Soviet agriculture. Lysenko denounced so-called Mendelism/Morganism as erroneous and a tool of bourgeois science. Some of its advocates were imprisoned, exiled, or shot. Many geneticists in the United States and Britain recognized Lysenkoism as a travesty, but while they were willing to expose its unfounded science, Harman emphasizes, they preferred to treat it publicly in the Soviet context as "an isolated scientific aberration." They shied from attacking the political structure of Lysenkoism because they did not want to discredit the Soviet state and its role in science. Such a political calculus was privately expressed by the American geneticist Herman Muller, a socialist who had gone to work in the Soviet Union in the mid-1930s and felt increasingly endangered by his staunch defense of Mendelism/Morganism. Fleeing on a train to Spain in March 1937, he wrote to Darlington that he would not "tell the truth to the world about the situation there. It would be too damaging to the opinion of scientists about the U.S.S.R.… I do not want to become an agent of anti-Soviet propaganda."
Darlington had no such reservations. An unalloyed disbeliever in the Lamarckian inheritance of acquired traits, he was offended by "the fakes or fancies of Lysenko" and outraged by Stalin's political persecutions, especially of his friend Nikolai Vavilov, a prominent Russian geneticist who died in a Soviet prison during the war. In an article written in 1946, he scathingly criticized Lysenko's doctrines and the Soviet oppressions conducted in their name, declaring that in the Soviet Union "we see indeed the official overthrow of truth and reason … no less official than that in Hitler's Germany.' The editor of Nature, calling the piece "undesirable," declined to publish it, and so did the editor of the Fortnightly Review, explaining that he was "fearful of being thought a stumbling block to better relations between the countries." After the piece appeared in a minor scientific magazine, it caught the admiring attention of George Orwell, who arranged for its appearance in a magazine of broad circulation. It prompted dissents, some of them wrathful, from several prominent biologists and the communist left.
The apologists continued in force even after the Communist Party Congress in Moscow in August 1948 adopted Lysenko's biology as the party's official biology. To be sure, Haldane, who had wanted to believe that the reports of the disappearance of Soviet scientists were the products of vicious rumors spread by enemies of the Soviet Union, now left the party. And Muller resigned from the Soviet Academy of Sciences, blasting the Soviet Union for its attempt to establish "a politically directed 'science,' separated from that of the world in general, in contravention of the fact that true science can know no boundaries." Still, Harman notes, Haldane was the only prominent Marxist scientist in Britain to quit the party.
Harman wonders why Darlington's reaction to Lysenkoism diverged so sharply from that of his colleagues, even the non-Marxist ones. One reason was his growing disillusion with Haldane: his irritable persona, his formalist genetics, and his evasive politics, particularly his persistent refusal, until 1948, to face up to Lysenkoism. Harman likens Darlington and Haldane to two ideological travelers who approached each other, resonated for some years, and then proceeded on their respective journeys. Darlington's enthusiasm for Soviet Marxism began waning just as Haldane's enthusiasm was waxing. Their ideological differences were compounded by their rivalry, beginning in 1936, for the directorship of the John Innes, to which Darlington was appointed in 1939. Darlington had become his own man, and he no longer wanted Haldane's mentorship.
Harman finds that Darlington's reasons for attacking Lysenkoism reached deeply into his own evolving views on the role of science in shaping the human future. His political journey past Haldane was taking him to the right. If in the 1930s he had embraced state mobilization of science for socio-economic development, in the 1940s, having come to hate totalitarianism, he increasingly rejected such direct state intervention, especially the Soviet version. At bottom, Harman writes, his belief in "the biological diversity of man" was growing, and so was his "disbelief in the possibility of changing [man's] nature by anything other than biological means." The belief and the disbelief were coming into direct conflict with both the Marxist goal of egalitarianism and its credo that human beings might be improved by modifying their socio-economic environment.
By the late 1940s, Darlington had become, in Harman's description, "a racialist scientific humanist, convinced that genes determine behavior, skill, and intelligence, and that if scientifically guided social planning were to ignore the inherent biological differences in capacity and function between people and races, it was bound to fail." He first advanced his racial genetic determinism in the early 1940s, even while Hitler was visiting his excrescences on Western civilization, and drew on complicated arguments concerning race, class, and mating in human evolution that Harman skillfully elucidates. He held that human capacities and behavior, including intellectual and cultural character, are grounded in genetics. Human evolution thus proceeded optimally under the parallel conditions of inbreeding (segregation of groups by race and class) and outbreeding (intermixing across groups that would produce a kind of intellectual and cultural hybrid vigor). For Darlington, the division of human beings into races and classes was evolutionarily advantageous, provided the division was unstable, and those who sought to proscribe discussion of genetic differences among races and classes offered the "council of timidity and escape."
Darlington expected that this line of argument, which undergirded much of the rest of his life's work, would get him into trouble. But he relished the role of the enfant terrible, the disturber of the ideological peace, duty-bound to make people realize that a system committed to human equality would be doomed to fail and evolutionarily counterproductive. He found a target in the Statement on Race that UNESCO issued in 1950. Drafted and revised by a number of leading geneticists and social scientists, the document dismissed the concept of race as scientifically meaningless and claims for the connection of genes and culture as lacking scientific support. Harman takes the statement as an expression of the day's politically correct science, suggesting that it rested on "dubious scientific ground" and that its signers were willing to bend "Mendelism and Darwinism in the service of antiracism." He misrepresents some of the document's essentials, writing that it "rejected the notion that races differed in mental capacity." It asserted, in fact, that IQ tests "do not in themselves enable us to differentiate safely between what is due to innate capacity and what is the result of environmental influences," and it pointed out that what people often identified as racial differences were differences in ethnicity, nationality, or religion. Still, Harman rightly observes that little direct scientific evidence existed for several of its claims. And the statement did signal the emergence of what he calls "a powerful consensus against discussion of genetic determinants of racial differences," which raised a red flag to Darlington.
Darlington responded to the statement in a book that he called The Facts of Life, contending that different races would always differ, that where race crossing was disadvantageous it should be prohibited, and that the homogenization of the races should be avoided lest it foreclose consideration of how the diverse capacities of each race might be used for the benefit of all races. He also contended that behavioral traits such as criminality, reason, imagination, and success in school and even in marriage were not the products of acculturation and habit but of genetics. Reviewers of the book denounced it as scientifically unfounded, biased, and in some respects ridiculous—for example, his attribution of the evolution of social class in Britain over fifteen hundred years to a polymorphism (a variant in several genes across the population). Muller, who had also been disturbed by the "exaggerated" UNESCO statement, nevertheless told his friend Darlington that, in his view, "differences of historical background have played much the largest role in the observed behavior differences between peoples."
In 1953, Darlington accepted a professorship at Oxford University, which he hoped would provide an advantageous platform for the promotion of his theories of human evolution. He tried to remake biology at the university by integrating through genetics disparate fields such as botany, forestry, zoology, biochemistry, agriculture, and clinical medicine. He was ahead of his time in such an ambition, but he was also handicapped in realizing it by his cutting sarcasm and his resistance to the new molecular biology of DNA. In 1964, he told an interviewer that the strongest motivator in his personality, apart from curiosity, was "indignation."
Undaunted by the negative reaction to The Facts of Life, Darlington continued to work on its contentious subjects, bringing the fruits of his labors together in The Evolution of Man and Society, a magnum opus of some seven hundred pages that was translated into many languages. Published in 1969 amid the turmoil over race in both the United States and Britain, including the National Front's anti-immigrant movement, it advanced a sweeping genetic determinism that identified the book and its author with the racist right. So, similarly, did his associations with various professional groups and journals, and so did his last book, The Little Universe of Man, which appeared in 1978, three years before his death, and railed against the welfare state, trade unions, communitarianism, and what he termed the "taboo on the study of hereditary differences."
The behavioral biologist Konrad Lorenz, an intellectual collaborator of the Nazis, praised the book, and so did Ernst Mayr, evidently a closet inegalitarian, who wrote to Darlington, "I am delighted you have said all these things which are so true but which are simply suppressed in the 'egalitarian' mass media. … I am frank to say, your bias, or I should say government policies based on your bias, should promise a far better future for mankind than the ruling bias." Revealingly, as Harman points out, these kudos were delivered privately. The public response of the critics ranged from intellectual condemnation to personal vituperation. Among most mainstream scientists the book sealed Darlington's reputation as a racist crank.
Indeed, as Harman observes, he was by then "a man out of time," or worse, "little more than an ideologue masquerading as a scientist." Many people in and out of science agreed with Karl Popper, who remonstrated to Darlington that even if men are born unequal in talents and character, "we ought to treat them as far as the law and public institutions are concerned as equal." Political philosophy aside, advances in evolutionary theory and human genetics had increasingly discredited Darlington's scientific reading of race.
Harman points out that Darlington's methods—his reliance on theory at the expense of data—were both his strength and his undoing. It led him sometimes in his contrariness and enthusiasm to "ideas unsupported by well-established fact." "All my life I have been trying to tie things together," Darlington once wrote, "using or finding ideas that will help to make small bits into larger bundles.… It makes friends critical, critics angry and enemies furious." That acknowledged, Harman wonders whether the fact that his contemporaries never granted him the respect they gave to Haldane, for example, and that he has been forgotten, may say as much about the intellectual tolerance of his audience as it says about Darlington.
Harman sympathizes with the view of Darlington's friends that he was not a racist, noting that he rejected notions of a hierarchy among human groups as nonsense and endorsed not only the segregation of the races but also their mixing as the promise of evolutionary survival. His genetic determinism might have made him a eugenicist, but he was too persnickety and too averse to evangelical causes to join any movement, particularly one for human biological improvement to a uniform standard. Rather, his theory of evolution led him to value human diversity and to urge protection of the natural environments that sustain it.
As a stern critic of Soviet persecution, Darlington had been ahead of his time, at least among the British scientific left. As an environmentalist, he was with his time. And Harman counts him as having been ahead of his time in insisting that genes are related to behavior. While race is no longer "a viable biological category," Harman remarks, "the claim that genes have nothing to do with behavior has to be abandoned." Human society is shaped by both genetic and cultural forces. Darlington "took this way of thinking too far, but he was pointing in an important direction." Harman here may be too generous to Darlington. A genetics of behavior was born with the eugenics movement about the time of Darlington's birth. Crude and racist at the outset, it has been beset by both epistemological difficulties—how to tease out the contributions of genes from the influences of family, school, and culture?—and social bias for more than a century. But given that it remains a moral and social minefield, Harman's plea for intellectual tolerance is timely. He might have added that negotiating the field needs to be coupled with a more sensitive regard for social fact, implied stigmatization, and the deep epistemological difficulties of human behavioral genetics than Cyril Darlington ever displayed.
Daniel J. Kevles teaches history at Yale. His books include in the Name of Eugenics: Genetics and the Uses of Human Heredity (Harvard University Press).
This article originally appeared in the May 2 & 9, 2005, issue of the magazine.