Until this summer, I had only a vague idea of who Nikolai Vavilov was. I knew he had been Dobzhansky's mentor, and that like all Russian biologists, he had suffered at the hands of Lysenko. Otherwise, I had heard of Vavilov only in connection to an obscure quote from the introduction of Maynard Smith's Evolution and the Theory of Games:
Suppose for example, that only two kinds of wings could ever develop -- rectangular and triangular. Natural selection would probably favor the former in vultures and the latter in falcons. But if one asked 'Why are birds' wings the shapes they are?', the answer would have to be couched primarily in terms of developmental constraints. If, on the other hand, almost any shape of wing can develop, then the actual shape, down to its finest details, may be explicable in selective terms.
Biologists differ about which of these pictures is nearer the truth. My own position is intermediate. Clearly, not all variations are equally likely for a given species. This fact was well understood by Darwin, and was familiar to me when I was an undergraduate under the term 'Vavilov's law of homologous variation' (Maynard Smith 1982:7).
Well, so much the more for mystery. A historical footnote to be remembered in an argument with Stephen Jay Gould. So I filed it in the back of my mind, since this kind of developmental constraint hypothesis has become more and more important in human evolution during the past few years. It turns out that the traits that differentiate some hominid species are in many cases the same traits that have the most variation within species.
Anyway, it was enough to get my interest when Peter Pringle's new book, The Murder of Nikolai Vavilov, showed up in the local bookstore.
When I flipped the book open, I found this description of Vavilov's desperate attempt to bring Dobzhansky back to the Soviet Union, from California where he had been working with Thomas Hunt Morgan:
Nikolai Ivanovich [Vavilov] began to show irritation at Dobzhansky's hesitation.
"Feodosy Georgievich, help us lift the country," one letter began. "This is a mission for all humanity. And start acting as a serious Soviet patriot. Truly the horizon here is wider and the future far more reliable than the comfort yet insecurity [of America]."
When Dobzhansky wondered how he would cope with Marxist ideology, with the new pushed-ups [Lysenko's men] and their insistence that dialectics be applied to science, Vavilov dismissed his concerns. "Dialectic methodology is nothing but a plus, it allows one to stay in touch with life's demands... Of course, you must horse-shoe yourself into dialectics. It's an easy business and will bring you nothing but usefulness. I am going to send you my dialectic masterpiece in a few days, 'Linnaean Species as a System.' Perhaps dialecticians will criticize me for it, but at least for me the dialectic approach was useful (Pringle 2008:164-165).
In the end, Dobzhansky refuses to return, and "No wonder!" you might well think. But the four-page passage really hooked me. How could this famous scientist have found himself in this position, accommodating such nonsense? The passage has a darker side: Vavilov succeeds in bringing another young geneticist back to Russia. Georgy Karpechenko returned to Vavilov's Institute only to be arrested and shot in the same purge that rounded up Vavilov himself.
Tragic vignettes like this ring throughout the book. Yelena Barulina, Vavilov's lover and companion, desperate to find where he is imprisoned, flees Leningrad ahead of the German advance -- and unknowingly takes up residence a mere fifteen minutes from the prison where Vavilov lay dying of starvation. Vavilov forced to defend Mendelism in a hopeless show trial staged to Lysenko's triumph. Vavilov's brother, Sergei, a prominent physicist in his own right, promoted to the presidency of the USSR Academy of Sciences while plaintively trying to rehabilitate Nikolai's reputation and find out the truth about his death. Perhaps most of all, the starving workers at Vavilov's Leningrad Institute during the German siege, saving the precious worldwide collection of seeds and potatoes, planting some varieties in the public squares.
Those details help to make the book a great story. But at the heart is a description of a truly visionary scientist. Vavilov was an innovator in genetics and plant breeding, but his advances came not only from careful experimentation but also from anthropology -- what we would today call an ethnohistorical approach.
Early in his career, Vavilov became convinced that domesticated crops could be improved by introducing genes from the wild progenitor species and very early domesticated strains. This strategy was one of systematic introgression, with an aim to bring in genetic variants that would allow earlier ripening in colder climates, resistance to disease and drought, and higher germination rates. This strategy has since been followed to great effect, even today -- I wrote about here in connection to wheat. Vavilov believed that the most ancient areas of domestication would still harbor strains of crop plants that had greater genetic variation, with greater adaptation to their local microclimates. In particular, he thought that hilly or mountainous areas around the zones of initial domestication would be places to find very ancient cold-tolerant, dry-tolerant, and disease resistant strains. By breeding these genes into the major food crops of the Russian plain, Vavilov hoped to radically improve Soviet agriculture, stave off droughts and end the need to import food from Western powers.
In all these things, Vavilov was entirely right. The modern conception of domestication and gene flow leads to almost exactly the same predictions. Moreover, Vavilov used historical and ethnographic observations to identify the early origins and dispersals of domesticates. He showed that the wheat in Ethiopia was not very diverse, casting doubt on its position as a primary center of domestication, while finding immense diversity in Central Asia and Afghanistan.
Here, in this high plateau, sparsely populated by subsistence farmers, Vavilov had confirmed his initial suspicion about their ancestors; that some of them had fled the plains where wheat and barley, lentils and rye had originally been cultivated by the earliest farmers and had chosen to live in these natural mountain fortresses where they were better protected from wild beasts and attacks from unfriendly neighbors. The Pamirs was not a "center of origin" for these plants, but it was a "natural laboratory" where over millennia "peculiar forms" of food crops had been developed (Pringle 2008:58).
To these, he would ultimately add maize diversity in Mexico, potatoes in Peru, and hemp across North Africa. And all the way, he collected seeds, always sending them back in great lots to Leningrad. By the time he had finished, he had amassed the greatest collection of domesticated seed diversity in the world, and had filled in the map of early centers of agriculture, documenting by crop diversity what archaeologists had yet to demonstrate by digging.
Pringle describes the many sources of resistance to Vavilov's ideas. Years before Lysenko rose to power, many of the USSR's plant breeders had very different priorities from Vavilov. They wanted to find ways to transform new, economically useful crops not already found in the USSR, such as rubber, cinchona, or even bananas. His fieldwork in Soviet Central Asia and Afghanistan was difficult, relatively unglamorous, and drew suspicion that he was a Soviet spy. But his later extended trips to America, Mexico, Africa, and southern Europe, were more comfortable and brought much more international attention to his work. Some were jealous of this acclaim -- particularly after his "Law of Homologous Series" earned him the Order of Lenin and fawning comparisons to the most famous Russian scientist, Mendeleev.
The Law itself derived from an important observation: related crop species, like wheat and rye, often had strains that had identical phenotypic variations -- awned and awnless, leaf shape, and stem size. These variations appeared to fall into a set series of categories -- a series that Vavilov compared to the periodic table of elements. Mendelian principles appeared to hold factors constant across species under different transformations. Today, we would indeed refer these similar variations to the topic of developmental constraints and shared genetic background.
The book describes the rise of Lysenko and its contribution to Vavilov's fall. The two were intertwined for years, as Lysenko rose from uneducated field assistant to the supreme position in Soviet agriculture.
Yet what surprised me the most was the way that Vavilov remained balanced on the knife's edge for so long, his ultimate fate looming on either side. His letters to Dobzhansky, read today, seem somehow out of character for a great scientist. But Vavilov was never a great scientist in his own mind; he always saw himself the humble servant of the state, forced to defend his science in the face of plain ignorance. He needed friends, and was protected from above for years until Stalin's will removed all defenders.
It is Pringle's great accomplishment to have described the inevitable fall with such precision and suspense. I was amazed that Vavilov lasted as long as he did, with the vast apparatus of the police state collecting evidence against him for ten years or more. Equal to the amazement is the sadness that such a great scientist, with so many important insights, was drawn down by constant troubles, the arrests of assistants and colleagues, and finally the opprobrium Stalin himself. And yet through it all, he managed to run his Institute, keep his seed collection growing, and build a network of agricultural field stations across the Soviet Union.
In the end, he was rehabilitated by Khrushchev, and later the records of Vavilov's interrogation and files were released. Pringle draws on these sources in chilling chapters describing how the great man was broken down, his closest colleagues shot, while others eagerly reported against him. There were moments when I turned away from the book in sadness, but truthfully, I couldn't put it down.
Maynard Smith J. 1982. Evolution and the theory of games. Cambridge University Press, Cambridge UK.
Pringle P. 2008. The murder of Nikolai Vavilov: The story of Stalin's persecution of one of the great scientists of the twentieth century. Simon and Schuster, New York.