Charles Darwin's work, including The Variation of Animals and Plants under Domestication, anticipated a wide range of modern evolutionary research. Darwin would indeed have been impressed with the scope of the eclectic set of papers in Darwin's Harvest: New Approaches to the Origins, Evolution, and Conservation of Crops (even though he might have had some trouble grasping the details, as he lacked an understanding of Mendel's crosses and statistics). However, Nikolai Vavilov's work has had a more direct connection to this volume, and it would be more properly called “Vavilov's Harvest,” even though his name is more obscure and less marketable.
As recounted in Timothy Motley's opening chapter, Vavilov, who worked from 1921 to 1940 in Leningrad, laid many of the foundations of crop plant research. Among other findings, he documented the close relationship in origins between crops and some weeds (oats and rye were once weeds infesting barley and wheat, as Vavilov noted by 1926). Vavilov also developed detailed hypotheses about the biogeographic centers of crop origins. He proposed eight of these centers, although it is now argued that there are at least a couple more, as shown in this volume.
Perhaps most important, Vavilov believed that the improvement of agriculture was best achieved through the collection of thousands of crop varieties, and through their use in careful selective breeding to develop better varieties. Indeed, Vavilov pursued germplasm collections with great vigor in the 1920s. It was the selective breeding that caused him to run afoul of Trofim Lysenko, who believed (for example) that repeated exposure of wheat seeds to cold would generate cold-adapted progeny. With the support of Stalin, Lysenko replaced Vavilov as president of the Bureau of Applied Biology (now the Vavilov Institute of Plant Industry). Vavilov was later arrested on charges of espionage, and tragically died in prison in 1943.
In this volume, 36 authors contributed to 15 chapters, grouped around topics that probably would have pleased Vavilov: “Genetics and Origin of Crops: Evolution and Domestication,” “Systematics and the Origin of Crops: Phylogenetic and Biogeographic Relationships,” “The Descent of Man: Human History and Crop Evolution,”and “Variation of Plants under Selection: Agrodiversity and Germplasm Conservation.”
There are many interesting stories and insights among these chapters. The collection certainly achieves its goal of providing a broad sample of current research on a diverse group of crop plants. Still, it was never clear to me why these particular authors and chapter topics were chosen. Were these the most recently advanced or instructive cases? Why not pineapples, cocoa, or bananas? Some of the crops are of obvious importance, including wheat, corn, beans, cassava, potato, and sugarcane, but others are plants that many of us have hardly heard about and never tasted, like chayote (a cucurbit widely grown in Latin America), oca (an Oxalis species grown for tubers in the Andes), and breadfruit. Common themes of the chapters included the use of DNA markers and the importance (and poor funding) of germplasm resources.
The editors' own research interests seem (not surprisingly) to have influenced some of the choices of topics. At the time the book was being written, Timothy J. Motley was associate professor in the Collum Program for Molecular Systematics at the New York Botanical Garden; he has since become the J. Robert Stiffler Distinguished Professor of Botany in the Department of Biological Sciences at Old Dominion University. Motley's research has focused on plant evolution and phylogeography in Pacific islands, particularly of plants in the family that includes coffee. Nyree Zerega and Hugh Cross are Motley's former students, with interests that include the origins (and present diversity) of breadfruit and chayote, respectively. Zerega is the director of the Plant Biology and Conservation Program at Northwestern University and the Chicago Botanic Garden. At the time of publication, Cross was a postdoctoral researcher at the National Herbarium of the Netherlands, Leiden University.
Unfortunately, as is so often the case with edited volumes, the chapters are uneven in content. Some are written as reviews that are broadly accessible to a wide audience, but others are much more like technical journal articles, complete with materials and methods, and are probably of greatest interest only to specialists. Some, such as the chapter on walnuts, seem to be mostly about phylogeny, with little real emphasis on crops (the harvest side of the title). Two appendices help to explain the biochemical and statistical techniques and terms used. The index is adequate, but could probably have usefully referenced more of the authors and details cited in the chapters.
The references cited are handily included with each chapter. It appears that most of the literature reviews were completed in 2004. I was therefore surprised that Norman Ellstrand's highly relevant 2003 book Dangerous Liaisons? When Cultivated Plants Mate with Their Wild Relatives was apparently not cited, especially for discussions on gene flow between modern crops and their relatives, although Ellstrand and colleagues' 1999 review article was noted. The book is generally free of formatting errors.
My favorite chapter was that of Edward S. Buckler IV and Natalie Stevens on the origins, domestication, and selection of maize. Maize is not only one of the world's most important crops but one whose evolution has long been among the most complicated and controversial—and arguably the most remarkable crop-breeding accomplishment of all time. Buckler and Stevens piece together not only the fascinating story of how corn was selected from teosinte by Native Americans over several thousand years but also the history of scientific research that revealed this pathway. The difference between teosinte, with only 6 to 12 kernels in two interleaved rows, and domesticated corn, with cobs bearing more than 20 rows of kernels, is apparently due mainly to just five regions of the maize genome, most probably started from a single domestication event in the Balsas River Valley of southern Mexico. This story is also a vindication for George Beadle and his persistence in supporting his teosinte hypothesis from 1939 to his death in 1989, only mildly distracted by a Nobel Prize in biochemical genetics and the presidency of the University of Chicago.
I was also fascinated by chapters on the evolution of the common bean and the uses of landraces of wheat to investigate the origins of European agriculture. Further, the book highlights a number of interesting conundrums in the evolution of crops, such as the origins of sweet potatoes in the Pacific and the development of sugarcane.
As broad as this book is, it could best serve as a prelude to a deeper discussion of how we can link fundamental studies of crop evolution, systematics, phylogenies, and biogeography more vigorously to crop improvement. Borrowing from the book's title, what are the detailed implications of the origins and evolution of crops to their harvest? A few of these chapters showed a path forward: Buckler and Stevens in discussing starch pathways in corn, Roberto Papa and colleagues in reviewing work (largely by Paul Gepts) that shows two independent domestications of beans and the implications for disease resistance, and Barbara Schaal and her colleagues in describing carbohydrate and beta-carotene variants in cassava (a critical crop in Africa, where average yields are only 8 metric tons per hectare, compared with a potential of 80!). A thoroughly modern synthesis of evolution into crop breeding would be a book that both Darwin and Vavilov could enjoy.
