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Book Review |
Department of Ecology and Evolutionary Biology, University of Connecticut, Storrs, Connecticut 06269-3043 USA
It is summer as I write this. This is the time when many cities have outdoor festivals, associated with the 4th of July in the USA, or other events, such as the "Viking Festivals" in the upper Midwest. Often there is food from the local merchants, sometimes proffered under something like "A Taste of ..." (Hartford—for us most recently). This book is a little like such an array of eateries: the whole range of choices is here, but no full meals are offered. I like these summer festivals (got to see Johnny Winter and eat Polish pierogis on the same night), and I like this book (a treat—plant evolution and domestication in one text). It is well written and it is certainly comprehensive. It is a textbook intended for advanced undergraduates and graduates in crop evolution courses, but in my view, could also serve as a first reference for students on a number of topics.
I assume the text was developed for the teaching that Dr. Hancock, a geneticist/evolutionist, does in his home department, Horticulture, at Michigan State University. The book is not encyclopedic, and for most topics, doesn't go into much depth, but it does cover a wide array of subjects from DNA technology to the origin of strawberries (one of Dr. Hancock's specialties). This is the second edition, and it continues in a market where there are not many competitors. The Beryl Simpson and Molly Ogorzaly text (2001)
is still the most widely used book for undergraduate courses in "plants and people" (although there are others too, like Levetin and McMahon, 2003
, this book has more of an orientation to first year students). With Charles Heiser's (1990)
and Herbert Baker's (1978)
readable textbooks out of print, Robert Schery's (1972)
and Albert Hill's (1952)
more encyclopedic texts long out of print, and Mike Balick's and Paul Cox's book (1997)
focused on ethnobotany, there are few options available for "plants and people" courses. The Bruce Smith (1995)
and Jack Harlan (1996) books are equally first-rate, but their topical coverage is of the origin(s) of agriculture, and the interface of plant and animal domesticates and archeology. That leaves the latest edition of Smartt and Simmonds (1995)
, and perhaps Jack Harlan's book on agriculture (1992)
, as the other choices in the niche the Hancock book occupies. The Smartt and Simmonds book, as an edited volume with contributions by experts on various crops, is more of a reference book, or a set of treatises for research consultation. While Harlan's text is the closest thing to a real competitor for Hancock's book, the orientation is quite different, with more focus on the development of agriculture in centers around the world—the conceptual area that Harlan (1992)
covers so expertly in textbook format. There is some treatment of crop evolution in Harlan, but it is quite a different flavor, exploring the big picture of crop changes and selection associated with the process of domestication.
Many colleges and universities have courses on "useful" plants, and it is gratifying that an increasing number of them are rediscovering the value of such courses. The political landscape, even internationally, makes it abundantly clear that creating an informed and scientifically empathetic electorate has to be among the most significant goals for educators and other botanists. In my experience, there is no better way to do that for plants, or maybe for biology as a whole, than through a course covering the species and processes upon which civilization, such as it is in the 21st century, depends (an unelaborated political comment). Teaching people about the origin of agriculture a brief 10 000 years ago and particularly about our primary cultigens (e.g., the "12 plants that stand between people and starvation"; Tippo and Stern, 1977
, pp. 284–285) is central to the effort to educate and build empathy. In addition, agriculture, domestication and domesticated organisms provide a compelling argument for protection of biodiversity, by offering a fundamental perspective to the consequences of extinction that Ed Wilson so eloquently distilled for species in general:
The worst thing that can happen ... is not energy depletion, economic collapse, limited nuclear war, or conquest by a totalitarian government.... The one process ... that will take millions of years to correct is the loss of genetic and species diversity by the destruction of natural habitats. This is the folly our descendants are least likely to forgive us. (originally in Harvard Magazine in 1980, but more accessible in Wilson, 1994
Of course, with the key cultigens, like rice, wheat, maize, and soy beans, the loss of a species or of even a substantial portion of the species due to disease spreading throughout the genetically identical populations of crops, would lead to mass starvation and world revolution. ‘Forgiveness’ in this context would be only a philosophical issue.
As indicated, Hancock's treatment is appropriate to the general subject of "plants and people." It would not be the book to choose for a first or second year course (that would be Simpson and Ogorzaly), but it fills the advanced undergraduate/graduate student niche. However, "PLANT EVOLUTION" stands out on the cover, with "The Origin of Crop Species" given second billing by virtue of font selection. This implies a different focus, and a much larger field of books and texts to choose from—all the many volumes on evolution. The author is even more direct about this implication in the Preface where he explicitly compares his treatment with other books on plant evolution. Most of us use economic botany or plants and civilization courses to teach a great deal of basic biology. Students learn about C4 pathways, plant anatomy, biogeography, and so forth, painlessly when they learn about the productivity of sugar cane, the roots of beets, or the distribution of cotton. In this book, a wide range of genetic and evolutionary topics are exemplified by crop origins and evolution, but that does not make this an evolution text, per se (see more below). Similarly, in the Preface the author suggests using the book in systematics courses. That is even more unlikely because the orientation is not at all appropriate for such courses. The overall tone is not taxonomic, and the principles of systematics are not treated at all (e.g., phylogenetics and cladistics) or only superficially (e.g., plant family classification). Books that one might expect to be cited, if the book is to be a serious taxonomic contender, include Cronquist (1988)
or the phylogenetically oriented Judd et al. (1999)
. They are not in the text or literature cited. In addition, systematics may be the arena in which most of the minor mistakes occur (again, see more below). This book treats a number of evolutionary topics, and many genetics topics, and it includes generally good taxonomy, but in the end, it is really a "crop evolution" text book. That is a significant contribution all by itself and the standard by which it will be assessed here.
The strengths of this book are many. As indicated, it is well written, with a special attribute being the succinct one-sentence to short-paragraph treatment of complicated phenomena and concepts. Generally, citations are abundant and appropriate (with some 55 pages of literature in the 313-page book). The style is easy going and even colloquial. The presentation of many topics indicates that Dr. Hancock must be a good teacher. In fact, his personal record supports that conclusion: he was recognized in 1999 by the American Horticultural Society with an "Outstanding Graduate Educator Award." Just about everything one can think of, from the origin of soup (well, at least cultivation and agriculture) to nuts (four chapters, about one third of the book, on the major domesticates), is included. But it is not the somewhat superficial treatment of the domesticates that makes this book unusual, it is the five chapters on genetics and evolution that set it apart from Smartt and Simmonds, Harlan, and other texts. Here, Hancock's ability to reduce complicated topics to their essence is showcased. This section also exemplifies the "taste of," or perhaps, more appropriately, a "Cliff's Notes" kind of style. The author covers material from courses in genetics, molecular genetics, cytogenetics and speciation in five chapters and 130 pages. Illustrations, mostly not original, but very well chosen for clarity, are regularly employed in this first section. The author has obviously gone to some length to select from the literature, including the classic literature, the most pedagogically useful presentations of techniques (e.g., electrophoresis), processes (e.g., the consequences of translocation heterozygotes) and concepts (e.g., "computer simulation of the influence of neighbourhood [sic] size on gene frequency variation"). There are no new syntheses in the text. The contribution, and a notable one at that, is in the combination of the processes inherent in the evolution of crops, and a treatment of the major domesticates—in one book. And, as the author points out in the Preface, this is one of the first volumes to combine the most recent molecular data and "conventionally acquired information." As an aside, I appreciate and applaud this creative phrase by Dr. Hancock. Like a "previously owned vehicle," this clever word selection avoids the pejorative implication that because the data one uses (for example, chromosome numbers and morphology) do not require white lab coats and gel rigs to gather, they are analogous to "used cars." Back to the original point: though current evolution texts do combine molecular with conventionally acquired information, that combination is not yet a common feature of texts on crop plant evolution. The combination of molecular and conventional data is well done in this book and, like the carefully selected and clear illustrations, is expeditious for teaching.
The second section on agriculture and the domesticates themselves leads with two general chapters, Chapter 6 on the origin of agriculture and Chapter 7 on the domestication process per se. The first chapter is, in my view, the weakest in the book. First, the majority of it seems irrelevant to the overall theme of crop evolution and the domesticates themselves. Hancock used two thirds of the chapter to cover the origin of the angiosperms, the emergence and evolution of Homo, and appearance of modern humans—interesting topics, but all taking place millions or hundreds of thousands of years before the issues treated in the book become relevant. Some of these interpretations are not only irrelevant, but also a bit out of date (e.g., patterns of human migration plotted from a 1971 reference). The last third of this chapter deals with what should be at least one whole chapter by itself—agricultural origins and the spread of crop plants. The material presented is well founded on the work of Harlan (1992)
and others, but there is too little of it for a text on crop origins. The chapter on the processes of domestication is good, with the set of topics slanted toward the author's particular interests. Thus there is more about genetic regulation of character expression, unusual and nice to have in a book like this, and less on the features by which domesticates differ from their wild ancestors, a set of topics that is essential in a text covering domestication.
The next four chapters (about 75 pages) treat individual crops placed in the usual categories—grains, legumes, starchy staples, and other crops. All the major crops are covered, with the orientation of the discussion belying the author's interests, and of course, the fact that this is a crop evolution text. The treatment of rice is a good example of topical coverage. The chromosome number, genome constituents and reproductive barriers are well described (in fact, an extensive table on genomes and chromosomes is presented), as are reproductive barriers, and the most likely wild progenitors are indicated. True to the plant breeding slant of the author, this is by far the best treatment, overall, I have seen of chromosome number, chromosome and genome morphology, compatibility and breeding barriers. It is good to see all of these covered together—as they are in no other text. However, this emphasis comes at the cost of other material. For example, there is: little or no discussion of the domestication process; no indication of the fact that this tropical crop, rice, is the only one among the major plant domesticates that withstands (flourishes in?) flooded conditions; no recognition that rice grows, perhaps not coincidently, where the majority of the world's population occurs, or that rice feeds almost half the world. The increasingly narrow genetic diversity of this keystone cultigen and the associated potentially devastating hazards attendant to that also are not recognized.
The treatment of the complicated and difficult story of the origin of maize is good. Similarly, that of the strawberry is very well done (not surprisingly!), but not overdone—except in the sense that a minor crop like this is included at all. But, of course, if I had written the book I would have included a long discussion of the domestication and evolution of the "pepino" (Solanum muricatum), that exemplar, that paragon of complicated, and perhaps multiple crop origins. Dr. Hancock, a specialist on the strawberry, is to be lauded for showing restraint in the description of this crop. The analysis of the origin and evolution of the capsicum peppers is fine, but also belies the academic history of the author (a masters degree student at Miami University—a former chile pepper research center), and overlooks some seminal references (e.g., the 1971 Barbara Pickersgill paper demonstrating that the wild forms of the Capsicum annuum peppers are ancestral forms, rather than weedy derivatives). There are some other idiosyncrasies. For example, peaches are given as much coverage as tomatoes, and the molecular work demonstrating that "tomatoes are really potatoes" (Spooner et al., 1993
), i.e., that Lycopersicon is firmly embedded phylogenetically within Solanum interjected among the tuberous and non-tuberous "potatoes," is not mentioned (this may be an artifact of Dr. Hancock's other academic history, a Ph.D. from the University of California-Davis, where tomato-genetics icon, Dr. Charles Rick, while accepting the phylogenetic work by Spooner et al. (1993)
, never liked the idea of treating tomatoes in the genus Solanum). But, the review I write, via that example, shows the bias of experience—the nightshades is the economic group I know best. Hancock is to be commended for not making research on the blueberry and strawberry the models for all the principles he discusses.
The strengths are also the weaknesses. Hancock covers so much in both major sections of the book that the depth on almost any topic is missing. Topics are clearly presented, but perhaps if this is a reader's first introduction to many of them, there is too little given. I asked a molecular evolutionist colleague in Spain, to look over the presentation of the molecular methods in Chapter 1 (e.g., a chapter covering AFLP, RAPD, RFLP, SSR). His comment was that the discussions were fine, but that it might have been better to cover fewer and do more with each. From my more naive perspective, I was glad to have the overall comprehensive treatment, including such things as a table comparing characteristics of the four molecular marker systems cited above. However, the attempt to be comprehensive and brief, including all those topics one might even mention in a lecture course on crop evolution, leads to odd detail (the origin and diversification of the angiosperms), and unnecessary explication (the origin and, radiation out of Africa of Homo sapiens).
Attendant to the style that makes the book easy to read, is a too-folksy use of "we" and "our" in such contexts as "next we shall describe" (though Hancock is the only author) and "our major crops" in many places throughout the book. This is good in a lecture, but is a less appropriate style for a textbook at this level.
There are a number of errors in fact and style, though none are fatal or particularly distracting. Following are some examples. In Fig. 6.1, "Arthropoids" are at the bottom of the Homo family tree. "Taxa" is often used where "species" is the appropriate term, plant families are inconsistently cited in the crops diversity section. The old and the new family names are randomly mixed (e.g., Asteraceae, Gramineae). Charles Heiser is cited as reporting heterostyly in capsicum peppers. More accurately, he just explains that among the generally self compatible capsicums, there are some that have long styles and are self incompatible—there is not reciprocal stylar heteromorphism (Heiser, 1995
). And, the dated diagram (from 1971) of human radiation cited earlier is included. Presumably British editing offers a certain flair, but it also introduces "Fibre" and "neighbourhood"—misspellings depending on the continent? But, the author himself has probably inserted "arrowed" in one of the figures, and, to my knowledge, coined "domesticant." The standard "cultivar" for cultivated varieties and "cultigen" for cultivated species would seem to suffice.
Overall, this looks like the translation of a comprehensive set of lecture material into a first-rate book. Dr. Hancock covers a great deal in the 250 pages of text. This is a festival of topics, featuring a taste of most of those relevant to crop evolution. There is much to chew on here, a great deal of food for thought. Most of the topics one can think of associated with crop evolution are here, but, most, except cytogenetic elements, are covered only briefly. I recommend the book for the audience intended as a first source on a number of topics, but, like many textbooks, it is not the ultimate resource. As I wrote above, this will also be a good first reference book for some. And I hope there are many courses and contexts that will find the topic, and this book, of use.
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FOOTNOTES |
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2 Gregory.Anderson{at}uconn.edu
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LITERATURE CITED |
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 TOP LITERATURE CITED |
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Balick M. J. P. A. Cox 1997 Plants, people and culture: the science of ethnobotany. Scientific American Library, New York, New York, USA
Cronquist A. 1988 The evolution and classification of flowering plants. New York Botanical Garden, Bronx, New York, USA
Harlan J. R. 1992 Crops and man, 2nd ed. American Society of Agronomy, Crop Science Society of America, Madison, Wisconsin, USA
Harlan J. R. 1995 The living fields: our agricultural heritage. Cambridge University Press, Cambridge, UK
Heiser C. B. 1990 Seed to civilization. Harvard University Press, Cambridge, Massachusetts, USA
Heiser C. B. 1995 Peppers. In J. Smartt and N. W. Simmonds [eds.], Evolution of crop plants, 2nd ed., 449–451. Longman Scientific and Technical, Harlow, UK
Hill A. F. 1952 Economic botany. McGraw-Hill, New York, New York, USA
Judd W. S. C. S. Campbell E. A. Kellogg P. F. Stevens 1999 Plant systematics: a phylogenetic approach. Sinauer, Sunderland, Massachusetts, USA
Levetin E. K. McMahon 2003 Plants and society, 3rd ed. McGraw-Hill, Dubuque, Iowa, USA
Pickersgill B. 1971 Relationships between weedy and cultivated forms in some species of chili peppers (genus Capsicum). Evolution 25: 683-691[CrossRef][ISI]
Schery R. W. 1972 Plants for man, 2nd ed. Prentice-Hall, Englewood Cliffs, New Jersey, USA
Simpson B. B. M. C. Ogorzaly 2001 Economic botany: plants of our world, 3rd ed. McGraw-Hill, New York, New York, USA
Smartt J. N. W. Simmonds 1995 Evolution of crop plants, 2nd ed. Longman Scientific and Technical, Harlow, UK
Smith B. D. 1995 The emergence of agriculture. Scientific American Library, New York, New York, USA
Spooner D. M. G. J. Anderson R. K. Jansen 1993 Chloroplast DNA evidence for the interrelationships of tomatoes, potatoes and pepinos. American Journal of Botany 80: 676-688[CrossRef][ISI]
Tippo O. W. L. Stern 1977 Humanistic botany. W. W. Norton and Co., New York, New York, USA
Wilson E. O. 1980 Resolutions for the 80s. Harvard Magazine, January– February: 22–26
Wilson E. O. 1994 Naturalist. Island Press, Washington, D.C., USA
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