The Anti-Monoculture Mania

By Thomas R. DeGregori

The critics of modern life never cease to amaze us. Everyday there is a new crisis of modernity that threatens our continued existence. Nowhere is this more evident than in agriculture. We're told that the use of pesticides is generating soaring cancer rates, yet there is nothing in the statistics which confirms this alarmist rhetoric. It is claimed that the Green Revolution led to a decline in vegetable production. Never mind that in most areas where there were significant advances in the production of modern grain varieties, there were also the largest increases in non-grain consumption; and that the world's population is eating a more diverse diet than ever before. And also, never mind that without the yield increases in Green Revolution grains, there simply would not be any land left for other crops (or for wildlife and habitat conservation), as farmers would plant every bit of land available with the crops that produced the highest yield of calories per unit of land.

Critics resort to unbounded imagination when the facts of the Green Revolution don't support their case: they now claim that increased production is achieved at the expense of the nutritional value of the crop we consumed in the past. One activist, Alex Wijeratna of ActionAid, generalizes the nutritional attack against the Green Revolution by claiming that: "Two billion people now have diets less diverse than 30 years ago. The Green Revolution stripped out the micro nutrients and encouraged monocropping" (Wrong 2000). Where he gets his evidence for this assertion is not mentioned, which is appropriate since there isn't any. The number of people deemed to be in hunger (i.e. as having less than adequate nutrition) as measured by every reputable international agency has been falling steadily over the last decades, even as the world population is increasing. Despite this, somehow there has been an otherwise undetected two billion increase in the number suffering from malnutrition - that is to say, not detected by those who lack an anti-technology agenda that they wish to promote. How then do we explain the fact that in the areas in which the Green Revolution technologies have most effectively taken hold, there have been spectacular decreases in infant mortality, and increases in life expectancies and disability adjusted lifeyears (DALYs), resulting from a variety of factors including improved nutrition.

Anyone who has traveled in Asia over the last decades cannot have failed to notice the increases in height not only across generations but often within them. When one observes as I have, a consistent pattern where younger children are taller than their older siblings, it indicates that there was a significant improvement in the family diet between the birth of the two children which led to the increased height of the younger child. (A note of clarification: taller does not necessarily mean healthier within a group, particularly when conditions of nutrition and illness are comparable. Taller is very definitely an indicator of nutrition and overall health when it is a measure of the change in the average height of a group through time.) Nowhere has this been more evident than in China. The particularly dramatic increase in height in the population of China over the decade and a half following the Deng Xiaoping-led reforms is documented in an article titled - "Richer and Taller: Stature and Living Standards in China, 1979-1995" (Morgan 2000). The introduction of the "responsibility" system in agriculture in China in the late 1970s led to China's becoming the world's leading wheat producer by the early 1980s. It quickly yielded this position as farmers found it more profitable to turn to vegetable and other production to satisfy the increased demands of an economically better-off population and of international trade. China could do this because it could meet its wheat needs by importing from areas of monoculture production.

The dangers of monoculture?

The "dangers" of monoculture prompted a Newsweek cover story (June 9, 2003). Once again we are told that there is a crisis in agriculture because crop monocultures are failing to prevent pests and disease. The irony of this claim is that just when much of the world has seen the elimination of the devastating famines from crop losses that were once the scourge of humankind, the shrill cry against the agricultural system that has made this possible grows ever louder. That only Africa, which was tragically passed over by the Green Revolution, has experienced near total crop losses is truly the exception that proves the rule of the benefits that modern agronomy brings to crop stability. Polycultures in African agriculture have not prevented the periodic outbreak of famine. Needless to say, the products of monocultures are what provide the famine relief.

Apparently the lead reporter on the Newsweek story, Matt Margolis, does not find it strange that critics continually hark back to the southern corn-leaf blight in the U.S. in 1970, since they cannot come up with any comparable loss in the last half century in corn or wheat or rice, the staples which provide about two-thirds of the world's food production. The $1 billion in losses, amounting to about 15 to 25% of the crop, was substantial, but these loses should be considered against the fact that corn yields had more than doubled over the previous two decades, and that the crop year following the blight was one of record yields. When not citing the corn blight, the critics go back more than 150 years to the Irish potato famine.

Monoculture and "nature"

There remain those who consider monoculture to be unnatural, as if anything involving agriculture could be totally unnatural or anything involving humans could be totally natural (whatever that may mean). Ironically, it can be argued that humans developed agriculture in what could well be considered an era of "monocultures." In the transition from the Pleistocene to the Holocene, "climatic changes in seasonal regimes decreased diversity, increased zonation of plant communities, and caused a shift in net antiherbivory defense strategies" (Guthrie 1984, 260). The ecological richness of late Pleistocene in many of the areas where humans were first to develop agriculture, gave way to "relative ecological homogeneity during the succeeding Holocene" (Guilday 1984, 251).

The warming climate meant that areas in many latitudes began once again to experience spring thaws and run-off, which frequently caused erosion. These areas were often colonized by single strands of hardy weeds with nutrient rich seeds whose botanical weediness required aerated soils which the erosion created. The fact that there were monodominant stands of these grasses meant that humans could form small clusters of relatively permanent habitation as they regularly harvested nature's monoculture seed crop. In many respects, this close association with the plant precursors to wheat meant that humans were domesticating the crop even before agriculture, as the periodic harvesting of the seeds gave an evolutionary advantage to those seeds that adhered most closely to the stalk. It allowed for the development of a variety of technologies for harvesting and utilizing the crop. And it gave so many points of observation of the plant cycle that by the time agriculture became necessary, humans already possessed its basic instruments and knowledge.

Nobody is going to start the laborious process of cropping a plant if it is freely available in the environment, so it is likely that humans had the ability to engage in agriculture before they took the trouble to engage in it. The intensive harvesting of the monodominant crop led to population increase, and eventually some of the population had to move into other areas. They took their "domesticated" seeds, their technology and their knowledge with them. The early agricultural staples originated as monodominant strands in harsh or marginal conditions. Storing energy underground in tubers or producing energy rich seeds for wide dispersal are competitive survival mechanisms for plants in marginal growing conditions, and became a source of food for humans. One would hesitate to go so far as to argue that agriculture would not have occurred had it not been for nature's monoculture, but it would seem that it was clearly a major contributing factor.

Moving "domesticated crops" out of their harsh original environments into ones with richer, wetter soils allowed them to thrive. In time, civilization emerged, but agriculture needed considerable investment in labor, and it required the crops to be protected because they had been moved into environments replete with competitors. The necessity for crop protection emerged with agriculture not because of any practice of monoculture but because crops were now being grown in areas outside where they originated. And contrary to "organic" agriculture mythology, crops have had to be protected ever since agriculture got started, frequently with very highly toxic "all-natural" compounds such as various forms of arsenic.

Ecological stability and lack of diversity

Plant breeding, synthetic fertilizers and irrigation are a part of the complex of agronomy that has allowed humans to bring agriculture back into harsh agroclimatic spheres which were dominated by a very narrow array of vegetation. The agriculture of the high plains of western North America typifies the monoculture that critics deem to be in "crisis." But rather than replacing diverse agricultural or diverse natural systems, modern agriculture on the High or Great Plains has probably added to the diversity.

It would be hard to imagine an area less diverse than the Great Plains during the Holocene. If one had taken a journey of several thousand miles, from the Great Plains in the heart of what is now West Texas north into modern Canada, for half that distance one could have walked every step of the way (except to cross rivers and creeks), on just two different species of Great Plains short grass, and then the rest of the way into the Prairie Province of Canada on two other varieties of short grass (Bailey 1976 and Küchler 1966). Even today, "productive grasslands are usually lower in plant diversity than less fertile ones" (Moore 2003, see also Grime 2001). This was a condition that lasted for more than ten thousand years, until the arrival of the settlers with European agriculture. It replaced a very rich and diverse ecosystem that crashed with the climatic change of the late Pleistocene. Diverse ecosystems are no more or less a protection against population crashes brought about by major climatic changes than are mono or duodominant systems.

As the ecological mosaic shifted "from plaids to stripes," creating zones of greatly reduced plant species diversity, the animal life that the habitat supported was similarly transformed. "As the plant communities became more zoned, there were fewer optimal 'plaid' mixtures of plants for the species requiring nutritional diversity in their diet" (Guthrie 1984, 282). This opened a niche for the dominance of "large ruminants such as bison" which can "flourish on a monotonous summer range of just a few plant species" because of the ability of their "rumen to synthesize a balanced diet of amino acids, fatty acids and vitamins" (Guthrie 1984, 277). In addition, the bison ranged from the Eastern Woodlands, where they could be found in small numbers in clearings, to more mountainous areas west of the Great Plains. As a consequence, they would have come in contact with a vast array of other animals at the periphery of their habitat, which conceivably could have transferred a disease contagion to the great herds of the plains. That this ecosystem lasted ten thousand years would indicate that diversity is but one of many factors of sustainability in natural and in human created ecosystems.

While the short grass of the Great Plains was creating an ecological niche for a ruminant like the Bison, the taller grasses of Eurasia allowed for more diverse animal life including horses and humans. "Grass seeds which tend to be destroyed in the rumen composting process are usually isolated high on the undigestible coarse stems of mature plants. This coarse stem is avoided by most ruminants because it clogs the rumen with relatively undigestible fiber." Horses feed on the grass seeds while the coarse stem passes "quickly through the gastrointestinal tract in essentially undigested form. At the same time, horses can ingest, masticate, and digest the seeds which are high in nutrient quality and easily assimilated" (Guthrie 1984, 285).

In contrast to the gorilla with a large hind gut which can hold and extract what little nutrient fibrous vegetable matter has, humans, like horses, pass the fiber quickly, utilizing very little of its nutrient. Thus today a diet high in fiber (relative to our current diets) facilitates moving food more quickly through the intestines with a variety of benefits including absorption of fewer plant toxins. However, such a digestive system, combined with an energy demanding brain, requires a nutritionally energetically-dense diet of which grass seeds were to become a major component (DeGregori 2001, 77-81). The poor in the world today may get the benefits of a high fiber diet, but unfortunately this is more than offset by being nutritionally deficient. "Hunger" is not necessarily a function of a quantitative lack of food but of its qualitative deficiencies. In fact, the poor may well be eating more and passing larger quantities of it as waste than those on richer diets. According to Feachem, the daily per capita production of human waste is about 100 to 200 grams of solid waste in developed countries compared 130 to 520 grams in developing countries (Feachem 1983, 4).

Monoculture: the cause of crop losses?

It is interesting to note that the 1970s corn blight resulted from an attempt to introduce an element of diversity to the corn plant. In the corn blight case, "susceptibility to blight is conditioned by the mitochondrial genome" (Parrott).

Maize with one genotype of mitochondria, called T cytoplasm (Texas male sterile), turned out to be susceptible to the blight fungus. Prior to the introduction of the T cytoplasm, all the maize had N (normal) cytoplasm. In this case, switching from one cytoplasm genotype grown throughout the country to two cytoplasm genotypes is what allowed the disease to develop: increased cytoplasmic diversity allowed disease to develop (Parrot 2003).

Wayne Parrott adds: "Needless to say, we are back to the one cytoplasm which has been stable for centuries." From the first work on wheat in Mexico, it was clear that the yield increases of the Green Revolution depended both on increases in plant production and on decreases in crop losses. Since then, some of the most important and widely planted high-yielding varieties (HYVs) were bred from a multiplicity of varieties from different countries, creating varieties that were multiple-disease resistant, and that were also better able to withstand other forms of stress.

While attempting to build more resistance into maize actually made it more susceptible to corn blight, many of the wheat and rice varieties of the Green Revolution have successfully built in multiple resistances for a variety of forms of stress including disease (Rosegrant and Hazell 2000, 311-312). For both wheat and rice "components of genetic diversity other than spatial diversity have improved over time." This includes:

"temporal diversity (average age and rate of replacement of cultivars); polygenic diversity (the pyramiding of multiple genes for resistance to provide longer lasting protection from pathogens); and pedigree complexity (the number landraces, pureline selections, and mutants that are ancestors of a released variety)" (Rosegrant and Hazell 2000, 311-312).

The argument that the Green Revolution crops have led to a diminution of genetic diversity, with a potential for a disease or pest infestation engendering a global crop loss catastrophe, is taken as axiomatic in many circles as one more threat that modern science imposes upon us. In fact, there is a sizeable and growing body of solidly based, scientific, peer-reviewed research that finds the exact opposite of the conventional wisdom (CIMMYT 1996, Evenson and Gollin 1994 & 1997, Gollin and Smale 1998, Rice et al. 1998, Smale 1997 & 1998, Smale et al. 1996 & 2002 and Wood and Lenné, 1999). Findings for wheat for example, "suggest that yield stability, resistance to rusts, pedigree complexity, and the number of modern cultivars in farmers' fields have all increased since the early years of the Green Revolution" (Smale and McBride 1996).

The conclusion that the "trends in genetic diversity of cereal crops are mainly positive" is warranted by the evidence. Moreover, this diversity does more than "just protect against large downside risk for yields." It was "generated primarily as a byproduct to breeding for yield and quality improvement and provides a pool of genetic resources for future yield growth." Consequently, the "threat of unforeseen, widespread, and catastrophic yield declines striking as the result of a narrow genetic base must be gauged against this reality" (Rosegrant and Hazell 2000, 312).

Most critics do not seem to realize that the Green Revolution was not a one-shot endeavor for wheat and rice, but an ongoing process of research for new varieties and improved agricultural practices. There is an international network of growers, extension agents, local, regional, national and international research stations, often linked by satellite, that has successfully responded to disease outbreaks which in earlier times could well have resulted in a global crisis. Historically, the farmer had access to only a limited number of local varieties of seeds. Today, should there be a disease or other cropping problem, the farmer can be the beneficiary of a new variety drawn from seed bank accessions that number into the hundreds of thousands for major crops like rice. With transgenic technology, the options for the cultivators are becoming vastly greater. Monoculture today is in fact not only consistent with an incredible diversity of means for crop protection, it is the sine qua non for them, because it is not possible to have such resources for all the less widely planted crops.

In a world of 6 billion people, with over 2 billion of them in agriculture, it is not difficult to cherry-pick instances of major crop disease outbreaks, but the issue is how representative are these examples, and what should our response to them be? Too often, narratives such as that in Newsweek are used to condemn the Green Revolution, which has increased food production by 2.7 times on about the same land under cultivation, accommodating a doubling of the population over the last 40 years, while creating more stable food production in areas that have been historically most prone to crop failures and famine.

Monoculture and crop protection

Even protected plants produce some chemical defenses, though fewer than the same plant unprotected. Those plants that have survived in nature have done so because of the successful chemical and other defenses they have evolved. Domesticated plants that have long been removed from the habitat of their origin and the predators therein, often lose the ability to produce specific chemical and other defenses, since the defenses would not have any survival value and would likely be wasteful of energy. This explains why farmers and plant breeders seek plants from the original habitat for crossbreeding for resistance, when a new disease or predator invades their domain. Given this process of developing resistance, followed by new forms of attack, followed by new resistance and new means of attack, in a seemingly never-ending process, it is understandable that with human intervention in the form of domestication, there is the same process of chemical or biological defense against insects and micro-organisms, followed by the evolution of means of overcoming these defenses in an ongoing process. Critics of modern agronomy, in recognizing this process, offer a perverse form of Luddite logic in concluding that no defense should ever have been tried since the insects or micro-organisms would eventually evolve means of overcoming them. How we would be better off by never having tried to protect the crop is never fully explained.

Contrary to the doomsayers, some of the modern commercial plant varieties which have had resistance genes bred into them have maintained this resistance for long periods of time - up to 50 years in some cases - and are still functioning well.

"In the United States, the T gene in barley has held up against stem rust for over 50 years; similarly, in wheat the Hope gene has kept stem rust in check for over 40 years and the LR34 gene has limited leaf rust for more than 20 years" (Sanders 2001).

To Sanders, "multiple-gene resistance and other techniques are preferable when they are available" but we "use what we have if it works, and we anticipate breakdowns" (Sanders 2001). Not only is this pragmatic process of breeding-in plant protection vital for agriculture; there is no alternative to using a variety of modern crop protection strategies.

Biotechnology, monoculture and crop protection

Modern biotechnology has given us new means of crop protection. As would be expected, some of the earliest work has been done on the most widely grown crops such as corn or soybeans which are often grown as monocultures. The most famous and controversial is the splicing of a gene from the bacterium, Bacillus thuringiensis (Bt) into corn to produce a plant resistant to the corn borer. When two research reports and a News of the Week article on the development of resistance to the Bt toxin were posted online in Science (August 2001), anti-biotechnology groups almost instantly picked on the recognition of Bt resistance and were online with it in their campaign against genetically modified food before most subscribers even had the hard copy in hand. The online postings were quickly followed by news stories strikingly similar to the anti-GM postings. A close examination of the articles (or even a cursory one) would have indicated that an understanding of them would not advance the cause of those against the use of biotechnology in agriculture.

First, the Bt "resistant strains of at least 11 insect species have been documented in the laboratory" while only "Bt resistant variants of the diamondback moth have been identified in the field" (Griffitts et al. 2001). Checking the article footnotes for resistant strains found in the field indicates that they occurred before 1994, the date of the cited article, which was also before the first Bt modified varieties were released (Griffitts et al. 2001). In fact, resistance to live Bt spray by the Diamondback moths emerged in the field as early as 1989 (Palumbi 2001). "Some populations of diamondback moths, a devastating pest of cabbage and related crops, are no longer bothered by sprays of Bt bacteria used by organic farmers" (Stokstad 2001). In other words, the use of the live Bacillus has the same potential of creating resistant strains as does the use of the toxin engineered into the plant, though obviously more extensive use of the Bt toxin in any form will likely accelerate the development of this resistance. But note again, the only resistant strains that were actually found in fields, were found in those involving "organic" agriculture.

Those in the environmental movement who oppose the patenting of life forms somehow believe that "organic" farmers have an exclusive absolute property right to use and prevent others from using not only the live Bacillus but also the protein toxin that it produces. The three articles in Science reveal a critical difference between the use of science in agriculture and those who would favor some other method. Modern agronomy, monoculture or otherwise, provides a variety of strategies for agriculturalists to employ, in addition to Bt, such as chemical pesticides and refuges to maintain a population of insects that do not develop a resistance to the Bt toxin. The articles demonstrate that modern biotechnology provides the ability to identify and monitor "resistance allele frequencies in field populations," so that farmers will have a "direct test of whether the highdose/refuge strategy is succeeding." This "may allow enough time for the strategy to be adjusted to reverse the increase" if the existing strategy "starts to fail" (Gahan et al. 2001, see also Ferre and Van Rie, 2002). The articles indicated that insects were evolving defensive mechanisms which presented a challenge to create new strategies to combat them.

Those who read the online environmentalist postings would never have surmised that the authors of one of the articles were defining ways of facilitating the long-term use and expected benefits of Bt engineered crops. This is clear in the following concluding reference to "the opportunity to make informed modifications to a strategy that could sustain the use of Bt transgenics and prolong their environmental benefits of reducing dependency on conventional insecticides" (Gahan et al. 2001). Once again note that thus far, the greatest success in bioengineered crops has been in those identified as monoculture, though other crops have also been engineered and in time many other crops will be improved by this technology.

Those who oppose all uses of biotechnology in agriculture, deeming it to be inherently evil, lack any realistic options to counter the growth of resistance to live Bt spray. Biotechnology and agronomy, like all scientific inquiry, are processes of inquiry (the scientific method) and problem solving. They are in search of best solutions to problems, not ultimate solutions. In some cases, such as that of live Bt spray and the T gene in Barley, the solution works for a long time. In others, the time frame is much shorter. The critical difference between science and the presumed alternatives is that science has a way of moving forward to find solutions and even to anticipate a need for them (Mokyr 2002, 38). From the way that the opponents of Bt corn have been characterizing its threat to "organic" farmers, one might surmise that the "organic" farmers could continue using live Bt spray in perpetuity were it not for the intrusion of the bioengineered Bt serpent into their Edenic preserve.

Specialization in nature, like other forms of specialization, limits the options of the organism but gives it an advantage in exploiting the environment to which it has adapted. A plant or insect subject to attack by a specific insect or parasite will tend to develop resistance to it. In the "struggle for survival" in nature, the emergence of a trait that improves the ability to resist predation or to prey on others, will spread through the species, becoming dominant.

Biotechnology and monoculture: future possibilities

Plant biotechnology is not simply a luxury but increasingly a necessity. Once again, the crops that are rightly drawing the most attention are those like rice which are widely cultivated, often in a regimen defined as monoculture. Though rice yields have tripled over the last 30 years, we are now "fast approaching a theoretical limit set by the crop's efficiency in harvesting sunlight and using its energy to make carbohydrates" (Surridge 2002, 576). According to John Sheehy, plant ecologist at IRRI, "the only way to increase yields and reduce the use of nitrogen fertilizers is to increase photosynthetic efficiency" (quoted in Surridge 2002, 577). Plant evolution has shown us an improved pathway for photosynthesis.

On at least 30 separate occasions, different plant lineages have evolved to use the Sun's energy more efficiently, making sugars in a two stage process known as C4 photosynthesis (Surridge 2002, 578).

Surridge adds:

About 10 million years ago, falling concentrations of carbon dioxide in the atmosphere gave plants using C4 photosynthesis an important selective advantage. The ancestors of maize were among these plants (Surridge 2002, 578).

Conventional C3 photosynthesis is used by rice, wheat and most other cereals. Simply stated, the work to transform stable C3 crops to C4 is going ahead with a major monoculture crop, as this is a crop which feeds billions of people and whose improvement will feed hundreds of millions more. The need in agricultural plant breeding is for a variety of different types of research technologies, including biotechnology as well as the technologies of longer standing which have brought us to where we are today (Powell 2002 and Terada et al. 2002). The sequencing of the genome of two varieties of rice will be an important new tool in creating rice varieties with genes that express the C4 enzyme (Ronald and Leung 2002, Goff et al. 2002 and Yu et al. 2002). It is also likely to provide valuable insights for work on wheat, maize and other grains which, along with rice, provide two-thirds of the world's calories (Cantrel and Reeves 2002, and Serageldin 2002). Biotechnology engineering in iron-rich rice is likely to be an important factor in fighting iron deficiency anemia which affects about 30% of the world's population, mostly women, and is the most important nutritional deficiency (Lucca et al. 2002).

Improving the photosynthetic efficiency of rice has the potential both of increasing its nutritional value and enhancing its ability to withstand environmental stress. The harnessing of solar

energy by photosynthesis depends on a safety valve that effectively eliminates hazardous excess energy and prevents oxidative damage to the plant cells. Many of the compounds that protect plant cells also protect human cells. Improving plant resistance to stress may thus have the beneficial side effect of also improving the nutritional quality of plants in the human diet. The pathways that synthesize these compounds are becoming amenable to genetic manipulation, which may yield benefits as widespread as improved plant stress tolerance and improved human physical and mental health (Demmig-Adams and Adams 2002).

Demmig-Adams and Adams add that things like vitamins,

antioxidants, and phytochemicals are not mutually exclusive. Major groups of phytochemicals (produced by photosynthetic organisms) include isoprenoids, phenolic compounds, sulfur compounds, and essential fatty acids. ... Enhancing the photosynthesizers' own protective systems may also improve the nutritional quality of foods, because fundamental cellular signaling processes and protective mechanisms are highly conserved (Demmig-Adams and Adams 2002).

Photosynthesis involves "collection of solar energy and its efficient conversion into chemical energy," a process susceptible "to damage by any excess solar energy." Because of the "parallel functions of antioxidants in plants and humans, new mechanistic hypotheses should incorporate information from both plant physiology and human physiology" (Demmig-Adams and Adams 2002).

Protecting photosynthesis in the face of environmental stress as well as protecting human health against environmental or pathological stress requires improved understanding of molecular functions and the intersection between stress, disease, and physiology for both plants and humans (Demmig-Adams and Adams 2002).

Informed, intelligent criticism is essential to keep agricultural research operating to the benefit all of humankind. Opposition based on clever slogans and misinformation can drown out the voices of those with legitimate concerns, who might be hesitant to speak out, for fear of being identified with those whose knowledge and agenda is suspect. Critics of modern agronomy - biotechnology and monoculture - would gain greater credibility if they were better informed and could demonstrate substantial experience in helping to feed people.

To critique or not to critique

One would not wish to stifle criticism by demanding that every critic provide a responsible alternative before voicing concerns. This is particularly true when the criticism is intended to be constructive, seeking to bring improvement to an ongoing process. But when the criticism reaches the level of that against modern agriculture and the critics are actively seeking radical if not complete transformation of it, then we have the right if not the duty to demand that they state how they propose that we feed the world's population. If they speak about diversifying the crop production, we have a right to ask what crops they going to take out of production to free up the land for greater diversity of production, and who will supply the added labor for a more complex system.

This last question is vitally important for those opposed to Vitamin A enhanced rice who blandly state the need for greater crop diversity. Fine! Very fine in fact! Who is opposed to the families of poor subsistence rice farmers eating more mangoes and fruits and vegetables of various kinds, and even some meat or fish? Do the critics really believe that the poor families need their activist saviors to tell them that such dietary diversity would be nutritionally beneficial as well as desirable in every other way? If the critics have ways of bringing about this changed pattern of cropping, why don't they simply do it, and stop wasting their time attacking a system that by their reckoning is a failure? If there are ways of doing agriculture that require fewer inputs but provide the same if not greater yields per unit of land, then why are they not out there showing the farmers how to do it? Farmers the world over may be on the conservative side, but in the modern era they have been one of the most world's responsive groups when it comes to producing a better crop.

It is one thing for critics to state a utopian alternative without ever having to show how it works. It is another thing to be out in the field where new problems regularly arise and new solutions have to be found. What counts is raising crops and feeding people and trying through time to do a better job of both. From the earliest agricultural systems to the present, protecting the crop has always been a central issue of agriculture, and never have farmers been more successful at it than at the present time.

For the defense of modern agricultural ecosystems, Wayne Parrot has the right "take-home message."

[B]uilt-in disease resistance is the most reliable and economical method to achieve stable crop yields, be it under monoculture or polyculture conditions. These resistances can be bred in from wild relatives or obtained via recombinant DNA technology (Parrott 2003).

Parrot wisely adds:

Ultimately though, evolution is a dynamic process, so the job of resistance is never done. We may achieve disease protection which will last anywhere from a few years to several centuries, but ultimately, I would not consider anything as permanent (Parrott 2003).

Thomas R. DeGregori is a Professor of Economics at the University of Houston and the author of the forthcoming book, Origins of the Organic Agriculture Debate Iowa State Press: A Blackwell Publishing Company -http://store.yahoo.com/isupress/0813805139.html - which formed the basis of much of the material in this paper.

*I am indebted to my colleague in Anthropology, Randolph Widmer for his valuable assistance for the sections on domestications and the conditions that preceded it.

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