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Date:

May 11, 2001

Subject:

The GM Crop Debate in the Context of Agricultural Evolution

 

AgBioView - http://www.agbioworld.org

The Genetically Modified Crop Debate in the Context of Agricultural
Evolution

- Channapatna S.Prakash

Plant Physiol. (EDITOR'S CHOICE) 2001 126: 8-15

HTML version with hyperlinks and photss at
http://www.plantphysiol.org/cgi/content/full/126/1/8
Reprint Version with photos at
http://www.plantphysiol.org/cgi/reprint/126/1/8

Introduction

"Whoever could make two ears of corn, or two blades of grass grow upon a
spot of ground where only one grew before would deserve better of Mankind,
and do more essential service to his country, than the whole race of
politicians put together."
- The King of Brobdingnag, Gulliver's Travels by Jonathan Swift, 1727.

"I believe that we have now reached a moral and ethical watershed beyond
which we venture into realms that belong to God, and to God alone. Apart
from certain medical applications, what actual right do we have to
experiment, Frankenstein-like, with the very stuff of life? ... "
- Prince Charles Windsor, heir to the British throne (Windsor, 1998).

Throughout the history of humankind, there have been those who have
embraced change and those who have clung to the old ways because they felt
at least the risks were known. Few Edisons or Einsteins were properly
recognized during their lifetime. And, since feeding ourselves was the
primary occupation of mankind for most of our recorded and prerecorded
history, changes in food production have been accepted slowly. The first
person to try to scratch out a garden most assuredly heard derisive
laughter as the mighty hunters headed off in pursuit of meat. So, we
should not be surprised that eons of history are being replayed as we
enter the era of biotechnology. As the fates of human society and crops
have been inextricably intertwined since the dawn of civilization, an
appreciation of our agricultural past may guide us in addressing societal
concerns and also in ensuring minimal negative consequences from
scientific pursuits.

Farmers have embraced the new technology because it makes them more
efficient, protects or increases yields and reduces their reliance on
chemicals that, other things being equal, they would prefer not to use.
Crops enhanced by biotechnology are being grown on nearly 110 million
acres in 13 countries. Food ingredients produced from biotech crops are
found in thousands of food products consumed worldwide. However, while no
unequivocal evidence of harm to our health or the environment from these
crops is known or expected, there is an intense debate questioning their
value and safety.

Societal anxiety over this so-called genetically modified (GM) food is
understandable, and it is fueled by a variety of causes, including
consumer unfamiliarity, lack of reliable information on the current
safeguards in place, a steady stream of negative opinion in the news
media, opposition by activist groups, growing mistrust of industry, and a
general lack of awareness of how our food production system has evolved.
The scientific community has neither adequately addressed public concerns
about GM foods nor effectively communicated the value of this technology.
Clearly, societal acceptance is pivotal to the continued development and
application of biotechnology in food and agriculture.

Two decades ago, many agricultural scientists rightfully saw the emerging
recombinant DNA technology as a potent tool in enhancing crop productivity
and food quality while promoting sustainable agriculture. Much of this
early excitement and expectation was met with successive breakthroughs in
scientific research on plant gene transfer methods, identification of
valuable genes, and the eventual performance of transgenic crops. Plant
breeders saw the technology as an additional means of crop improvement
that could complement existing methods. For the first time, plant breeding
was subjected to rigorous testing, and a regulatory framework was
developed to oversee the commercialization of GM crops on a case-by-case
basis. There has been widespread acceptance and support for biotechnology
from the scientific community. Accumulated experience and knowledge of
decades of crop improvement combined with expert judgment, science-based
reasoning and empirical research has led to scientists' confidence that GM
crops may pose no new or heightened risks that could not be identified or
mitigated, and that any unforeseen hazard will be negligible, manageable,
or preventable. Risks from GM crops should be monitored and measured, but
concerns about these risks must also be balanced against the enormous
benefits from this technology and weighed against alternative options. The
strong trust that the American public has in its regulatory agencies (FDA,
USDA, and EPA) has helped gain higher public acceptance of GM food in this
country than in other nations.

Mutant Food and Monarch Butterflies

Despite the promised benefits, global negative reaction to GM crops ranges
from mild unease to strong opposition. Typical questions asked about GM
crops include: Is it ethical for scientists to modify living organisms
around us? Is it morally right to tamper with our food supply? Is the
genetic modification of crops inherently hazardous? Despite the built-in
safeguards, can we unwittingly make our foods unsafe? What about the
long-term consequences of consuming such foods? Do GM crops affect the
environment or the wild ecosystem, reducing crop biodiversity, beneficial
insects, or the revered monarch butterfly? Could these crops lead to the
development of noxious "superweeds"? Are we introducing these crops into
our environment without fully understanding the consequences of such
action? What about genetic pollution? Can these genes be transferred to
other organisms including humans and animals? In addition, there are also
larger and even more important sociopolitical issues such as anxiety about
the control of food and agricultural systems, including questions about
the pervasive impact of globalization.

How can scientists allay public concerns considering the complexities of
these issues? Creating an awareness of agricultural history may provide a
good beginning for our efforts to help alleviate consumer unease about GM
foods. It may also educate scientists about the relevance of the societal
context to our research. Most risk issues related to current GM crops are
not unique when placed in the context of how agriculture was developed
through crop domestication over many millennia and how we have bred modern
crop varieties in the past century. As Frary and Tanksley (2000) put it,
"The issue is not whether we should modify the genetics of crop plants. We
embarked on that road thousands of years ago when plants were first
domesticated. Instead of simply judging the vehicle through which we make
genetic changes, we need to weigh the potential consequences that such
modifications hold for the society and the environment."

Crop Evolution and Human Civilization

Agriculture evolved independently in many places on this earth, but the
earliest evidence of farming dates 10,000 years ago in present day Iraq
(Heiser, 1990). For much of the 200,000 or so years prior to agriculture,
humans lived as nomadic hunters, gatherers, and scavengers surviving
solely on wild plants and animals. Subsequent domestication of these wild
plants and animals from their natural habitats launched agriculture, thus
radically transforming human societies. This occurred initially in the
Fertile Crescent, the Andean region in South America, Mexico, and parts of
Asia, but diffused throughout much of the globe. A change from the nomadic
lifestyle to farming led us to become community dwellers, eventually
spawning the development of languages, literature, science, and technology
as people were freed from the continuous daily task of finding food. Some
regions caught on much faster than others, by margins of thousands of
years (Diamond, 1999).

Plants have also evolved or, more accurately, they have been changed
rapidly by human intervention (Harlan, 1992). Every crop plant grown today
is related to a wild species occurring naturally in its center of origin,
and progenitors of many of our crops are still found in the wild. Early
humans must have tried eating thousands of feral plant species from a pool
of a quarter of a million flowering plants before settling down on less
than one thousand such species, which were subsequently tamed and adapted
to farming. A little over 100 crop species are now grown intensively
around the world, with only a handful of them supplying us with most of
what we now eat. Through a process of gradual selection, our ancestors
chose a very tiny section of the wild plant community and transformed it
into cultivated crops. Some profound alterations in the plant phenotype
occurred during such selection, and these include determinate growth
habit; elimination of grain shattering; synchronous ripening; shorter
maturity; reduction of bitterness and harmful toxins; reduced seed
dispersal, sprouting and dormancy; greater productivity, including bigger
seed or fruit size; and even an elimination of seeds, such as in banana.
These changes reduced the survivability of crops in the wild, and thus a
feature that transcends all of our crops is the reduction of weedy traits
from wild plants. Present crops are thus totally dependent upon human care
for their survival, and modern crop varieties would persist in the wild
"no longer than a Chihuahua would last in the company of wolves"
(Trewavas, 2000).

Most crops that supply our food were thus obtained at the end of the Stone
Age, often from a relatively narrow pool of extant wild genetic diversity.
Additional diversity arose within such cultivated crops through new
mutations and natural hybridization, and through judicious selection and
perpetuation by farmers who maintained them as land races. Varied uses and
preferences brought forth further diversification such as in corn
(popcorn, sweet corn, dent corn, broom corn, and flour corn for tortilla
and corn bread) or the derivatives of ancestral cabbage (kale, kohl rabi,
brussels sprouts, cabbage, cauliflower, and broccoli).

With the advent of transoceanic navigation and the "discovery" of the New
World, crops were moved around the world rapidly, often achieving
prominence in adopted homes far beyond their natural centers of origin or
domestication. For instance, the United States is the leading producer of
corn and soybean in the word, yet these crops are native to Mexico and
China, respectively. The world's largest traded commodity, coffee, had a
humble origin in Ethiopia, but now much of it is produced in Latin America
and Asia. Florida oranges have their roots in India, while sugarcane arose
in Papua New Guinea. Food crops that are now so integral to the culture or
diet in the Old World, such as the potato in Europe, chili pepper in
India, cassava in Africa, and sweet potato in Japan, were introduced from
South America. For that matter, every crop in North America other than the
blueberry, Jerusalem artichoke, sunflower, and squash are borrowed from
elsewhere!

A few sources of our food are also recent domesticates. Chinese gooseberry
occurs wildly in China and is not edible. But careful breeding made it
palatable, and it was re-christened "Kiwi fruit" in New Zealand after its
introduction there early in the 20th century. The modern strawberry with
big fruits is a product of the accidental crossing of two wild species
from Virginia (United States) and Chile in France in the mid-18th century.
Rapeseed, grown in India for centuries, was altered recently through
classical breeding to eliminate the toxic erucic acid and smelly
glucosinolates to result in canolaCanadian oil. Triticale, a completely
new crop, was artificially sythesized a few decades ago by combining the
genomes of wheat and rye (two distinct genera that do not interbreed in
nature). It is now grown on over three million acres worldwide. Modern
bread wheat itself is also a fairly recent crop in the evolutionary time
scale, having arisen only about 4,000 years ago through hybridization of
tetraploid (pasta or durum) wheat with inedible goat grass.

From Mesopotamia to Mendel

While humans have always molded the evolution of crop plants, such changes
imposed by farmers occurred over several millennia, leading to rich crop
diversityespecially in traits related to their planting or consumption. At
the same time, global population grew very slowly until the mid-19th
century. It took 1,800 years for the global population to climb from an
estimated 300 million around the time when Christianity began, to reach
its first billion. But it took only 12 years to add the last billion,
rising from five billion people in 1987 to six billion two years ago.

Fortunately, parallel scientific developments in agriculture ensured that
food production kept pace with the population explosion of the past
century (Conway, 1999). Beginning with Mendel's study of peas, knowledge
of genetics helped usher in scientific crop development, resulting in
high-yielding varieties. Food production increased in every part of the
world in the past few decades, including in Africa. Per capita food
consumption has also increased steadily everywhere except in parts of
sub-Saharan Africa. In the United States and Canada, where such scientific
developments and their applications were most intense, one average farmer
now produces enough to feed nearly 150 people! In crops subject to
intensive scientific attentioncorn, wheat, and ricethe productivity levels
increased severalfold. For example, U.S. corn growers averaged 26 bushels
of corn per acre in 1928 and 134 bushels per acre in 1998 (National Corn
Growers Association, 2001).

Such a prodigious increase in agricultural production was underpinned by
scientific crop improvement methods along with other developments,
including the use of irrigation, improved soil fertility management,
mechanization, and control of diseases and pests (Conway, 1999). To
develop better crop varieties, scientists have used an array of tools.
Artificial crossing, or hybridization, helped us assimilate desirable
traits from several varieties into elite cultivars. When desired
characteristics were unavailable in the cultivated plants, genes were
liberally borrowed from wild relatives and introduced into crop plants.
When a crop variety refused to mate with the wild species, various tricks
were employed to force them to intermingle, such as the use of the
carcinogenic chemical colchicine or by rescuing the hybrid embryos with
tissue culture methods. Hybrid vigor was exploited in crops such as corn
and cotton to boost productivity. When existing genetic variation within
the cultivated germplasm was not adequate, breeders created new variants
using ionizing irradiation (gamma ray, x-ray, neutron), mutagenic
chemicals (ethyl methane sulfate, mustard gas), or through somaclonal
variation (cell culture).

Most people who are concerned about modern biotechnology have little or no
knowledge of the processes that have been used to transform crops in the
past. Nor are they likely aware that crops have been continually altered
over time or that, without human care, they would cease to exist. Using a
variety of tools over the past few decades, plant breeders have radically
transformed our crop plants by altering their architecture (such as the
development of dwarf wheat and rice), shortening growing seasons,
developing greater resistance to diseases and pests (all crops), and
developing bigger seeds and fruits (Figs. 1 and 2). These crops are also
more responsive to management and better adapted to diverse ecological
conditions. Improved food quality also resulted through fewer toxins
(canola), better digestibility (beans), increased nutrition (high-protein
corn), better taste, longer shelf life (thus withstanding long
transportation and storage), and enhanced freshness in many vegetables and
fruits. A 1,000-fold increase in the marble-sized wild Lycopersicon
resulted in the modern tomato that can now weigh as much as a kilogram
(Frary and Tanksley, 2000).

Modern farming has steadily increased the supply of relatively safe,
affordable, and abundant food not only in the developed world, but also in
most developing countries. An average American family now spends only 11%
of its income on food and yet has access to better food choices with more
variety and nutrition than ever before. Without scientific developments in
agriculture, we would otherwise be farming on every square inch of arable
land to produce the same amount of food!

Using gene transfer techniques to develop GM crops thus can be seen as a
logical extension of the continuum of devices we have used to amend our
crop plants for millennia. When compared to the gross genetic alterations
using wide-species hybridization or the use of mutagenic irradiation,
direct introduction of one or a few genes into crops results in subtle and
less disruptive changes that are relatively specific and predictable. The
process is also clearly more expeditious, as the development of new
cultivars by classical breeding typically takes from 10 to 15 years. The
primary attraction of the gene transfer methods to the plant breeder,
however, is the opportunity to tap into a wide gene pool to borrow traits,
obviating the constraints of cross-compatible crop species.

Addressing Public Concerns

While direct gene transfer is still a relatively new approach, many
concerns arising from its use may be addressed with the "benchmark" of
conventionally bred varieties, as we have the accumulated experience and
knowledge with the latter for more than a century. While it seems logical
to express a concern such as "I don't know what I am eating with GM
foods!" it must be remembered that we really never had that information
before with classically bred crops. With GM crops, at least we know what
new genetic material is being introduced, so we can test for predictable
and even many unpredictable effects. Consider, for example, how
conventional plant breeders would develop a disease-resistant tomato. They
would introduce chromosome fragments from its wild relative to add a gene
for disease resistance. In the process, hundreds of unknown and unwanted
genes would also be introduced, with the risk that some of them could
encode toxins or allergens, armaments that wild plants deploy to survive.
Yet we never routinely tested most conventionally bred varieties for food
safety or environmental risk factors, and they were not subject to any
regulatory oversight. We have always lived with food risks, but in the
last few decades we have become increasingly more adept at asking
questions.

To address the concern about long-term health consequences of GM foods, it
is instructive to recognize that we worried little about such impacts when
massive amounts of new proteins (and unfamiliar chemicals) were introduced
into our foods from wild species or when unknown changes were created
through mutation breeding. When new foods from exotic crops are
introduced, we often assimilate them easily into our diets. What's more we
rarely, if ever, before asked the same questions that we now pose about GM
crops. Many so-called functional foods, health foods, and nutraceuticals
have been entering into the mainstream American diet lately, with little
or no regulation or testing. We do not question the long-term health
implications of these food supplements, even though they involve
relatively large changes in our food intake. In contrast, the GM foods
currently on the market have been tested extensively and judged to be
substantially equivalent to their conventional counterparts, with just one
or two additional proteins present in miniscule amounts (introduced into a
background of thousands of proteins). And, those proteins are broken down
either during processing or digestion, with little long-term consequence.
In food products such as oil, starch, and sugar, such proteins are not
even found. A nagging potential problem with a new protein in food is that
it could be a potential allergen. As most food allergens are now well
studied, we know that they are found in few defined sources (peanut and
other grain legumes, shellfish, tree nuts, and a handful of other foods)
and share many similar structural features. Moreover, they must be present
in huge proportions in our food, and we must be sensitized to them over
time for them to cause any adverse effects. Thus, it is highly unlikely
for new allergens to be introduced into our food supply from GM plants.

Historical Absence of Zero Risk

There is no such thing as safe food, and there never has been! That is not
to suggest that all of our foods are dangerous, only an acknowledgment
that trace levels of such contaminants as toxins and carcinogens are
present in everything we eat. But a primary rule of toxicology,
articulated over 400 years ago by Paracelsus, refers to the importance of
dosage: "Every substance is a poison, but it is the dosage that makes it
poisonous" (Poole and Leslie, 1989).

While not alarming, our daily food naturally contains thousands of
chemicals, and many of them are shown to be carcinogenic or hazardous in
lab animal studies with huge doses. We consume roughly 5,000 to
10,000 natural toxins daily, as plants have evolved to produce an array of
chemicals to protect themselves against pests, diseases, and herbivores
(Ames et al., 1990a). For instance, roasted coffee has over
1,000 chemicals, of which 27 have been tested and 19 of them found to be
rodent carcinogens (Ames and Gold, 1997). The fat-soluble neurotoxins
solanine and chaconine are present in potatoes and can be detected in the
bloodstream of all potato eaters (Ames et al., 1990b). Naturally then,
when crops are bred for resistance to pests by transferring genes through
conventional methods, the resistance is often accompanied by an increase
in such toxic compounds.

Thus, it is not true that we never had problems with conventionally bred
varieties. Any crop variety found to pose a real health risk was promptly
removed from the market, but those varieties (in contrast to GM crops)
were never routinely tested. One pest-resistant celery variety produced
rashes in agricultural workers and subsequently was found to contain
6,200 ppb of carcinogenic psoralens compared to 800 ppb in the control
celery (Ames et al., 1990). This celery was removed from cultivation and
that was also the case with the potato variety Lenape, which contained
very high levels of toxic solanine.

We have always learned from trial and error with all innovations.
Similarly, crop improvement practices evolved over time with continued
refinement. It is common, though, for human nature to generate an
exaggerated fear of new innovations while perceiving older or "natural"
products as always more benign. Huber (1983) discusses this double
standard in the larger context of risk regulation. We have always been
lenient toward existing known and greater hazards, even as we create
"gatekeepers" to minimize new risks. Thus, we fail to recognize and
"exorcise" much larger older risks.

While most food hazards arise from pathogens such as Escherichia coli
0:157, Listeria monocytogenes, and Salmonella enterica along with
mycotoxins produced by fungi (and thus a function of food storage and
handling), certain foods containing toxic compounds are known to produce
adverse health consequences over time. Cassava, eaten by a large
population in Africa, contains cyanogenic glucosides, which cause limb
paralysis if consumed before extensive processing. Solanin in tomato and
potato is known to cause spina bifida. Vetch pea, a common legume known
for its hardinessand thus popular in India among poor farmerscontains
highly dangerous neurotoxins that cause untold misery. Phytohemagglutinin,
found in undercooked kidney beans, is toxic. And peach seeds are extremely
rich in cyanogenic glucosides. None of these were subject to any mandatory
testing before they were introduced into the food chain, nor are they
subject to any regulation now. But if the current regulatory standards
imposed on GM crops were to be invoked for traditional crops, most of them
would fail to meet their requirements.

Humans have built-in natural defenses that protect us against normal
exposure to toxins. But, according to Ames and Gold (1997), we have not
evolved to achieve "toxic harmony" with everything we eat, because natural
selection occurs much too slowly and because much of what is in our diet
today was not eaten at all when we were hunter-gatherers.

A balanced mixture of foods normally provides adequate nutrition. However,
none of the crops grown today were selected with our nutritional
requirements in mind. Instead they were chosen intuitively, by our
ancestors, from among the edibles that could be found around them. Thus,
the most important food crop in the developing worldricehas no provitamin
A and little iron in its endosperm. This has led to horrific problems,
such as blindness among millions of children due to vitamin A deficiency,
and iron-deficiency anemia in nearly a billion women dependent on a rice
diet. Biotechnology research, far from causing any new food safety
problems, has already demonstrated its potential in enhancing the
nutritional quality of our food and is also being employed to reduce
harmful toxic compounds that exist in our food.

What about the Environment?

All of us have to eat to live, and organized food production is the most
ecologically demanding endeavor we have pursued. Agricultural expansion
over the millennia has destroyed millions of acres of forestland around
the world. Alien plant species have been introduced into non-native
environments to provide food, feed, fiber, and timber, and as a result
have disrupted local fauna and flora. Certain aspects of modern farming
have had a negative impact on the biodiversity of crop plants and on air,
soil, and water quality; nevertheless, it sustains and nurtures most of
the world's six billion people with adequate nutrition and affordable food.

How can we address the potential environmental concerns of GM crops in the
context of our experience with traditional crop variety deployment? We
have continuously introduced genes for disease and pest resistance through
conventional breeding into all of our crops. Traits, such as stress
tolerance and herbicide resistance, have also been introduced in some
crops, and the growth habits of every crop have been altered. The risk of
crop gene flow to weedy relatives has always existed, and such "gene flow"
occurs where possible. Thus, it is comforting to recognize that no major
"superweeds" have developed since the advent of modern plant breeding,
although there have been a few instances of crops ever becoming weedy or
of weeds becoming more invasive due to gene transfer from crops. Most
noxious weeds, such as kudzu, water hyacinth, and parthenium, resulted
from the introduction of semidomesticated wild plants into non-native
environments without the checks and balances of their native pests. Yet,
there are probably no dwarf plants among the wild Oryza spp. and Triticum
spp. populations in the Middle East or Asia, despite the fact that we now
have been growing diminutive rice and wheat varieties for decades.

The risk of gene transfer to wild plants is exacerbated when crops are
planted in an area with compatible weedy relatives (as often seen in their
centers of origin), when such species are promiscuous out-crossers
(canola), or, most importantly, when the introduced genes enhance the
reproductive fitness of the recipient weeds (although most genes
introduced into crop plants, conventional or biotech, have little value in
the wild). The risk of gene transfer to weeds is similar with both
conventional and GM crops and is not contingent on how we introduced these
genes into plants. We must be vigilant to ensure that weeds do not become
noxious as a result of any new crop variety. The current case-by-case
testing and monitoring approach with biotech crops is a good regimen for
the future, while the past experience with conventional crops provides
assurance that such risks will be minimal and manageable.

Crop biodiversity is another issue of concern. The popularity of
high-yielding varieties has already narrowed the genetic variation found
in major crops. Biotechnology, if employed strategically, can reverse this
through the recovery of older varieties that were discarded for lack of
certain features (such as resistance to new disease strains), because
modern gene transfer can restore such traits. Biotechnology research is
also enabling the development of better methods for ex situ preservation
of germplasm, such as cryopreservation, whereby valuable germplasm is
being stored and thus saved from extinction.

The introduction of corn with a single transferred Bt gene has led to some
concern about its ecological impact. While this concern should not be
dismissed, it should be balanced with our hindsight and experience with
corn itself, an introduced alien species now grown on 75 million acres in
the United States, where none existed about 1,000 years ago. A crop
introduced into a new environment entails the wholesale introduction of
thousands of new genes. When grown on massive amounts of land, it exerts
considerable ecological impact on the native fauna and flora, including
beneficial insects. In contrast, the introduction of one or two genes into
this background of 50,000 genes present in corn will have relatively less
effect on the environment. While the initial fear about the reported
damage to monarch butterflies from Bt corn has not held up in additional
studies, one also needs to consider the negative impact of alternate
practices (such as pesticide sprays) and recognize the potential for
positive impacts on beneficial insects by the GM crop due to the
specificity of the insect target(s).

For that matter, any concern about "gene pollution" pales in comparison to
the massive "risk" of alien crop introduction, as 95% of the crop area in
the United States now consists of such introduced crops. Concern about
horizontal transfer of genes from GM crops to other organisms, such as
bacteria, has also been expressed. But it appears highly unlikely that the
risk is dependent upon the method of gene introduction. An inherent
feature of biotechnology is that it lends itself easily to molecular
detection of introduced genes, but a true measure of risk can only come in
comparisons with classically bred crops where little or no such studies
have been performed. Concerns such as random gene insertion, gene
instability, and genomic disruption due to gene transfer have been
expressed, but they are unlikely to be unique to GM crops or of any
significance considering our current knowledge of genomic flux in plants.
Worries about mixing genes from unrelated species ignore the history of
plant breeding and the existing overwhelming sequence similarity of genes
across kingdoms. Nevertheless, scientific research aimed at risk analysis,
prediction, and prevention, combined with adequate monitoring and
stewardship, must continue so that negative ecological impact from GM
crops will be kept to a minimum. Most problems raised by science can be
solved by additional science itself. For example, appropriate promoters
may ensure that pollen will not express genes toxic to beneficial insects,
while gene expression strategies, such as sterile pollen, could reduce the
risk of gene flow.

One must also recognize the potential positive impact of GM crops on the
environment, such as decreasing agricultural expansion to preserve wild
ecosystems; improving air, soil, and water quality by promoting reduced
tillage, reducing chemical and fuel use; improving biodiversity through
resuscitation of older varieties and promotion of beneficial insects; and
cleaning up contaminated soil and air through phytoremediation.

As we chart ahead with more exciting developments in biotechnology, such
as genomics, and grapple with issues arising from consumer acceptance of
innovations, historical knowledge on societal adoption of technological
innovations may provide some valuable perspectives to scientists. Many
innovations that would be good candidates for generating consumer
apprehension and concern today were introduced in the past without concern
because the public was less informed about innovation. The precautionary
principle was never invoked to ensure the scientific certainty that crop
varieties developed using nuclear irradiation or chemical mutagens were
safe. And food labeling was never demanded for bread wheat improved with
the addition of hundreds of unknown goat grass genes.

Many other innovations that are now commonplace in our lives were met with
skepticism and opposition when first introduced. Such fear of technology
was especially more pronounced in food-related innovations (e.g.
Pasteurization, canning, freezing, the microwave oven). However, once
consumers recognize that new innovations can enhance their quality of life
and once they understood that risks are either minimal or manageable, such
technology eventually could enjoy public acceptance. This includes even
those "disruptive" technologies that replace older ones (e.g. cars versus
horse buggies, compact disc versus cassette tape). Nevertheless, there are
historical instances of useful innovations that have not been readily
accepted due to a variety of reasons, such as recalcitrance to adapt (e.g.
Dvorak versus QWERTY keyboard), entrenched economic interests opposing
change (e.g. the metric system in the United States; Beta versus VHS
videotape), ideological opposition (e.g. plant breeding during Stalin-era
Soviet Union by Lysenko), exaggerated notions of risk (e.g. food
irradiation), ill-timed product introductions, and serious conflicts with
societal values and beliefs.

Humans and crops will always be mutually dependent on each other's
survival, and the guided evolution of crops will continue but increasingly
will be more knowledge-based and responsible. An appreciation of the
history of agricultural development however may provide us with a useful
roadmap for devising appropriate strategies to informing and rationalizing
societal responses to crop improvement. Paraphrasing the American
philosopher George Santayana, ignoring history may condemn us to repeat
it, but an understanding of the past may as well lead us to an enlightened
future.

Acknowledgments
I am grateful to many contributors to my Internet discussion list
Agbioview (http://www.agbioworld.org) for enriching my knowledge on these
issues. I thank Gregory Conko, Tom DeGregory, Paul Gepts, Dan Holman,
Alan McHughen, and Neal Stewart for helpful comments on the manuscript.

Literature Cited
* Ames BN, Gold LS (1990) Chemical carcinogens: too many rodent
carcinogens. Proc Natl Acad Sci USA 87: 7772-7776
* Ames BN, Gold LS (1997) Pollution, pesticides and cancer misconceptions.
In R Bate, ed, What Risk? Butterrworth-Heinemann, Boston, pp 173-190
* Ames BN, Profet M, Gold LS (1990a) Dietary pesticides (99.99 percent all
natural). Proc Natl Acad Sci USA 87: 7777-7781
* Ames BN, Profet M, Gold LS (1990b) Nature's chemicals and synthetic
chemicals: comparative toxicology.Proc Natl Acad Sci USA 87: 7782-7786
* Conway G (1999) The Doubly Green Revolution. Comstock Publishing
Associates, Ithaca, NY
* Diamond J (1999) Guns, Germs and Steel: The Fates of Human Societies.
W.W. Norton, New York
* Frary A, Tanksley S (2000) The origin of crop species-accelerated
evolution with mankind at helm. SCOPE-GM Food ControversyForum.
http://scope.educ.washington.edu/gmfood/commentary/show.php?author=Frary
(April 3, 2001)
* Harlan J (1992) Crops and Man. American Society for Agronomy and Crop
Science Society of America, Inc., Madison, WI
* Heiser CB Jr (1990) Seed to Civilization: The Story of Food. Harvard
University Press, Cambridge, MA
* Huber P (1983) Exorcists vs. gatekeepers in risk regulation. Regulation
7: 23-32
* National Corn Growers Association (2001) Corn Production in the U.S.:
Hinton Cal. http://www.ncga.com/03world/main/index.html (April 3, 2001)
* Poole A, Leslie GB (1989) A Practical Approach to Toxicological
Investigations. Cambridge University Press, Cambridge, UK
* Santayana G (1998) The Lite of Reason. Prometheus Books, Amherst, NY
* Swift Jonathan (1727) Gulliver's Travels, Unabridged Edi-tion, 1999.
Dover Publications, Albuquerque, NM
* Trewavas A (2000) GM is the best option we have. Agbio-view.
http://www.agbioworld.org/newsletter_wm/index.php?caseid=archive&newsid=249
* Windsor, Prince Charles (1998) Seeds of disaster. Daily Telegraph,
London, June 10, 1998