Aldo Leopold, who lived from
1887 to 1948, was one of America's most influential environmental
thinkers. A forester, conservationist and author, he once wrote: "To
keep every cog and wheel is the first precaution of intelligent tinkering."
His point was that all the different plants and animals in an ecosystem,
whether we realize it or not, play roles within it.
Biological diversity helps
an ecosystem adapt to changes, including threats, from the environment.
One species of animal will outrun a predator better than another. If
drought or disease kills one kind of plant, a hardier cousin may survive.
Even a single species of plant typically consists of many slightly different
varieties. Those plant varieties carry genes for a wide assortment of
traits – from size to flavor to disease resistance. The greater the
genetic diversity of a plant species, the less likely it is that one
single threat – such as a virus, bacterium, drought, flood or
predator – can destroy the species. That's important not only for
the species itself, but for other plants and animals that depend on
it for their survival. Leopold believed in preserving genetic diversity
and would have likely agreed with Michael Pollan's argument that when
it comes to food crops, the genetic diversity we find in nature should
be protected and preserved. A diverse gene pool enables those crops
to withstand a broad range of environmental threats.
In The Botany of Desire,
Michael Pollan explores risks inherent in one of the most widespread
practices in modern agriculture. It's called monoculture, and
it refers to cultivation of single or very similar varieties of a food
crop on large acreages. In many cases, the variety is one that dominates
the marketplace, like the Russet Burbank potato, whose shape makes it
a favorite for cutting French fries, or one of the few apple varieties
commonly seen in supermarkets. Monoculture may offer economic advantages,
but Pollan argues that it brings serious environmental risks.
Very simply, a
vast field of identical plants will always be exquisitely vulnerable
to insects, weeds, and disease----to all the vicissitudes of nature."
– Michael Pollan, The Botany of Desire.
Maintaining biodiversity, Pollan
argues, is like an insurance policy. By growing multiple varieties of
a crop, we increase the chances that if one fails, another will have
the genetic traits that enable it to thrive. Maintaining pest resistance
through biodiversity can reduce the need to use pesticides.
But others argue for protecting
crops by giving them genes from other organisms like bacteria – genes
that endow those plants with resistance to pests or diseases. The process
of inserting genes from one organism into the cells of another in the
laboratory is called genetic engineering. Today, many of
the most widely grown crops in America, like corn and soybeans, are
genetically engineered. The practice is the focus of an international
The controversies over biodiversity
and genetic engineering raise important questions about farming:
This lesson encourages students
to investigate the human role in developing a cultivar (cultivated variety)
of their choice (wheat, soybean, corn, cotton, or canola). Students
will explore the relationship between cultivars and wild varieties,
discuss the need for cultivars, and discuss risks from modern agricultural
National Science Education Standards
History and Nature of Science
As a result of activities in grades 5-12, all students should develop understanding of:
Science as Inquiry
Science and Technology
This lesson prompts thought and discussion on controversial human efforts to alter plants, especially recently by means of genetic engineering. This section provides context for what we mean by "intelligent tinkering" with nature.
ALDO LEOPOLD AND INTELLIGENT TINKERING
Aldo Leopold prompted a great deal of thought and debate about the idea of intelligent tinkering. The following excerpt from his book Round River provides some insight into his views:
"Conservation is a
state of harmony between men and land. By land is meant all of the things
on, over, or in the earth. Harmony with land is like harmony with a
friend; you cannot cherish his right hand and chop off his left. That
is to say, you cannot love game and hate predators; you cannot conserve
the waters and waste the ranges; you cannot build the forest and mine
the farm. The land is one organism. Its parts, like our own parts, compete
with each other and co-operate with each other. The competitions are
as much a part of the inner workings as the co-operations. You can regulate
them—cautiously—but not abolish them. The outstanding scientific
discovery of the twentieth century is not television, or radio, but
rather the complexity of the land organism. Only those who know the
most about it can appreciate how little we know about it. The last word
in ignorance is the man who says of an animal or plant:
'What good is it?' If the land mechanism as a whole is good, then
every part is good, whether we understand it or not. If the biota, in
the course of [eons], has built something we like but do not understand,
then who but a fool would discard seemingly useless parts? To keep every
cog and wheel is the first precaution of intelligent tinkering."
– Leopold, Aldo: Round River, Oxford University Press, New York, 1993, pp. 145-146.
SOME QUESTIONS AT THE HEART OF THE DEBATE
Although we might agree that understanding the "complexity of the land organism" is important, there is no consensus on the degree of "tinkering" we should be doing with domesticated crops. Some questions can help frame a discussion on this topic:
*In 1876, countries around the world were invited to build exhibits to celebrate the one-hundredth birthday of the United States. The Japanese government constructed a beautiful garden filled with the sweet-smelling blooms of kudzu. American gardeners were captivated by the plant and used it for a variety of ornamental purposes. By the 1920s, the plant was used to feed animals and then, a decade later, to control erosion. In the 1940s, farmers were paid to grow the plant. However, because the kudzu vine grows so fast and is so prolific, enveloping trees and denying them sunlight, it was recognized as a weed by the USDA in the 1970s and listed by the U.S. Congress as a Federal Noxious Weed in 1997. With the propensity to replace existing vegetation, kudzu causes much economic and ecological damage. Some government publications estimate that kudzu causes more than $IOO million of damage per year in the U.S. According to another source, which factors in $336 million of lost productivity in forests, losses from kudzu are "greater than $500 million per year" (Blaustein, Richard J. 2001).
The last word in ignorance is the man who says of an animal or plant: 'What good is it?' If the land mechanism as a whole is good, then every part is good, whether we understand it or not. — Aldo Leopold
EXTENDING TO OTHER VARIETIES AND GENETIC MANIPULATION
As a short writing assignment, have students respond to the following:
Books and Journals
Damania, A.,J., Valkoun, G. Willcox, and C. Qualset, eds. (1998). The Origins of Agriculture and Crop Domestication, 1st ed. International Center for Agricultural Research in the Dry Areas, Aleppo, Syria.
de Candolle, A. (1992). Origin of Cultivated Plants, 1sh ed. Cambridge, U.K.
Diamond J (1997) Guns, Germs and Steel, A short history of everybody for the last 13,000 years. Viking UK Random House ISBN 0-09-930278-0
Frankel, O. H., A. H. D. Brown, and J.J. Burdon. (1995). The Conservation of Plant Biodiversity, 1st ed. Cambridge University Press, Cambridge, U.K.
Gepts, P. (2001) Origins of plant agriculture and major crop plants In M. K. Tolba, Ed., Our Fragile World: Challenges and Opportunities for Sustainable Development, EOLSS Publishers, UK, pages 629-637.
Gepts, Paul. Chapter 13. Ten thousand years of crop evolution. In Chrispeels, Maarten J.; Sadava, David E. (editors) (2003). Plants, Genes and Crop Biotechnology, 2nd ed. Jones and Bartlett. ISBN 0-7637-1586-7.
Hancock, J.F. (2004). Plant Evolution and the Origin of Crop Species, 2nd ed. CAB International, Wallingford, UK. ISBN 0-85199-685-X.
Harlan J. R. (1992). Crops and Man, 2nd ed. American Society of Agronomy, Madison, WI.
Heun MR et al (1997) Site of Einkorn Wheat Domestication Identified by DNA Fingerprinting Science 278:1312-4 DOI: 10.1126/science.278.5341.1312
Lev-Yadun, Simcha , Gopher, Avi, Abbo, Shahal (2000) The Cradle of Agriculture. Science 2 June 2000: Vol. 288. no. 5471, pp. 1602 - 1603 DOI: 10.1126/science.288.5471.
Lev-Yadun S et al. (2000) The cradle of agriculture Science 288471:1602-3
Özkan H et al. (2002) AFLP analysis of a collection of tetraploid wheats indicates the origin of emmer and hard wheat domestication in southeast Turkey Molecular Biology and Evolution19:1797-1801 (2002) PMID 12270906
Smith, Bruce D. (2001) Documenting plant domestication: The consilience of biological and archaeological approaches PNAS | February 13, 2001 | vol. 98 | no. 4 | 1324-1326
Sun, C. et al. (1998) From indica and japonica splitting in common wild rice DNA to the origin and evolution of Asian cultivated rice. Agricultural Archaeology 1998:21-29
Vavilov, N. I. (1997).
Five Continents. Rome: International Plant Genetic Resources Institute;
St. Petersburg: N. I.Vavilov All-Russian Institute of Plant Industry.
Bioversity International (formerly IPGRI)
The world's largest international
research organization dedicated solely to promoting agricultural biodiversity.
Food and Agriculture Organization of the United Nations (FAO)
The largest specialized agency
in the United Nations system working to provide "food security"
for the world.
Consultative Group on International Agricultural Research (CGIAR)
CGIAR is an association of
public and private members supporting a system of 16 Future Harvest
Centers that work in more than 100 countries to mobilize cutting-edge
science to reduce hunger and poverty, improve human nutrition and health,
and protect the environment.
The Global Diversity Trust
An activist site with information
about the importance of plant gene banks.
"An electronic journal devoted
to conservation of crop genetic resources with emphasis on cassava."
An organization that helps
Americans to build a relationship with a farm and receive a weekly basket
of produce. www.localharvest.org/
Botanique is a portal to over
2400 botanical gardens in Canada and the United States. www.botanique.com/
Blaustein, Richard J. 2001.
Kudzu's invasion into Southern United states life and culture. In:
McNeeley, J. A. ed. The Great Reshuffling: Human Dimensions of Invasive
Species. IUCN, Gland, Switzerland and Cambridge, UK. The World Conservation
Corbin, R.A. (2006) Living Science: Human, Student-Inquiry Science Projects for Middle and High School. A guidebook written for the American Society for the Prevention of Cruelty to Animals.
Corley, R. N., A. Woldeghebriel, and M. R. Murphy. 1997. Evaluation of the nutritive value of kudzu (Pueraria lobata) as a feed for ruminants. Animal Feed Science and Technology 68: 183-188.
Everest, J. W., J. H. Miller,
D. M. Ball, and M. G. Patterson. 1991. Kudzu in Alabama. Alabama
Cooperative Extension Service Circular ANR-65, Auburn University, Auburn, Alabama, USA.
Leopold, Aldo: Round River, Oxford University Press, New York, 1993, pp. 145-146.
Pollan, Michael. The Botany
of Desire: A Plant's-Eye View of the World. New York: Random House,