Food

Human nutritional needs Vitamin A : –Too little: increases susceptibility to infection and blindness –Leafy green vegetables; orange fruits –100+ million children; Africa, SE Asia Iodine –Too little: leads to enlarged thyroid, mental retardation –Added to salt –1 in 10 people, especially S and SE Asia Iron –Too little: leads to anemia, infection and fatigue –Found in meat, leafy greens –1 in 3 people in developing world

Foods we eat 30,000 edible plants –Only 14 plants and 9 terrestrial animals supply 90% world’s calories 3 crops provide more than half of calories –Wheat –Rice –Corn

Green revolution to Gene revolution Traditionally: crops improved by conventional breeding, crossing –= artificial selection Genetic engineering may be more precise, quicker

GREEN REVOLUTION In 1950s and 60s, scientists developed new seeds for crops (wheat, corn, rice, etc) that were much HIGHER YIELDING. –Means: more grain produced on each acre Mexico went from net food importer to net food exporter

But... Green revolution seeds require –Lots of fertilizer –Lots of pesticides –Irrigation

Has the Green Revolution ended world hunger? NO There is enough food in the world for everyone to have an adequate diet But, some people have more than enough, and waste food; others cannot purchase enough food to stave off hunger

History of the Green Revolution Norman Borlaug –father of the Green Revolution –winner of Nobel Peace Prize in 1970 Started in Mexico in Within a generation, Mexico had gone from a food importing country to a food exporting country. Plant breeding to create new seed varieties that have higher yields.

Recipe for a Revolution High Yielding Varieties (HYV) seeds –Increased nitrogen absorption potential –Semi-dwarf varieties By 1970: –20% of wheat area and 30% of rice area in developing countries planted with HYV

Recipe for a Revolution Required application of: –Nitrogen Fertilizers –Synthetic Pesticides –Irrigation F1 Hybrids Double-Cropping farmland Continued Expansion of Green Revolution crops –As farmers got increased yields from rice and wheat, they planted more land in rice and wheat at the expense of other crops –Effect on biodiversity?

Social impacts Farmers had larger incomes Stimulated the non-farm economy Improved rural (farmers and others) nutrition because they had more $ to spend Slowed down conversion of land to agriculture But favored large, mechanized farms over small, ``family’’ farms

Green revolution in India

Green revolution problems Requires heavy doses of fertilizer, irrigation, equipment –Fossil fuel use increase Emphasizes rice, wheat (commodity crops) not subsistence crops

Fertilizer use Steady increase from 1950s. Why erratic beginning 1980s?

Land planted in crops Net Result: Drop of per capita acreage - that is land planted per person - this decrease is due to an increasing population which by itself would lead to a decreased per capita if land were not added proportionally, and the additional decrease due to land withdrawal :.24 acres/person 1986:.1 5 acres/person 2000:.1 2 acres/person

Animal agriculture Refers to raising animals for food Includes also fish farming = aquaculture

What do livestock eat? Grasses and other forage crops on 3.5 billion hectares Crop residues By-products of food and fiber processing 1/3 of all the cereal grains grown worldwide (2/3 in the U.S.)

CAFOs Concentrated Animal Feeding Operations

CAFO Chickens with little room to run around in a darkened warehouse Diseases spread easily, so chicken farmers use lots of ______________

CAFO = Concentrated Animal Feeding Operation

Biotechnology Introducing genes from one organism to a crop plant or animal. Herbicide resistance Pesticide resistance

Terminator technology Genes added to crops that make the seeds infertile Therefore, farmers can’t save seeds from their harvest for planting the next season –This is typically done in poor countries Problems : –Farmer must buy seeds every year. –If terminator escaped, wild plants could be made infertile. –The first problem is real; the second problem is mostly hype  plants are infertile, so low fitness

Green to Gene revolution Green revolution yielding to gene revolution Using genetic engineering to develop crops with new traits.

What sorts of traits? Greater tolerance of heat or cold Drought tolerance Herbicide resistance Pesticide expressed in plant Tolerance of poor soils

GMOs Possible advantages –Less fertilizer or water –Need less pesticide application, or safer pesticides –Tolerate herbicides Possible disadvantages –Unintended ecological consequences of releasing GMOs –Increased use of herbicides (``because we can’’) –Possible human health issues (e.g., allergy)

Is animal agriculture good or bad for the environment? Good: –Manure for crops –In some cases, grazing can improve habitat by reducing weeds, increasing biodiversity of plants and insects Special case, low density of animals Bad –Heavy grazing reduces biodiversity –Leads to soil compaction and erosion –CAFOs pollute air and water