10/3/24
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What is an example of freshwater overuse?
Aral sea
What is the culprit of Aral sea’s freshwater overuse?
Soviet cotton
What was the reason for the Green Revolution and what was the goal?
1960: scarcity of new arable land Goal: increases crop output per area land
What was the purpose of cultivars during the Green Revolution?
• Increased yield • Drought- and salt-tolerant
What were the outcomes of the intensive agriculture during the Green Revolution?
Fertilizer pollution Pesticide pollution Water depletion (irrigation) Fossil fuel use
What would happen without the Green Revolution?
much greater loss of forests, wetlands, damage to other ecosystems
Why are monocultures an issue?
Economically efficient, but risk of “all eggs in one basket” Reduced global diversity of crop plants
Why is pesticide use an issue?
Pesticides gradually become less effective as pests evolve resistance Few pests that survive pesticide (because happen to be genetically immune) Reproduce and pass on pesticide resistance genes to the next generation
Genetically Modified Food Organisms (GMOs)
Organisms whose genetic constitution has been altered by engineers with a specific outcome in mind
What is the result of using GMOs
Organisms grow bigger and faster
What is the purpose of GMOs?
Attempt to ramp up food increase
Artificial selection
manipulating organism’s genetic material by selecting mating, harvest
Artificial selection is a selection of
who mates with who
Examples of artificial selection
different dog breeds All come from same genetic stock (wolves) Teosinte → corn Wild mustard (origin) Cabbage - suppression of internode length Broccoli Kale Cauliflower Kohlrabi
Genetic engineering
adding, deleting, or changing segments of DNA
Recombinant DNA
combination of original DNA plus some modification
What is an example of recombinant DNA?
Bt-protected crops Soil bacterium, Bacillus thuringiensis Produces toxic to defend against predators Toxin-producing gene is taken → Bt endotoxin 95% U.S. soybeans, 85% corn, and 90% cotton GM US = 40% global GMO production)
Scientific Concerns About GMOs (least to most likelihood):
Human health risks - No evidence suggesting GMOs affect human health Can tansgenes for pest resistance “jump” from crops to weeds (–> “superweeds”)? Pests will evolve resistance to Gm crops just as with pesticides?
Socioeconomic & Political Concerns of GMOs
Ethics of “playing God?” Food supply risk? - Adequate testing? Is outside oversight adequate?
Benefits of GMOs
Increase food production without nature conversion Less pesticide use
What is one way people are preserving crop diversity?
Seed banks to preserve native cultivars (“living museums”) E.g., Svalbard Global Seed Vault
Feedlot agriculture
Increased meat consumption → animals raised in feedlots (CAFOs) Concentrated Animal Feeding Operations
What are the upsides of feedlot agriculture?
Energy-rich food Extremely high densities
Downsides of feedlot agriculture
Chickens are confined to small spaces Start to get hyper aggressive Chicken beaks are snipped off