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Agriculture and Environment: 

Agriculture and Environment 03.376 ERE3 (WS 2005/2006) Uwe Schneider

Class Topics: 

Class Topics Introduction Evolution of agriculture Environmental impacts of modern agriculture Global environmental change and agriculture Future of Agriculture

Agriculture in human history: 

Agriculture in human history Humans diverged from great apes about 7 million years ago Agriculture developed within the last 11 thousand years More than 99% of time humans have lived as hunters and gatherers

Development of Agriculture: 

Development of Agriculture Ideas presented here are based on Jared Diamond “Guns, Germs, and Steel – The Fates of Human Societies” also available in German: “Arm und Reich – Die Schicksale menschlicher Gesellschaften”

Diamond’s Theory in short: 

Diamond’s Theory in short Certain environmental conditions favored faster development of agriculture in Eurasia Agriculture provided Eurasian farmers means to colonize/enslave/kill hunter and gatherer communities Guns, Germs, and Steel 3. Explains human history (fates of human societies) to great extent

Birthplaces of Agriculture, 1: 

Birthplaces of Agriculture, 1 Mesopotamia (Iran, Iraq) China Southern Mexico The Andes Perhaps a few other places

Birthplaces of Agriculture, 2: 

Birthplaces of Agriculture, 2 Today’s centers of food production (Great Plains in the US, Argentine Pampas, South African Cape region, Southwestern and Southeastern Australia, Ukraine) are not among birthplaces of agriculture! Why?

Common misconceptions: 

Common misconceptions Farming was a conscious decision a discovery an invention an abrupt change of life

Subconscious farming, 1: 

Subconscious farming, 1 Hunters and Gatherers recognize differences in taste, size, and other properties of various plants Selective collection of fruits and seeds Spread of selected fruits and seeds in garbage dumps and latrines or on hunting trails Promotion of favorable genes incl. mutants (Ex: non-bitter almonds)

Subconscious farming, 2: 

Subconscious farming, 2 Animals taken home as pets Indirect selection of pets with specific properties Trial and error Subconscious farming lead to domestication of many plants and animals = Process of making wild plants and animals more suitable for agricultural production

Animal domestication: 

Animal domestication Favorable attributes Low energy diet (Herbivores) High growth rate Herd structure Ability to breed in captivity Peaceful to humans Calm

Animal domestication failures: 

Animal domestication failures Energy intensive diet (Carnivores) Slow growth rate (Gorillas, Elephants) No Herd structure (Antelopes, Big horn sheep) Breed not in captivity (Cheetah) Too violent (Grizzly, African buffalo, Zebra) Too panicking (Gazelles, Deer)

Domestication Examples: 

Domestication Examples

Plant domestication: 

Plant domestication Favorable attributes Big seeds / fruits Annual cycle Ability to store Non-toxic Good taste Easy to carry Self-pollination

Plant domestication failures: 

Plant domestication failures Long time between planting and fruit development (trees) Multi-gene based negative properties (bitterness, toxicity) Animals overriding human selection Frequent cross pollination Combination of above

Plants and Crops: 

Plants and Crops 200,000 wild species globally A few thousands are eaten by humans A few hundred have been domesticated About a dozen species account for more than 80% of the modern world‘s annual crop tonnage (wheat, corn, rice, barley, sorghum, soybean, potato, manioc, sweet potato, sugar cane, sugar beet, banana

Acorns (Oak trees): 

Acorns (Oak trees) Nutritionally valuable, rich in starch and oil Contain bitter tannins (grinding, leaching) Never domesticated Slow growth Eaten by billions of squirrels Bitterness controlled by multiple genes

Strawberries: 

Strawberries Romans tended wild strawberries in their gardens Long time failure to domesticate Competition with thrushes and other berry-loving birds Only recent domestication with nets or in greenhouses

Gray Zone between Hunting and Farming, 1 : 

Gray Zone between Hunting and Farming, 1 Sedentary hunters and gatherers who don’t plant but impact natural growth Seasonal hunters – seasonal farmers Take orphan animals hone as pets first but eventually consuming them Hunting men, farming women

Gray Zone between Hunting and Farming, 2 : 

Gray Zone between Hunting and Farming, 2 Mobile food producers Artificial fires Manipulation of wild trees Slow transition from hunting to farming over thousands of years

To farm or not to farm?: 

To farm or not to farm? Favourable conditions for individual plant or animal domestication not sufficient condition for change of lifestyle The whole package of farming opportunities vs. the whole package of hunting/gathering opportunities matters

To farm or not to farm?: 

To farm or not to farm? Early Farmers Spent more hours working per day Were less well nourished Had more diseases Died at earlier age Could not foresee today’s agriculture Why farm?

Evolution of Farming: 

Evolution of Farming Farming and Hunting were alternative lifestyles competing against each other and against many “mixed economies” Evolution selected the fittest strategy, which ensured highest survival rates  Farming must have had comparative advantage (at least in long run)

Farmers fitness: 

Farmers fitness Higher birth rates allowing for faster population growth More calories per hectare Opportunity to support full time warriors and armies, which win against small hunting communities Higher resistance to nasty germs (after many centuries of coexistence with confined animals)

Dynamic Arguments for Farming: 

Dynamic Arguments for Farming Decline of wild foods (esp. animals) Increase of habitat for domesticable plants and animals Technological changes ease farming Population density and food production Farming yields more calories per hectare Farming tribes “outgun” hunters (Weapons, Soldiers, Germs)

Spread of Agriculture, 1: 

Spread of Agriculture, 1 From birthplaces to neighboring areas “High” East-West or West-East speed “Low” North-South or South-North speed Continental boundaries Human characteristics Preferences / Adaptability Aggression

Spread of Agriculture, 2: 

Spread of Agriculture, 2 High Speed in Eurasia Medium Speed in Africa, Americas Low Speed in Australia Thus, Eurasian agriculture developed faster giving Eurasian farmers the means to conquer peoples from different continents and not vice versa

Fertile Crescent: 

Fertile Crescent

Fertile Crescent: 

Fertile Crescent Mediterrnean climate (mild, wet winters and long, dry, hot summers) Plants must survive long dry season and resume growth rapidly upon the return of the rains (annual cycle, small herbs, put energy into big seeds instead of fibers) 6 wild species are among the 12 major crops today

Fertile Crescent: 

Fertile Crescent Wild ancestors already abundant and productive 1 ton of seed per hectare = 50 kcal of energy/1 kcal of work Some hunters/gathers had settled before they started cultivation Wild flora contained a high degree of „selfers“

Agricultural consequences: 

Agricultural consequences Livestock germs Epidemic diseases Evolution of immune system Steel tools Agricultural places promoted innovation more than other places Writing skills originating in Mesopotamia, Mexico

Deadly gifts from livestock: 

Deadly gifts from livestock

Critique of Diamond’s Theory: 

Critique of Diamond’s Theory “Environmental Determinism” Environment determines everything Does not account for impact of Social developments / institutions Religion Human personalities

To farm or not to farm?: 

To farm or not to farm? Mathematical Approach: Optimization models Solving first order conditions Genetic algorithms Game Theory

Optimization, 1: 

Optimization, 1 Independent computation of utility for alternative strategies Alternative strategies / players are exogenous Fitness = Benefits - Costs

Optimization, 2: 

Optimization, 2 Fitness(s,t) = f (e(t), h(t), s) where s … strategy t … time e … environmental factors h … human factors

Optimization, 3: 

Optimization, 3

Game theory: 

Game theory Accounts for interaction between players (payoff matrix, decision trees) Players optimize according to expected response of other players Stable strategies may not represent pareto optimality (Ex. Prisoners dilemma)

Types of players: 

Types of players Male vs. female Predator vs. Prey Weak vs. Strong Farmer vs. Hunters, Etc., or Same type

Types of Strategies: 

Types of Strategies Food acquisition Hunting Farming Mixed Social behavior Competitive Neutral

Payoff Matrix: 

Payoff Matrix

Payoff Matrix Example: 

Payoff Matrix Example Is there an equilibrium?

Dynamic Games: 

Dynamic Games Dynamic payoff matrix Payoffs in a given period can depend on strategy choice of previous period(s) Solution can yield stable equilibrium, drift, or sudden change Computer algorithms useful