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Lecture 20

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John Stinchcombe

BIO220: Lecture 20 Ecology of Ancient and Modern Food Production  Early humans  evolved and migrated as hunter/gatherers  Staple plant foods: (primitive diet) o Opportunistic and unreliable  so had to be mobile and hard to find resources (mortality high) o Humans not adapted for eating leaves, we need to eat things that are easy to digest (fruits, seeds, tubers) o Fruits  seed dispersal o Seeds and tubers  energy storage organs (rich sources of carbs)  Key cultural innovation: non-shattering seed heads  Ancient technical innovations: o Fishing by net o Irrigation channels o Domestication of cattle, sheep, poultry o Crop rotation/draft animals o Humans went from wandering hunter gatherers to being stationary  Limitations of primitive cropping systems: o Crops were limited by areas that weren’t suitable for growth o Overall structure of soils (deep, sandy, oil) o Pathogens Development of chemical fertilizers: Rothamsted  Chemically modifying the soil  Repeated crop harvests known to exhaust soils (nutrients removed rather than recycled)  Add animal poop to soil known since FOREVER  Main chemical benefits are N, P, K. Other benefits come from organic matter improving soil texture and water retaining capacity  Lawes: dramatic growth responses to chemical fertilizers, especially grasses  N fertilizer from high nitrate minerals  Haber-Bosch Process: can take natural gas + aerial nitrogen into ammonia (plants can take it up) o Developed for fertilizer and explosives  Life History Theory: Plants have to allocated resources to growth, competition, defense, reproduction, dispersal (finite amount of resources)  Borlaug ‘The Green Revolution’ o Use conventional plant-breeding techniques (artificial selection and hybridization) to evolve high yielding dwarf crop varieties (HYV)  were usually ones where plants lost their ability to sense their neighbours. And as a consequence, they would remain ve
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