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Lecture 8

BIO220H1 Lecture Notes - Lecture 8: Aeration, Corn Flakes, Sexual Selection

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John Stinchcombe

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Lecture 8: Ecology of Ancient and Modern Food Production
Continued from last lecture 7
Population issues once dominated public discourse, but no longer –why?
Where is the overall issue of human population growth?
Left: Problem with rich countries telling poor countries what to do
oHow to manage populations
oHow citizens make family planning choices
Right: Birth control is morally wrong
So both sides have reasons for dropping issue of human population growth
2 other issues:
o(1) Most politicians think that some growth is essential
oEX: Think that economy should grow every year
Don’t realize to grow 2% per year is exponential growth
o(2) More comfortable to ignore things that seem far in the future
But costs are paid down the road
Is there any way to address population that is not morally offensive?
i.e. (not telling people what to do with their lives)
Consider the film Mother: Caring for Seven Million
oProposition: Human fertility rates fall when women acquire more legal rights, more education, and
access to contraception
oIn these cases, standard to living goes up
oAlso no need to force to make changes into their personal family planning
oSo if raise educational/economic status for living than changes in standard to living and population
growth rate will change
Lecture 8
Food production tied to population growth
Population needs to be fed
Have to extract resources from environment
oGeologically over last 3 million years have been interglacial-glacial periods
Humans as a species emerged about 2 million years ago
Agriculture is a recent phenomenon (last 10 thousand years)
oEspecially recent in the Americas
Corresponds w/ an interglacial period
Staple plant foods
Primitive diet probably opportunistic and unreliable
We now are not adapted to eating leaves
Fruits and seeds, tubers/nuts
oLess well defended against herbivores
oNutrient rich resources
oSo tasty for us to eat because they evolved to attract dispersers to take them
from parent plant to alternative location
Crops of antiquity: artificial selection on native plants
Happened independently in different places

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oFrom cultural innovations and evolutionary innovations on our part and on part
of harvested species
Ancient technical innovations
While humans harvesting/consuming grasses legumes and fruits, were technological
innovation that changed our ability to extract these resources
oFishing by net (innovations can extract protein)
oDomestication of cattle, sheep, poultry
oPlow replaced digging sticks (5 thousand yrs ago)
oMiddle ages: crop rotation (get more product out of area of land by growing
different crops in different years)/draft animals
oAfter 1942: Had global exchanges of crops, animals, tech
Consequence: Previously nomadic lifestyle replaced by sedentary lifestyle where
individuals live in one place, get food from agriculture and live in high density cities
oThis is a really recent technological and cultural innovation in human
Ecological & evolutionary limitations of primitive cropping systems
In early phases crop systems limited
oNot many suitable areas
oMost plants limited by NPK concentration, temperature, water
oEdaphic factors: Soil moisture, fertility
oSoil exhaustion (if keep growing same thing in same place)
Buildup of insects, disease, pathogens
All of these limit agriculture in certain regions
Applied science to attack these limitations
Issues in contemporary agriculture
In 1950s-60s (post WWII)
oPopulations booming
oCoincided with a lot of famines across globe (mass starvations)
oPeople predicting that given agricultural resources at time and population
growth that there would be more famines
So do we change human society or change agriculture?
Development of chemical fertilizers: John Bennet Lawes of Rothamsted
Chemical fertilizers studied systematically at Rothamsted experimental station
Soil Amendments
Have been used for long time
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