Flashcards in BIO220 Lecture 20 Deck (61):
Right now, we are in the ___ period
- last 2.68 million years
- ice age with alternating glacial & interglacial periods
Humans emerged ___ years ago
Agriculture is a ____ phenomenon, which appeared in the last ___ years. This means that it appeared in a ___ period.
post-glacial (Holocene epoch);
we are currently living in the ___ epoch of the quaternary period
early humans evolved & migrated as...
One theory of ____ states that __ and homo sapiens are very similar
hominid evolution and dispersal;
What was the last area to be colonized by homo sapiens?
Why are fruits good foods?
They are supposed to be eaten (by animals for dispersal)
Why are seeds & tubers good food?
energy-storing organs (complex carbs & sugars)
Humans are not adapted for eating plant foods. The foods that we eat has to be...
- high nutritional quality
- less defended
___ selection was used to make plants more edible
agriculture evolved ___
independently in different areas
cultural component of agriculture
societies have to learn (from older generation) how to store seeds, weed, plant...
lentils have symbiotic relationship with ___ to get ___
legumes are good sources of...
which kind of seeds are best for humans? for plants?
humans: seeds that don't shatter because they are easier to collect
plants: seeds that shatter so it disperses genetic material
grasses that we eat
legumes that we eat
- chick peas
fruits that we eat
What are key evolution innovations for grass agriculture?
- non-shattering seed heads
- amylase evolution
ancient agriculture innovations
- fish net
- irrigation channels
- domestication (-> evolution of lactose tolerance)
- crop rotation, draft animals (Middle Age)
- exchange of crops, animals, technology (1492)
- no more nomadism
sedentary culture lead to the development of...
Limits of primitive agriculture
- limited area for growth (temperature > water > NPK)
- edaphic (soil) factors: moisture, fertility
- planting same things in same area -> insects, disease, bad yield
seeds that fall too close to adult tree will die due to established predators in that area
- keeps too many of the same species growing in the same area
The first population boom lead to...
who made artificial fertilizers?
John Bennet Lawes of Rothamsted (different concentrations of N, P, K, Mg)
How was edaphic factors solved by agricultural sciences?
add things to soil to replenish lost nutrients
- fertilizer (chemicals)
- animal poop add N (organic)
Where do organic fertilizers & chemical fertilizers differ?
organic matters will also affect soil texture & water retaining qualities, but chemical ones won't
which chemical fertilizers had the best effect?
N fertilizers come from...
high nitrate minerals
chemical creation of ammonia
natural gas + atm nitrogen + catalyst + pressure -> ammonia
HB process produces ___ ammonia per year, and uses ___% of the world's natural gas supply
500 million tons;
consequences of HB process
- mining towns abandoned
- wars, explosives
- 1/2 of N in our bodies is from HB
- meat production
- 1/2 of world is being fed with N from HB
How has new technology overcome previous agriculture limitations?
- irrigation brings water to dry areas
- fertilizer supplies soil with nutrients
- industrial chemistry makes fertilizer
Life history theory of plants: how has this been affected by new agricultural technologies?
plant allocations can all go towards seed production because humans prevent competition, insect attacks, need for nutrients
life history of plants
plants allocate resources to:
- growth (tall = more light, better seed dispersal)
- root system: more water & nutrients
- artificial selection
the Green Revolution
- used plant breeding techniques to evolve high-yielding dwarf crop varieties (HYV)
- high-intensity cultivating techniques
high yielding dwarf varieties
a semi-dwarf rice variety that could produce more grains of rice per plant when grown with certain fertilizers and irrigation
who founded the Green Revolution?
HYV are unable to...
- when plants detect neighbours, they grow tall and skinny
Green Revolution techniques lead to a...
exponential rise in yield, but began leveling in mid-1990s
- Green Revolution techniques can't keep up with human growth anymore
Now that yields have began to level, how to we support a still-increasing population?
Consequence of babying plants
- labour intensive
- use exhaustible natural resources w/ limited supplies
- pollution to surrounding areas (groundwater, poison non-target organsims)
- biocides develop superbugs, addictive
what is the preferred antibiotic nowadays? Why?
penicillin is so resistant that it can't be used anymore
why don't plants need to worry about competition anymore?
- mechanized cultivation
why don't plants need extensive roots anymore?
why don't plants need defense anymore?
cultivation & irrigation leads to long-term...
degradation of soils (build-up of salt)
which is better: annual wheat vs. perennial wheat
annual wheat: good for people
perennial wheat: good for plant
Only lives for 1 year
- Shallow root system
- More yield
- Susceptible to disturbances
Lives for long time
- Extensive root that can provide soil structure
- More resilient to disturbances
- But less yield
2 types of maize production
1. slash & burn
slash & burn vs. mechanized costs & yield
cost: mechanized so much more labour and material intensive
yield: mechanized 4x more
...but is it worth it?
modern agriculture depends on..
cost of food is tied to...
cost of petroleum & electricity
why is cost of food going up?
we are adding so much stuff in our food to improve yield
with current technology, increasing food supply requires...
burning more fuel & clearing more land