BSCI 124 Lecture Notes

• A. Carbohydrates and lipids for energy (calories)

B. Proteins from body structure (humans cannot make 8 essential amino acids and so need them in their diet)
C. Minerals - inorganic elements such as iron and calcium that are essential for the normal functioning of the body
D. Vitamins - complex organic molecules that are required in very small amounts by living cells

• A. Defined as the maximum number of organisms that can be supported in a given habitat.
• 1. Limitations: water, food (energy), space, disease -- some graphic examples

2. All living organisms require water; can exist a long period of time without food; sex not a necessity
B. Human population
• 1. growth of human population 
• REQUIRED READING
• a. change over time
• 0 A.D. = 200 million

1850 = 1 billion
1930 = 2 billion
1975 = 4 billion
1990 = 5.3 billion
2000 = 6.5 billion
2. population projections
• a. as of Dec 6,2000 the estimate is over 6 million [click here to watch it grow]), growing at a rate of 167 people per minute or 88 million per year. (Population in the US alone; population country by country)

b. the rate of increase peaked in 1965-70 at 2.1% per year, but has declined to 1.6%; rate seems small, but population growth is exponential
c. at the present rate of growth, the world population would double in 43 years although the UN predicts a slower growth rate currently

d. growth with various assumptions -- see figure -- rate of growth at 2.06 children/woman is the replacement rate; 2.17 a slightly higher level; 1.96 a slightly lower rate. Based on 1996 population figures and a growth rate of 2.1 children per woman, the world's population will reach 9.5 billion by 2050.
C. Human food resources: How many people can the earth sustain
• 1. Currently, it takes 1.2 billion metric tons of grain such as wheat, corn, rice, and barley to feed the world's population.

2. Each year an additional 0.25 billion metric tons of grain must be produced to account for the increase in population that year. That is a 21% increase in food production each year.
In perspective- the world population will eat more grain in the next 50 years than has been produced since the rise of agrigulture. 3. From 1984-1990 there was 1% gain in grain production.
4. Food production can be increased, but the long-term solution to the problem of producing enough food lies in controlling the human population growth.
D. Carrying capacity example - bacteria in a rich medium (milk) in a warm room
• 1. The growth begins gradually, and then increases; but since the habitat has finite resources (nutrient), it will
• a. crash by outstripping resources or;

b. gradually adjust population growth with leveling off at carrying capacity without a crash.

• A. Quantity (producing enough calories) and quality (producing food with enough of the right kinds of nutrients)
• 1. Main nutritional problems in developing nations
• a. people who receive fewer calories in their diets than they need are undernourished

b. people who receive enough calories but not enough specific essential nutrients are malnourished
2. Main nutritional problem in developed nations
• a. people who consume food in excess of their nutritional requirements are overnourished

b. diets high in fat, sugar, and salt
• 3. Water availability is also threatened
B. Poverty is the main cause of undernourishment and malnourishment; affects at least 1 billion people.
• 1. The world's poorest people live in developing countries of Asia, Africa,and Latin America where hunger is common.
• a. they do not own land on which to grow food

b. they do not have the money to purchase food
2. Poverty is also a problem in developed nations.
• a. one out of four children in this country live in poverty
C. Humans are too dependent on just a few crops
• 1. there are about 300,000 different plants

2. 3,000 plants are possible food for humans
3. 150 plants are cultivated extensively
4. only 12 plants are major sources of food
• a. cereal crops - wheat, rice, corn

b. root crops - white potato, sweet potato, manioc (cassava)
c. sugar crops - sugar cane, sugar beet
d. bean crops - common beans, soybeans
e. tree crops - banana, coconut
D. Declining genetic diversity in our food crops and agricultural animals
• 1. Wild populations have great genetic diversity
• a. genetic diversity contributes to a species' long-term survival (provides the variation that enables a population to adapt to changing conditions)
2. Domesticated crops have much less genetic diversity
• a. selective breeding results in uniformity because the farmer selects against traits that are not of obvious value (to the farmer)
3. Lower genetic diversity increases the likelihood that domesticated plants and animals will succumb to new strains of disease organisms
• a. disease organisms (bacteria, fungi, viruses) evolve quite rapidly

b. when a new disease strain breaks out in a domesticated population, ALL the population is susceptible
c. a new strain of disease would probably not hurt a wild population much because it is more diverse (genetically); at least some of the population would have genes to resist the pathogen
4. With increasing populations and a demand for industrialization, where will farms exist in densely populated regions of the world?
• a. The problem in Asia

b. The problem in Africa
5. Will the environment survive a rapidly growing population?
Ranking of nations in their use vs. ecological resources

• A. Raise the standard of living in developing countries
• 1. Lower birth rate will naturally follow (historically this has occurred)
• a. U.S. example
• no high school degree - 2.5 children

4 yr. high school degree - 2.1 children
4 yrs. college - 1.8 children
2. First step - providing adequate nutrition and health care facilities
B. Improve existing crops and develop new crops
• 1. Develop/improve crops that are native

2. Examples of nutritious "new" foods - quinoa (tastes like rice), winged bean, amaranth, eelgrass, buffalo gourd
3. Must maintain genetic diversity of crop plants
• a. example - ancient potatoes in Peru
C. Eat lower on the food chain
• 1. Average individual in a developing country consumes 1 lb of grain each day (consumed directly as whole or milled cereal)

2. Average American consumes 5 lb of grain each day (20% consumed directly, about 80% fed to livestock that we then eat)
• a. If we ate grain directly, there would be more food in this county.

Facing the Future- a good site talking about history and enviromental impact
A review of 1996 world and U.S. population trends with links to WWW sites dealing with population questions
FAO: Food and Agriculture Organization
UN Human Development Programme
Population Reference Bureau
WorldWatch Institute
U.S. Census Bureau- World population information
1996 World Population Conference- highlights
Map showing food supply gap between rich and poor countries
U.S. Population Clock
Can we Sustain our Population with Agricultural Improvements?: An FAO Report
Population sites- Yahoo
 

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Last revised: Dec. 6, 2000 - Straney