1. Demography: study of populations (human)
Factors that affect population growth (economics & social structure)
Developed Countries: higher avg. incomes, slower population growth ,diverse industrial economies, stronger social support systems.
Developing Countries: lower avg. incomes, simple /agricultural-based economies, rapid population growth

2. Human Population Growth
Has accelerated exponentially over the last few centuries.
Mainly due to: a) better hygiene b) increases in food production
Thanks to the industrial and scientific revolution

3. Data Used to Predict Population Size
1. Age Structure – distribution of ages in a specific population at a certain time
graphed in a population pyramid (two bar-graphs flipped on their sides, back to back)
More young people than old people = high rates of growth
even distribution of ages = slow or no growth

4. Data Used to Predict Population Size
2. Survivorship Curve: how much of a population survives to a given age
Type I: most members survive to be very old (wealthy nations like Japan and Germany)
Type II: similar death rate at all ages
Type III: many children die (very poor populations)
I & III may remain the same size or grow slowly

5. Data Used to Predict Population Size
3. Fertility Rates: # of babies born each year per 1,000 women in a population
Total Fertility Rate: avg. # of babies a woman gives birth to in her lifetime
Replacement Level: # of children each parent must have in order to “replace” themselves in the population (2.1 or slightly more than 2 because not all children born will survive and reproduce)

6. Fertility Rates in the U.S.

7. Data Used to Predict Population Size
4. Migration: movement of individuals between areas
immigration = in
emigration = out
the populations of many developed countries might be decreasing if not for immigration

8. Declining Death Rates Large impact on population growth
Thanks to adequate food, clean water, safe sewage disposal, vaccines
Life Expectancy: avg. # of years a person is likely to live
Most affected by infant mortality (death rate of infants less than a year old)
Expensive medical care is not needed to prevent it (rates vary greatly between countries w/ similar income)
Mainly affected by parents’ access to education, food, fuel, and clean water
Babies have a good chance of surviving if they are well fed, kept clean and warm
New Threats to life expectancy (arise as populations become denser): ex. AIDS, tuberculosis

10. The Demographic Transition (stages that countries progress through)
Stage 1 – Preindustrial: birth rate & death rate high, population size stable
Stage 2 – Transitional: death rates decline (hygiene, nutrition, education improve), birth rates remain high, population grows VERY fast
Stage 3 – Industrial: birth rates decreases (becomes closer to the death rate), population growth slows and stabilizes
Stage 4 – Postindustrial: birth rate drops below replacement level, population begins to decrease

12. Women and Fertility Decreased birth rates are mainly due to:
Increased levels of education in women (educated women find that they do not need to bear as many children to ensure some will survive, many learn family planning techniques)
Economic independence for women (able to contribute to family’s increasing prosperity)

13. 9-2 Changing Population Trends
Infrastructure: the basic facilities and services that support a community (public water supplies, sewer lines, power plants, roads, subways, schools, hospitals)
Growing populations can overwhelm infrastructure (ex. suburban sprawl, overcrowded schools, polluted rivers, barren land, inadequate housing)

14. 1. A Shortage of Fuelwood 2. Unsafe Water
Problems of Rapid Growth: When a growing population uses resources faster than they can be renewed – the following are most affected:
1. A Shortage of Fuelwood
as populations grow deadwood does not accumulate fast enough and living trees are cut down
boiling water and cooking food helps eliminate disease and malnutrition
2. Unsafe Water
w/o infrastructure many places use local water supply for drinking and washing, and also for sewage disposal (breeding ground for dysentery, typhoid, and cholera)

15. urbanization: more people are living in cities than in rural areas
3. Impacts on Land
Arable Land: land that can be used to grow crops (often not enough for growing populations)
competing uses for land leads to tradeoffs (agriculture, housing, natural habitats)
urbanization: more people are living in cities than in rural areas
housing w/in cities becomes more costly, more dense, in shorter supply
suburban sprawl – leads to: traffic jams, inadequate infrastructure, the reduction of land for farms, ranches, wildlife habitat

16. Least Developed Countries – show few signs of development, in some cases have increasing death rates, while birth rates remain high – often given priority for foreign and development programs
Managing Development and Population Growth
Some countries attempt to reduce birth rates directly through public advertising, family planning programs, economic incentives, or legal punishments for their citizens.

17. Growth is Slowing Worldwide growth rate peaked in the late 80’s
Fertility rates have decreased since the early 70’s
Growth is predicted to slow in this century
World-wide population projections predict a growth to 9 billion by Economic or political changes could lead to higher or lower numbers.