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Announcements. Quiz on Friday January 14 th Extra Credit: Check Stern MASS website Each project is worth up to 0.5 pts added to a previous EXAM. Each student may do up to 2 (independently!!) Due January 21, 2011. Human Population. January 12, 2011. Declining Death Rates.
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Announcements • Quiz on Friday January 14th • Extra Credit: Check Stern MASS website • Each project is worth up to 0.5 pts added to a previous EXAM. • Each student may do up to 2 (independently!!) • Due January 21, 2011
Human Population January 12, 2011
Declining Death Rates • The dramatic increase in Earth’s human population in the last 200 years is because death rates have declined more rapidly than birth rates.
Why has death rate declined? • More people have access to: • Adequate food • Clean water • Safe sewage disposal
Life Expectancy • Def: The average number of years members of a population are likely to live
Infant Mortality • Life expectancy is most affected by infant mortality, the death rate of infants less than one years old. • Infant health is affected by the parents’ access to education, food, fuel, and clean water.
Life Expectancy • New threats arise as populations become denser. • AIDS and Tuberculosis are a concern in places where disease can spread quickly.
Demographic Transition • Def: A model that describes how economic and social changes affect population growth rates. • There are 4 stages of the transition
Stage 1: Preindustrial • Birth Rate: High • Death Rate: High • Population Size: Stable
Stage 2: Transitional • Population Explosion Occurs! • Death Rates: Decline (hygiene, water, food). • Birth Rates: Remains high
Stage 3: Industrial • Population growth slows. • Birth Rate: Decreases • Begins to match Death rate • Population size stabilizes
Stage 4: Postindustrial • Birth Rate: Drops below replacement level birth rate. • Population Size: Begins to decrease.
Using the Figure • What is happening to the birth rate and death rate when there is a rapid population growth? • What is happening to the birth and death rates when there is zero growth? • What is happening to the birth and death rates when population growth is negative?
Using the Figure • What is happening to the birth rate and death rate when there is a rapid population growth? • The birth rate is higher than the death rate • What is happening to the birth and death rates when there is zero growth? • They are about the same • What is happening to the birth and death rates when population growth is negative? • The birth rate is lower than the death rate.
Women and Fertility • Total Fertility Rate: • Developed Countries: 1.6 children per woman • Developing Countries: 3.1 children per woman
Changing Population Trends • A rapidly growing population uses resources at an increased rate and can overwhelm the infrastructure of a community. • Infrastructure: The basic facilities and services that support a community, such as schools and hospitals.
Sprawl • uses more land than necessary; • has a lower population density than traditional cities and towns (e.g., fewer people in larger houses); • creates a dependence on cars for almost everything; • results in fragmented open spaces, wide gaps between development, and a scattered appearance;
Sprawl • separates uses into distinct areas (so, you don't usually have a store or a movie theater within walking distance from your home); • is characterized by repetitive one-story commercial buildings surrounded by acres of parking; and.