The Human Population Chapter 9

Demography The study of populations. By studying the historical size and makeup of a population they can make predictions about future population size. They also group populations sizes with respect to economics and social structure, categorizing them into two groups: developed and developing. Why? Because they have similar population trends.

Human population over time: Population started to grow rapidly after Increased food production Improvements in sanitation Vaccines (small pox developed in 1796)

Forecasting Population Size Making age structure diagrams allows communitie s to predict how many schools, retirement homes, etc. they may need in the future.

Survivorship curves The percentage of members of a group likely to survive to a certain age.

Fertility rate The number of babies born per year per 1000 women. (OR) The average number of babies born per woman in her lifetime. Because this is an average, it can come out to be a decimal number…fertility rate in the US is currently 2.1 children per woman.

Replacement Level Fertility Number of babies born (along with any migration patterns) so that the total population neither grows or shrinks. Usually said to be 2. Why? Because 2 children would replace 2 parents.

Death rates Death rates have declined world wide. Adequate food supplies Clean water Safe sewage disposal Better health care Life expectancy has increased! Population increases.

The Demographic transition

CHANGING POPULATION TRENDS Lesson 9.2

Problems of growing populations: Use of resources at an increased rate: Can overwhelm infrastructure: Sewer lines, water supplies, power plants, roads, subways, schools, hospitals, roads. Can lead to overuse of natural resources: Soil becomes depleted of nutrients. Pollution increases. Deforestation Standards of living can decrease when there is not enough to go around.

Declining standards of living: Shortage of fuel wood: In poorer countries when populations are small, people will use fallen branches from trees as a fuel source. As populations increase, this is not enough and they start to cut live trees. This is the start of deforestation. Fuel woos also acts as a source of income: slash and burn.

Declining standards of living: Unsafe water In places that lack infrastructure, people may use the same water source for drinking, bathing, and sewage disposal. Dysentery, cholera, typhoid. Over 1 billion people go without a clean source of drinking water. That equates to 1/7 of Earth’s population.

Declining standards of living: Impacts on Land Competing uses of land Agriculture, housing, natural habitat Lack of arable land (land that can be used for agriculture). Increased urbanization. People are moving to the cities where they can find work. Larger infrastructure needed. Housing becomes more expensive.

Developed vs. developing? Demographers actually prefer to categorize populations into more and less developed because the reality of development is actually more complex. These least developed countries are actually the focus of the international community. High death, high birth rates, highest population growth.

Population Growth vs. development Lesser developed countries have actually tried to move forward in the demographic transition by starting political campaigns to lower birth rates. China, India, Thailand How? Political advertising, family planning, economic incentives, legal punishments.