Chapter 2: Population

Distribution-geographers are concerned about the arrangement of features on the earth’s surface. 3 main properties of distribution are: – Density-the frequency that something occurs in a given space. – Concentration-changes in distribution-how close together-dispersed or clustered. – Pattern-the arrangement of the distribution of features in a given space.

Population Demographics is the study of human population distribution and migration. Key Issues of Demographics are: – Food Supply – Health and life expectancy – Status of women – Migration

People are NOT distributed evenly across the Earth. Population is clustered in the mid latitude climates and relatively sparse in the dry and polar climates or the highlands.

Distribution- ¾ of the world’s population lives on only 5% of the land. Very uneven distribution was intensified in the 20 th cent. as population soared. 2/3 of the pop. lives near an ocean or river. Carrying capacity-the number of people that can be supported in an area given the technology of production. Density-the measure of the number of people per square mile/kilometer, etc. – Arithmetic density-total number of people divided by the total land area. It is the most common statistic given. – Physiologic density-is the number of people per unit of arable (farmable) land.

Arithmetic World Population Density

Physiological density is the number of people per unit of arable land, which is land suitable for agriculture. Physiological density is a better measure than arithmetic density of the relationship between population and resources. Even physiological density can be misleading since it does not consider the productivity of the soil or the resources and expertise of the farmers.

Crude death rate-the number of deaths per 1,000 each year. Crude birth rate-the number of births per 1,000 each year. Natural increase (NIR)rate-the % by which a population grows in a year. Computed by subtracting the % of CBR- CDR. Total Fertility Rate (TFR) the number of children born to women of childbearing age-usually reported as a percentage. Dependency ratio-the number of people who are too young or too old to work compared to the number of people old enough to work.

In 1798 he published An Essay on the Principle of Population Malthus was the first to sound the alarm that the world’s population was expanding more rapidly than food production. He was the first to recognize exponential or geometric population growth. Today those who share his concerns are Neo- Malthusians Rev. Thomas Malthus

Demographic cycles of population growth – Stage 1 High Stationary Growth with high birth rates 40/1000 or higher and high death rates. – Stage 2 Early Expanding with high birth rates and declining death rates (birth 40s/death 20/1000) = rapid growth in pop. – Stage 3 Late Expanding with declining birth rates (30s) and low death rates (10) = still significant growth – Stage 4 Low Stationary has low birth rates and low death rates (birth 15 and death 10 or lower) SPL Stationary Population Level

The Demographic Transition

Second Agricultural Revolution and Industrial Revolution 18 th century gains in agricultural production: – Crop yields improved with better farming methods – New crops such as potatoes, turnips and alfalfa – Storage and distribution improved which alleviated famines and shortages. Industrial Revolution was also a factor: – Improved sanitation – Improved medical care – Disease prevention such as smallpox vaccine

Population Pyramids – Charts that show the percentages of each age group in the total population, divided by gender. For poorer countries, the chart is shaped like a pyramid. Infant mortality rates are high, life expectancy is shorter.

Population Pyramids- display a country’s population in a bar graph form. Each 5 year group with the youngest 0-4 years old at the base of the pyramid are called cohorts. Males are shown on the left side and females are shown on the right. A wide-based pyramid indicates a country in Stage 2 of the Demographic transition.

Population Pyramids Charts that show the percentages of each age group in the total population, divided by gender. For wealthier countries, the chart is shaped like a lopsided vase. Population is aging, TFRs are declining.

Four Patterns of Population Structure Each nation faces different problems due to a large base with many young or negative growth.

In poorer countries, Infant Mortality Rates are usually high, which is reflected in the pyramid shape.

In poorer countries, Life Expectancy is usually shorter, which is also reflected in the pyramid shape.

Affect of AIDS on population pyramid for South Africa. Predicted population for 2035, without and with AIDS. With AIDS, looks like a population “chimney.”

AIDS is leaving large numbers of AIDS orphans.

1995 Population Pyramids reflect the economic prosperity of Western Europe and the less developed countries of Sub-Saharan Africa. In the mid-1990s almost 50% of Africa’s population was under 15 years of age. By contrast the number of people 65 and older in Western Europe is 5 times that of sub-Saharan Africa.