Soc Notes Week 16 - Population and Ecology

COS: 11.) Contrast population patterns using the birth rate, death rate, migration rate, and dependency rate: Identifying the impact of urbanization. Describing the depletion of natural resources. Projecting future population patterns.

Population and Ecology

1.      Demography: the study of the size and makeup of the human population and how it changes.

2.      Collecting Data: demographers use many different statistics in their work: Census / birth records / death records / family lineages / migration rates

3.      Census: a count of the population, usually with a record of the age and sex of its members. / Mary and Joseph with Roman census / 1790 –first US census

4.      Local census: often completed every year / more accurate / usually based on sampling

5.      Vital statistics: records of births, deaths and their causes, marriages, divorces, some diseases, and similar data are recorded in each state and reported to the National Center for Health Statistics.

6.      Variables that can cause the size of the population in a given region to change: births, deaths, migrations

7.      Fertility: a measure of the rate at which people are born

8.      Mortality: a measure of the rate at which people die

9.      Migration: the movement of people into or out of a geographical area.


1.      Fertility data indicate the rate at which babies are born.

2.      The crude birth rate is the number of births per 1000 population

3.      To more accurately predict how many babies will actually be born, more information is needed: age-sex composition of the society, the number of males and females in the population, along with their ages.

4.      Soviet Union: there was an imbalance in because of men killed during WWI, Civil War of 1917-21, WWII, repressive era following WWII.

5.      Most demographers assume women are fertile from 15 to 49

6.      Fecundity: an individual woman’s potential for bearing children (women can potentially have 20-25 children)

7.      Fertility varies among societies and subcultures

8.      The number of children born in a society is affected by: wealth, environment, societal norms about marriage and children (richer nations have lower birth rates and poorer nations have higher birth rates / upper class usually have lower birth rates than the poorer classes / rural women typically have more than urban women / children are expensive / societal norms for age of marriage / separation by war, working away from home, spousal conflicts, Niddah – Jewish)


1.      Mortality: The rate of death in a population

2.      Crude death rate: number of deaths per 1000 / does not provide enough information to predict how many people will die or to compare death rates among populations

3.      For a more accurate estimate of the death rate, demographers consider age and gender.

4.      A population with many old people will have a higher death rate than a comparatively young population / a population with many women will live longer than one with men

5.      Age-adjusted death rate: a measure of the number of deaths at each age for each sex, usually per 100,000 living at that age / Demographers can also compute life expectancy by predicting how many of each age cohort, or age group, will die at each age.

6.      Mortality, life fertility, varies with wealth

7.      When people, especially infants, have adequate food, housing, and medical car, they are less likely to die of disease, etc.

8.      Infant mortality: death in the first year of life

9.      Death rates vary among class, wealth, race


1.      Includes both immigration and emigration

2.      Immigration: movement into an area

3.      Emigration: movement out of an area

4.      Much more difficult to measure than birth or death rates. To be considered at migrant, how far must a person move, and how long should the person remain in the new place?

5.      In the United States, moving within a county is not considered migration, but moving from one county to another is.

6.      Migrant workers: those who travel around the country doing farm labor are not technically considered migrants because rather than remaining in a new location after the work season is over, they return to their original starting point and take up jobs in that area.

7.      Why do people move? Demographers speak in terms of Push and Pull factors.

8.      Push factor: those that push people away from their homes: famines, wars, political oppression, loss of jobs, bad climate

9.      Pull factor: those that make a new place seem more inviting: the chance to acquire land or jobs, the discovery of riches such as gold or oil, or the chance to live in a more desirable climate

10.  Ex: Eastern Europeans moved to west for jobs / California Gold Rush / Prehistoric times / food for tribes

11.  Immigration Laws of US – 1921 and 1924 / 10-20 million Africans brought to Western Hemisphere between 1619 – 1808

Population Trends and Life Experiences

1.      Population pyramid: a graph that shows how many males and females from different catagories.



4.      Canada 2010


6.      Trends in population: Baby Boomers / Baby Busters / Gen X

7.      Why important: number of schools, social services / military / job prospects / college prospect / marriage rates (women born during the baby boom were more likely to marry at an older age or to stay single than those of earlier generations)

8.      Marriage squeeze: women traditionally marry older men, and if there is a shortage of older men for these women to marry, then a marriage squeeze occurs. (women born after baby boom have many older men to marry, so they may marry at a younger age; however, men born late in the baby boom who want to follow the normative practice of marrying younger women face a shortage)

9.      Population trends also affect clothing styles and fashions (Marilyn Monroe vs Olson Twins / Older women vs adolescents / low cut jeans vs stretch blue jeans with elastic waist / health club business / ski resorts / golf

10.  Housing costs are also affected by population trends (retirement homes)

11.  Government policies are affected (Social Security and Medicare)

The World population Explosion and the Demographic Transition

1.      Until about 200 years ago, both birth and death rates were very high. As a result, the size of the world population remained stable. For every person who was born, some died. Then a dramatic change occurred. First, in industrial nations in the early part of the 19th century the death rate dropped because of improvements in sanitation and nutrition. Second, birth rate moved up. This is referred to as the “population explosion”

2.      Demographic Transition: The change from high birth and death rates to low birth and death rates with a period of rapid population growth in between; this transition occurs as a society evolves from a traditional premodern stage to a modern industrial stage.

3.      It took the human race from the beginning of history until 1850 to reach a population of 1 billion people. It only took an additional 100 years to reach 2 billion, and only 35 years to reach 4.8 billion

Population Density

1.      Population density: where and how people are scattered across physical location

2.      United States has relatively low population density (in some remote areas, the density is only 5 people per square mile. In major cities, the density is as high as 100,000 per square mile. For the entire US the density is 68 people per square mile) (1992 World Almanac)

3.      France is 262 people per square mile(1992 World Almanac)

4.      Belgium is 842 people per square mile(1992 World Almanac)

5.      Japan is 840 people per square mile(1992 World Almanac)

6.      Netherlands is the most densely populated country in Europe with 931 people per square mile

7.      China is the largest nation in the world, and has a population of over 1 billion people has a population density of 306 people per square mile. (1992 World Almanac)

8.      Bangladesh, the most densely populated country in the world has 2028 people per square mile in 1985(1992 World Almanac)

Population Ecology

1.      Ecology: the study of the interrelationships between living organisms and the environment

2.      How many people can the world contain?

3.      Thomas Robert Malthus (1766 – 1834) argued in his Essay on the Principle of Population that because of the strong attraction between the two sexes, the population could increase by multiples, doubling every 25 years.

4.      Malthusian theory: the population would increase much more rapidly that the food supply. The population would increase in a geometric progression (2,4,8,16,32…) while the food supply would increase in an arithmetical progression (1,2,3,4,5,6…). Malthus contended that the population would eventually grow so large that food production would be insufficient, and famine and crowding would cause widespread suffering and would increase the death rate. He suggested that the birth rate be decreased, especially through postponing marriage to a later age.

5.      John Stuart Mill and John Maynard Keynes supported the Malthusian theory.

6.      Karl Marx argued against it, contending that starvation was the caused by unequal distribution of the wealth and its accumulation by capitalists.

7.      Neo-Malthusian theory: as food production techniques increased rapidly (technology) the theory was revised; included more information, such as taking into account the effects of technology, but still predicting that population cannot grow indefinitely without dire consequences

Population and Other Natural Resources

1.      Greenhouse effect

2.      Chlorofluorocarbons

3.      Sulfur emissions

4.      Styrofoam / polystyrene foam

5.      Reduce / Reuse / Recycle

Zero Population Growth

1.      This is the goal of current world population policy.

2.      Achieved when parents have only 2 children: replacement only

Notes based on: Sociology- an introduction, 4th edition, by Eshleman, Cashion, and Basirico. Harper Collins. 1993