Human Populations Chapter 8, p

Current Population Humans are currently experiencing a phase of exponential growth (aka a J growth curve). Write this value down – World Population Clock Economist Thomas Malthus first proposed that there is a limit to the size of a population, and that when it is in exponential growth it will inevitably result in a crash. This would represent the loss of billions of lives A mild dip would be a loss of millions of lives

Think… Can the human population continue on its current trajectory? Why or why not? What are the limits to human population? What do you think the carrying capacity is? What are the implications to the planet if human population continues to grow “unchecked”?

Limits to Population Size Humans rely on food, water, shelter, space, and energy to survive. In some areas of the world, limits to one of these resources limits population size. As population increases more pressure is put on the environment for increased resources. MORE PEOPLE NEED MORE RESOURCES MORE MORE MORE!

Demographics The study of dynamics of population change. As populations expand, not only are we demanding more resources, we are creating more waste and degrading the environment. Human Development Index (HDI) is a measure of “well-being” of a country based on life expectancy, GDP, education, and standards of living. Typically, MEDCs have a higher HDI than LEDCs. 20% of world population is MEDC, 80% is LEDC

Measures of Pop Change Four main factors that affect population size are birth rate, death rate, immigration, and emmigration. Measured by Crude Birth Rate (CBR): number of births per thousand individuals in a population per year. Crude Death Rate (CDR): number of deaths per thousand individuals in a population per year. Birth or Death Rate divided by population size times 1,000 Natural Increase Rate (NIR): the rate increase as a percentage. This neglects the effects of migration (crude birth-crude death)/10 Doubling Rate: time in years for a population to double in size. An NIR of 1% will make a population double in 70 years Doubling = 70/NIR

Region Pop (10^6) Land Area (km^2 x 10^6) Births (10^6) Deaths (10^6) CBRCDRNIR Pop Density World Asia India Africa Tanzania Europe Switzerland N America USA

Region Pop (10^6) Land Area (km^2 x 10^6) Births (10^6) Deaths (10^6) CBRCDRNIR Pop Density World Asia India Africa Tanzania Europe Switzerland N America USA

Why do people have large families? 1.High infant and childhood mortality 2.Security in old age 3.Children are an economic asset in agricultural societies 4.Status of women 5.Unavailability of contraception How to reduce family size: 1.Provide education 2.Improve health 3.Provide contraception 4.Increase family income 5.Improve resource management

Population Pyramids Show how many individuals are alive in different age groups in a country for any given year. Population on x and age on y

Demographic Transition Model Describes the patters of decline in mortality and fertility nationally of a country as a result of social and economic development. Stages are: 1.Pre-Industrial Society: high birth, high infant mortality, large families, high death 2.LEDC: death drops as health and sanitation improve, lifespan increases, high birth, lowering infant mortality 3.Wealthier LEDC: birth rate continues to fall, population starts to level, family size decreases, low infant death 4.MEDC – low birth and death rates. Stable population. 5.MEDC – population may not be replaced as fertility rate is low. Problem of aging workforce.

Criticism This model is heavily criticized. Why? Not all countries follow this progression and some progress very rapidly. Thought to be too heavily European based. Suggests that all countries go through these stages, neglecting culture. The advent of large cities has also created slums with poor sanitation and health care. Assumes increase in education and contraception will decrease birth rates. Ignores religious and cultural practices. Eurocentric model, assumes all countries will become industrialized.