Studying Human Populations Chapter 9

Demography Demography is the study of populations, but most often refers to the study of human populations. Developed countries have higher average incomes, slower population growth, diverse industrial economies, and stronger social support systems. Developing countries have lower average incomes, simple and agriculture-based economies, and rapid population growth.

Warm-up questions In the United States, most parents have two or three children. Fifty years ago, many parents had six or more children. What might have caused the change? What problems can occur if an area’s human population grow very rapidly?

Human Population over time Why do you think the population has recently grown so rapidly?

Reasons for increase in population growth Increase in food production Improvement in hygiene that came up with industrial and scientific revolutions. Increase in literacy level. Any other reason?

Age-Structure diagrams

Did you see this in the population pyramid? Countries that have high rates of growth usually have more young people than older people. Countries that have slow growth or no growth usually have an even distribution of ages in the population. When parents are having fewer children the population will have fewer young people.

Survivorship Mammals such as humans that produce few offspring with good parental care exhibit Type I survivorship with low death rates during early and middle life. Organisms such as oysters that produce numerous offspring with little or no care exhibit Type III survivorship with high death rates of young. Type II curves are intermediate, with a constant death rate over the organism’s life span.

Video on Survivorship curve

Give reasons Japan and Germany currently have a Type I survivorship curve. Type III survivorship is the pattern in very poor human population.

The baby boom and baby bust cycle

Definitions Fertility rate: the number of babies born each year per 1,000 women in a population is called the fertility rate or the average number of children a woman give birth to in her lifetime. Replacement level: the average number of children each parent must have in order to “replace” themselves in the population. What would that number be?

Migration The movement of individuals between areas is called migration. Immigration is a factor which results in increase in population.

Declining Death Rates Access to adequate food, clean water, and safe sewage disposal. Discovery of vaccines. Better health care ---?

Life expectancy Life expectancy has reduced in Sub-Saharan Africa in recent decades. Give reason

The Demographic Transition

Contd.. First Stage: Preindustrial condition. The birth rate and the death rate are both at high levels and the population size is stable. Second Stage: Population explosion occurs. Death rates decline, but the birth rate remains high. Third stage: birth rate decreases. Population size stabilizes. Fourth stage: the birth rate drops below replacement level, so the size of population begins to decrease.

Women and fertility Increasing education and economic independence for women (relate this to decrease in birth rate). In developed countries total fertility rate is 1.6 children per woman while in developing countries, the rate is about 3.1 children per women.