1. Unit 2-2a
Human Populations

2. Studying Human Population
Demography – The study of human populations
The history of our human population was fairly stable until the 1800s when humans experienced…
Exponential Growth – A growth rate that continues to increase each year
Demographers predict a world population of 8 billion by the year 2025.

3. Forecasting Populations
Four factors affect population predictions…
Age Structure – The distribution of age in a population
Countries with high growth rates have more young people than old people.
Countries with slow
growth rates have even
distribution of ages

4. Forecasting Populations
2. Survivorship – Percentage of a population that are expected to survive a certain age.
Wealthy developed countries such as Japan and Germany currently have a Type I survivorship curve because most people live to be very old.
Type II populations have a similar death rate at all ages
-Type III survivorship is the pattern in very poor human populations in which many children die.

5. Forecasting Populations
3. Fertility Rates – The number of babies born per 1,000 women. It’s an average.
Most countries have a fertility rate less than 3.
4. Migration – is any movement of individuals or populations from one location to another.
Movement into an area is immigration and movement out of an area is emigration.

6. More successful births and less deaths = larger population
Death Rate Decreasing
Recently, life expectancies (the average age a person dies) has increased dramatically due to…
Medicine
More Food
Clean Water
Safe Waste Disposal
The average lifespan has increased to more than
70 years for many developed countries.
More successful births and less deaths = larger population

7. Why Human Populations Are Different!
Demographic Transition – A theory that describes a pattern of demographic change from high birth and death rates to low birth and death rates, and observed in the history of more-developed countries.
It occurs in 4 stages:
Stage 1 Population is low; Birth & death rates are high
Stage 2 Because of education, Births stabilize and death rates decrease as the population grows
Stage 3 Large population; Low birth and death rates
Stage 4 Population begins to decrease

8. Stages of Transition

9. Decreasing Birth Rates
The factors most clearly related to a decline in birth rates are:
Increasing education and economic independence for women
Educated women find that they do not need to bear as many children to ensure that some will survive.
Women are able to contribute to their family’s increasing prosperity and can spend less energy bearing children.
In modern society both parents are more likely to work away from home making child care child care, a financial burden.

10. Effects of Human Population Trends
Unit 2-2b
Effects of Human Population Trends

11. Problems with rapid growth
A rapidly growing population uses resources at an increased rate and can overwhelm the infrastructure of a community.
Infrastructure is the basic facilities of a country or region, such as roads, bridges, sewers, power plants, subways, schools, and hospitals.

12. A rapidly growing population can use resources faster than the environment can renew them.
Symptoms of overwhelming populations include suburban sprawl, polluted rivers, barren land, inadequate housing, and overcrowded schools.

13. Effects on Resources
In many of the poorest countries, wood is the main fuel source specifically for boiling water and cooking food.
When populations grow rapidly, people cut down living trees at a rapid rate, which reduces the amount of wood available in each new year.
As a result, many people suffer from disease and malnutrition because water is unsafe to drink and food cannot be cooked.

15. Unsafe Water
In places that lack infrastructure, the local water supply may be used not only for drinking and washing but also for sewage disposal.
As a result, the water supply becomes a breeding ground diseases such as dysentery, typhoid, and cholera.
Many cities have populations that are doubling every 15 years, and water systems cannot be expanded fast enough to keep up with this growth.

16. Impacts on Land
Growing populations may have a shortage of arable land.
Arable land is farmland that can be used to grow crops.
Growing populations compete for land use such as for agriculture, housing, or natural habitats.

17. Urbanization is an increase in the ratio or density of people living in urban areas rather than in rural areas.
People often find work in the cities but move into suburban areas around the cities.
This suburban sprawl leads to traffic jams, inadequate infrastructure, and reduction of land for farms, ranches, and wildlife habitats.

18. A Demographically Diverse World
Least developed countries are countries that have been identified by the united Nations as showing the fewest signs of development in terms of income, human resources, and economic diversity.
Populations are still growing rapidly in less developed countries.

20. Managing Development and Population Growth
Today, less developed countries face the likelihood that continued population growth will prevent them from imitating the development of the world’s economic leaders.
Many countries favor stabilizing population growth through investments in development, especially through improvements in women’s status.

21. In 1994, the United Nations held the International Conference on Population and Development (ICPD), to discuss relationships between population, development, and the environment.