Human Populations Chapter 9

Studying Human Population Human populations have grown faster in the 20 th century than it ever has before. Demography: the study of populations, usually human populations.  Study history of population growth: the makeup, the size, economy at the time, and social structure.  Separate developing countries and developed countries.

Human Population over Time During the 1800s the human population grew exponentially  Grew due to improvements in food production and hygiene that came with industrial and scientific revolution  It is unlikely the earth can sustain such a rapid growth

Forecasting Population Size Demographers look at properties of populations to predict what a community will face in the coming years.  Age Structure: the distribution of ages in a specific populations at a certain time.

Forecasting Population Size Survivorship: the percentage of members of a group that are likely to survive to a given age.  Wealthy developed countries have a higher survivorship than developing countries

Forecasting Population Size Migration: the movement of individuals between areas.  Immigration: movement into an area  Emigration: movement out of area  Populations of many developing countries might be decreasing if not for immigration.

Forecasting Population Size Fertility Rates: number of babies born each year per 1,000 in a population.  Total fertility rate is the average number of children a women gives birth to in her lifetime

Declining Death Rate One of the reasons for rapid population growth is due to the fact that death rates have declined more than birth rates.  Declined because people have access to adequate food, clean water and safe sewage disposal.  Life Expectancy: average number of years a person is likely to live Men: 74 years (born today) Women: 79 years (born today) Life expectancy changes as you get older and depends on a number of other factors.

Declining Death Rate Life expectancy is most affected by infant mortality: the death rate of infants less that a year old.  In 1900 worldwide life expectancy was 40 years and the infant mortality was very high.  By 2000 the infant mortality was one-third of the 1900 rate.  Infant death is most affected by the parents access to education, food, fuel, and clean water. In developing countries diseases such as AIDS and tuberculosis have affected the life expectancy.

Women and Fertility Decline in birth rate is directly correlated to the education and independence of women  Educated women find that they do not need to have more children to ensure that some will survive.  The total fertility rate in developed countries is 1.6 children per woman, while in developing countries it is 3.1 children per woman

Changing Populations Trends A rapidly growing population uses resources at an increased rate and can overwhelm the infrastructure of a community  Infrastructure: the basic facilities and services that support a community Public water supplies, sewer lines, power plants, roads, subways, schools, and hospital. Symptoms of overwhelming populations growth include suburban sprawl, overcrowded schools, polluted rivers, barren land and inadequate housing

Problems of Rapid Growth A rapidly growing population can use resources faster than the environment can renew them, unless resources come from elsewhere. Vegetation, water and land are the resources most critically affected by rapid growth

Problems of Rapid Growth Shortage of Fuelwood – wood is the main fuel source in many developing countries. Unsafe Water – in places that lack infrastructure, the local water supply is used for drinking and washing but also for sewage  Many diseases are carried in water supplies

Problems with Rapid Growth Impacts on the Land –  Arable land: land that can be used to grow crops  Urbanization: more people are living in cities than in rural areas Leads to suburban sprawl

A demographically diverse world More developed countries vs. less developed countries vs. least developed countries  Least: countries show few signs of development and in some cases have increasing death rates, while birth rates remain high United Nations identified Qualify for foreign aid and development programs

World Population Distribution

World population and density

The World at Night

Growth is Slowing Fertility rates have declined since about 1970 in both developed and less developed regions.