Human PopulationsChapter 9

Studying Human Population

Human populations have grown faster in the 20th 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 communityPublic 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 areasLeads 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 identifiedQualify 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.