Human Population

Human Population

Overview

Understanding how human populations change is important because it affects society, the economy, and the environment.

Focus Question

What factors affect human population growth?

New Vocabulary

  • Demography: The study of populations, including their size and trends.

  • Demographic Transition: The change from high birth and death rates to lower rates as a country develops.

  • Zero Population Growth (ZPG): A situation where the number of births and immigrants equals the number of deaths and emigrants, meaning the population does not grow.

  • Age Structure: The breakdown of people of different ages in a population.

Review Vocabulary

  • Carrying Capacity: The largest number of people an environment can support over a long time.

Human Population Growth

Demography looks at human population size, where people live, movement patterns, and birth and death rates.

Factors Affecting Human Population Growth

  • Technological Advances: Innovations that have increased the carrying capacity include:

    • Agriculture: Better farming methods and crops.

    • Domestication of Animals: Provided steady food and labor.

    • Medicine: Improved healthcare leading to fewer deaths.

    • Improvements to Shelter: Better living conditions help people live longer and have more children.

Historical Population Trends

  • From early civilizations to the Industrial Revolution, the population increased due to farming advancements.

  • The Bubonic Plague (1347-1350) caused a major population drop.

  • The Industrial Revolution saw rapid population growth.

Current Population Statistics

  • The human population keeps growing, but the rate of growth is slowing down.

  • Future growth rates are expected to stabilize.

Trends in Human Population Growth

  • Economic conditions often affect population growth trends.

  • The demographic transition shows how birth and death rates change in societies.

  • Population Growth Rates (PGR) help compare different countries’ population changes.

Zero Population Growth (ZPG)

  • ZPG occurs when the equation (Births + Immigration) = (Deaths + Emigration) is balanced.

  • At ZPG, the age structure should show a mix of all age groups.

Age Structure

A population's age can be divided into three groups:

  • Pre-Reproductive Stage: Ages 0-14.

  • Reproductive Stage: Ages 15-44.

  • Post-Reproductive Stage: Ages 45 and older.

Examples of Age Structure (2015):

  • Kenya: Younger population.

  • United States & Germany: Older, more balanced populations.

Concerns About Carrying Capacity

Scientists worry the human population may exceed what the Earth can support.

  • Resource Utilization: The amount of resources each person uses is important.

Projected Population (2050)

Predictions for populations in developed countries vary:

  • Estimates range from 7.3 billion to 10.5 billion, depending on various factors affecting growth.

Quiz Questions Recap

  • For Zero Population Growth, a balanced age structure is important.

  • In ZPG, births plus immigration should equal deaths plus emigration.