APES 3.6 Age Structure

Why has the human population begun increasing?

1. Increased agricultural productivity

2. Improved sanitation and waste treatment

What sociocultural factors influence human populations?

• Economic health

• Geopolitical conflicts

• Healthcare

• Education

• Birth control

Demographer

Scientist in the field of demography that:

• Studies population trends through size, fertility, life expectancy, and migration

• Offer insight into why population changes and how humans influence those changes

Crude Birth Rate

# of births / 1000 individuals per year

Crude Death Rate

# of deaths / 1000 individuals per year

Global Population Growth Rate

(CBR - CDR) / 10

• Written as %

Net Migration

• Positive Net Migration: More immigrants than emigrants

• Negative Net Migration: More emigrants than immigrants

National Population % Growth Rate Equation

[(CBR + Immigrants) - (CDR + Emigrants)] / 10

• Inputs - Outputs

Life Expectancy

Average # of years an infant born in a particular country and year is expected to live

• High expectancy: More developed nation

  • access to health care

  • better living conditions

  • consumerism

  • environmental impact

Disease

Substantial regulators of human populations

1. Heart Disease: Leading diseases in developed nations

2. Infectious Diseases: Leading diseases in developing nations

HIV

Virus that attacks immune system

AIDS

Condition caused by HIV where immune system becomes severely weakened

Age Structure Diagram / Population Pyramid

Shows distribution of ages in a certain population based on sex

• x-axis: Each side = male or female + population size or %

• y-axis (Center): Age groups based on female reproductive ability

  • Pre-reproductive: 0-14 yrs Tend to not bear children

  • Reproductive: 15-45 yrs Can bear children

  • Post-reproductive: 46+ yrs Declining fertility

• Shows future pop changes

Majority Pre-Reproductive (Bottom-Heavy)

Population grows quickly

• ~Developing Nation

• High CBR/CDR

• Reproducing longer

• Agricultural economy: Young workforce

  • ex. India, Brazil, Nigeria, Mexico

Majority Reproductive (Middle-Heavy)

Stable population growth

• Wealthy nation

• Industrial economy

• Reproduce later: women’s rights + education = reduced fertility rates

• Relatively even age groups + CBR/CDR

  • ex. US, Canada, Australia, Sweden

Majority Post-Reproductive (Top Heavy)

Declining population

• Economically/Socially developed / Highly educated

• Long-term social services

• Little reproductive women to replace aging population

  • ex. Germany, Japan, Italy, Russia