Human Populations

Human Population Growth & Dynamics

• Global population exceeds $6\text{ billion}$, having doubled in the past $50\text{ years}$ due to agricultural and industrial developments.

• Population size is determined by the balance of birth/death rates and migration (immigration vs. emigration).

Quantitative Population Calculations

• $\text{Population Growth} = (\text{births} + \text{immigration}) - (\text{deaths} + \text{emigration})$

• $\text{Percentage Population Growth Rate} = \frac{\text{population change during period}}{\text{population at start of period}} \times 100$

• $\text{Birth Rate} = \frac{\text{births per year}}{\text{total population}} \times 1000$

• $\text{Death Rate} = \frac{\text{deaths per year}}{\text{total population}} \times 1000$

Factors Influencing Birth and Death Rates

• Birth Rates: Influenced by economic status (higher income leads to lower birth rates), cultural/religious background, social standing, birth control availability, and political/education policies.

• Death Rates: Influenced by age profile, life expectancy, food supply, safe drinking water/sanitation, medical care, natural disasters, and war.

Population Structure and Demographic Transition

• Demographic Transition: Occurs as life expectancy increases and birth rates fall.

• Population Pyramids:

  • Stable: Population size remains unchanged.

  • Increasing: High birth rate (wide base).

  • Decreasing: Low birth and death rates (wider apex).

Questions & Application Answers

• Question 1: a) Stage $3$, b) Stage $1$, c) Stage $2$, d) Stage $1$, e) Stage $4$.

• Question 2:

  • Pyramid A (Stage $4$): Low birth and death rates (narrow base, vertical sides, high survival beyond $65$ years).

  • Pyramid B (Stage $2$): High birth rate, falling death rate (wide base, sloping sides, lower survival beyond $65$ years).