EVR 1001 - Lecture 2

Human Population Dynamics

Overview

• Basic Concepts of Population Dynamics

• Analyzing and Estimating Future Population Growth

• Age Structure

• The Demographic Transition

• Longevity Effects on Population Growth

• Human Population Effects on the Earth

• Estimating Earth's Carrying Capacity

• Zero Population Growth Feasibility

Basic Concepts of Population Dynamics

• Population Dynamics: Study of population changes.

• Population: Group of individuals of the same species in the same area.

• Species: Interbreeding individuals; made up of populations.

• Demography: Statistical study of human populations.

Key Population Properties

• Five Key Properties:

  • Abundance

  • Birth rates

  • Death rates

  • Growth rates

  • Age structure

• Population data usually expressed as crude rates (per 1000 people), e.g., 2 births/1000 people/year.

Population Growth Types

• Exponential Growth: Constant increase by percentage per unit time.

  • Peak Growth: 2.1% (1965-1970), now 1.2% (slowing in developed nations).

  • U.S. growth rate = 0.6% (with immigration).

History of Human Population Growth

Growth Stages

• Stage 1: Hunter-gatherers; population < a few million.

• Stage 2: Agricultural rise; population 5 million (10,000 B.C.) to 100 million (A.D. 1).

• Stage 3: Industrial Revolution; population 900 million (1800) to 3 billion (1960).

• Stage 4: Current population over 8 billion.

Population Milestones

• 1 billion in 1800, 3 billion in 1960, 4 billion in 1975, 5 billion in 1987, 6 billion in 1999, 7 billion in 2011, 8 billion in 2022.

• Improvements in medicine, technology, sanitation, food production contributed to growth.

Future Population Growth Analysis

Growth and Doubling Time

• Doubling Time: Time to double population size, calculated with the Rule of 70.

  • E.g., U.S. (growth rate 0.6%) takes 117 years to double.

• Global population growth rate is currently 1-2% per year.

Growth Limits

• Exponential growth is temporary; leads to Logistic Growth with a carrying capacity.

• Vital statistic: Total Fertility Rate influences growth.

Social Influence on Fertility

• Factors Controlling Fertility:

  • Social factors: cultural/economic.

  • Technical factors: access to birth control.

• Increasing maternal age at first childbirth impacts growth rates.

Age Structure

Types of Age Structure

• Pyramid: Young population, high death rates.

• Inverted Pyramid: Large elderly population.

• Column: Low birth and death rates.

• Column with Bulge: Historical events impact birth/death rates.

Demographic Transition

Transition Model

• Three Stages:

  1. High birth/death rates.

  2. Death rates fall due to improved nutrition/health.

  3. Birth rates decline.

• Not uniform across countries; cultural and economic differences impact transition.

Longevity Effects

• Life Expectancy: Higher in developed nations (84.6 years in Japan vs. 45.9 years in Central Africa).

• Chronic vs. acute diseases affect mortality rates.

Human Population Effects on Earth

Environmental Impact

• Total impact formula: T = P x I (Impact = Population size x Individual impact).

• Modern technology increases resource use.

Carrying Capacity

• Depends on the quality of life considered acceptable.

• Various estimation methods including the packing problem and deep ecology viewpoints.

Future Projections

• Population growth increases challenges: food, water, energy demand rises significantly with increased population.

Zero Population Growth Possibilities

• Strategies to achieve ZPG include:

  • Delaying childbirth.

  • Access to birth control.

  • Educational initiatives and economic opportunities for women.

  • Policies to limit family size (e.g., China's One Child Policy).