ENVIRON 102 Chapter Notes - Chapter 5: Logistic Function, Doubling Time, Reproductive Health
10 May 2018
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Chapter 5 Human Population Growth (all)
5.1 The History of Human Population Growth
Three Periods of Growth: Human populations experienced three periods of growth.
Demographers: people who study size, density, and distribution of human populations
Three periods of human population growth
o Pre-agricultural period
▪ Period of global migration
▪ Gradual growth over 1 million years
▪ Tool-making, communication, development of human culture
▪ 5-10 million people
o Agricultural period
▪ 5000 BC – 1700 AD
▪ Domestication of plants and animals, development of farming
▪ Irrigation, plowing
▪ 500 million
o Industrial period
▪ Advent of Industrial Revolution at around 1800
▪ Technologies powered by fossil fuels
▪ Improved sanitation, medicine
▪ More than 6.7 billion people
Demographic Transition Model: Demographic transition model describes 4 stages of change in human
population growth.
1929 Warren Thompson, demographer, published Population
o Economic development increases overall well-being and also decreases birth rate
o Findings were translated into the demographic transition model (describes four stages in
human population growth)
Demographic transition model
o Stage 1: Pre-transition
▪ Prior to economic development
▪ Low food availability, disease, high death rates among young, high birth rates
o Stage 2: Mortality transition
▪ Relieved food shortages, better living conditions and health care, access to
education, death rate decreases, birth rate remains/increase
▪ Ex: Afghanistan, Niger
o Stage 3: Fertility transition
▪ Continued economic development social and cultural changes lower birth
rates delay in starting families lower total fertility rates
o Stage 4: Stability transition
▪ Low birth rate and low death rate
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▪ Birth rate is nearly equal to death rate
▪ Characterized by zero population growth or even a decline in population
Latin America: Case Study on Demographic Transition
Stage 1: 1600-1900 European colonization
o Most families lived on farms
o Poor, malnourished, short life expectancy
Stage 2: mortality transition probably began around 1900
o More people moving into cities
o Death rate declined rapidly but birth rate only declined slightly population growth rate
increased
Stage 3: fertility transition by 1970
o Improvement in overall well-being – increase in personal wealth, access to clean water,
lower incidence of infectious disease, rise in literacy
o Drastic decrease in birth rate and decline in population growth rate
o Increase in median age
Stage 4: stability transition by 2050
o Continued decline in birth rate
o Increase in median age
o Increase in death rate and decrease in population growth rate
5.2 Global Variation in Human Population Growth
Birth Rate: Wealth and age influence birth rates.
Birth rate: number of babies born each year expressed as a percent of the population
Worldwide, birth rate is decreasing
Poor countries have high birth rates (3-5%)
Wealthy countries have low birth rates (0.8-1.5%)
Difference in birth rate is because of age of child-rearing
o Women in poor countries have children at a young age
Age-specific birth rates: number of children born in a year per 1000 women within defined age
groups
o Describes age-related variation in birth rates for an entire population
o When age-specific birth rates are high, the time between successive generations shorten
more children growing up and having children high population growth rate
Age-specific fertility rates: number of children born each year to an average female within an age
class
o Ex: Ethiopia has TFR of 6.1 (Ethiopian women who survive their full childbearing period
will bear an average of 6.1 children)
o Calculated under the improbable assumption that all women within a population live
through their reproductive years (ages 15-49)
o This is improbable for poor countries because of infectious diseases and shitty medical care
o Even though Ethiopia has TFR of 6.1, actual average number of children born to women
ages 15 to 49 was only 4.8
Death Rate: Wealth and age also influence death rates.
Death rate: percent of individuals in a population that die each year
Correlates to economic development, or more specifically, nutrition, sanitation, and health care
Component of death rates in poor countries – infant mortality rate
o Infant mortality rate: percent of infants within a population who die before age 1
o Influenced by sanitation, water quality, and availability of health care before/after birth
o Infant mortality rates are 18 times higher in poor countries than in wealthy countries
o Can be expressed in terms of survivorship
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
Three periods of growth: human populations experienced three periods of growth. Demographers: people who study size, density, and distribution of human populations. Three periods of human population growth: pre-agricultural period, period of global migration, gradual growth over 1 million years, tool-making, communication, development of human culture, 5-10 million people, domestication of plants and animals, development of farming, 500 million. Irrigation, plowing: agricultural period, 5000 bc 1700 ad, industrial period, advent of industrial revolution at around 1800, technologies powered by fossil fuels, more than 6. 7 billion people. Demographic transition model: demographic transition model describes 4 stages of change in human population growth. 1929 warren thompson, demographer, published population: economic development increases overall well-being and also decreases birth rate, findings were translated into the demographic transition model (describes four stages in human population growth) Stage 1: 1600-1900 european colonization: most families lived on farms, poor, malnourished, short life expectancy.
