ENS 201 Chapter 7, Spring 2008

Human Populations Chapter 7 Outline: • Population Growth  Human Population History  Limits to population growth - Opposing Views  The Role of Technology • Human Demography  Two Demographic Worlds • Future of Human Populations Population growth / Human Population History • Until the Middle Ages, human populations were held in check by diseases, famines and wars, and thus grew very slowly • It took:  All of human history to reach 1 billion (1804)  150 years to reach 3 billion (1960)  12 years to go from 5 to 6 billion • Human population tripled during the twentieth century • Will it do so in the 21st century? What if? • Factors that contributed to population growth:  Increased navigation skills and communication between nations  Agricultural development  Better sources of power  Better health care and hygiene Human Population History • Between 1348 & 1650: periodical eruption of the plague that swept across Europe killed 1/3 of the European population • Beginning of the 20th century: an influenza virus (Spanish flue virus) killed 50 million persons worldwide Limits to Population Growth: Thomas Malthus View (1798) • Human populations tend to increase exponentially while food production is either stable or increases only slowly • Humans inevitably outstrip food supply and eventually collapse into starvation, diseases, crime, and misery • Human population only stabilized by positive checks (diseases or famines) • Humans are too lazy and immoral to voluntarily reduce birth rates Limits to Population Growth: Karl Marx View • Population growth is a symptom rather than a root cause of poverty and other social problems • Real causes of social problems are exploitation and oppression • The way to slow population growth and alleviate many social problems (crime, disease, starvation, misery, & environmental degradation) is through social justice Population Growth as Cause Population growth as symptom The Role of Technology in Population Growth • Technological optimists argue that Malthus was wrong in his predictions because he failed to account for scientific progress • Current burst of growth was stimulated by the scientific and industrial revolutions Can More People be Beneficial ? • Advantages of a larger population:  More people mean larger markets, more workers, and increased efficiency due to mass productions of goods  Human ingenuity and intelligence can create new resources  Greater numbers also provide more intelligence and enterprise to overcome problems. E.g.: - Invention of the renewable energy technologies - Increased energy efficiency: better home insulation, increased car performance, efficient lighting… - New environmentally friendly technologies: recycling, bioremediation… - New agricultural technologies that preserve soil and produce more food - Progress in medicine, sanitation, engineering… Human Demography • Demography (Demos: people, graphos: to measure): Encompasses vital statistics about people such as births, deaths, distribution, and population size • October 12, 1999, UN officially declared the human population reached 6 billion (estimation at best) Population Density (persons / square km) Two Demographic Worlds • First is poor, young, and rapidly growing  Less-developed countries (Africa, Asia, Latin America…) - Contain 80% of world population, and will account for 90% of projected growth • Second is wealthy, old, and mostly shrinking  Developed countries (North America, Western Europe, Japan) - Average age is about 40 - Populations expected to decline during the 21st century if current trends continue Estimated Human Population Growth An age structure graph shows the age distribution (%) of a population Changing Age structure of the world Human Population Growth • Human population is growing exponentially (Exponential Growth) • Current world annual growth rate is 1.4% • Doubling time (yrs)= 70/ annual % growth rate • The worldwide human population will double in about 50 years, if the current growth rate persists Future of Human Population • Most demographers believe the world population will stabilize sometime during this century • Projections of maximum population size by 2050: - Low 8 billion - Medium 9.3 billion (most probable) - High 13 billion