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Chapter 7: Human Populations. 7.1 Population Growth. Human populations grew slowly until relatively recently. Population Growth. Until the Middle Ages, human populations were held in check by diseases, famines and wars, and thus grew very slowly.
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7.1 Population Growth • Human populations grew slowly until relatively recently
Population Growth • 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 until 1800 to reach 1 billion. • 150 years to reach 3 billion • 12 years to go from 5 to 6 billion • Human population tripled during the twentieth century. • “Natural Population Control” = Disease, Famine, War
Population Growth • 1 billion: 1810 • 2 billion: 1925 Doubling Time 115 years • 3 billion: 1959 • 4 billion: 1974 Doubling Time 52 years • 5 billion: 1987 • 6 billion: 1999 Doubling Time 40 years • 7 billion: 2012
Population Growth • World War II (1939-45) killed about 60 million people in 6 years (27,000/day) • Global population 2.3 billion 1940 • Global population 2.5 billion 1950 • Population growth 20,000,000 per year • Population growth 55,000 per day • 2x War Death Rate • At no time did the war offset population growth for more than a few days
7.2 Perspectives On Population Growth • Does environment or culture control human populations? • Technology can increase carrying capacity for humans • Population growth could bring benefits
7.3 Many Factors Determine Population Growth • How many of us are there? • Even today we only have estimates • Past population figures are crude • Fertility measures the number of children born to each woman • Replacement = 2.1 • Not all women have children and not all survive • Mortality is the other half of the population equation • Much of our population growth is reduced mortality • Simple sanitation goes a long way
7.3 Many Factors Determine Population Growth • Life span and life expectancy describe our potential longevity • Much of the change is reduced infant mortality • Living longer has demographic implications • More elderly need care • Working longer reduces upward mobility • Emigration and immigration are important demographic factors • Latino influx into the U.S. • The “Eurabia” panic
Limits To Growth • Thomas Malthus (1798) argued human populations tend to increase exponentially while food production is plentiful. • Humans multiply to use available food supply and are vulnerable to collapse. • Human population only stabilized by “positive checks” • “Positive” = “Actively Opposing,” not Necessarily “Desirable” • Humans unlikely to voluntarily reduce birth rates.
Karl Marx • Population growth is a symptom rather than a root cause of poverty and other social problems. • Real causes of these problems are exploitation and oppression. • The way to slow population growth and alleviate many social problems is through social change.
Malthus and Marx Today • Neo-Malthusians - Believe we are approaching, or have already surpassed, the earth’s carrying capacity. • We should make over-population issues our first priority. • Neo-Marxists - Believe eliminating oppression and poverty through social change is the only solution to the population problem. • Wealth and resource distribution must be addressed.
7.4 Ideal Family Size Is Culturally And Economically Dependent • Many factors increase our desire for children • Labor • Old Age Support • Status • Love • Other factors discourage reproduction • Cost (Monetary, Lifestyle) • Negative Status • Could we have a birth shortage?
7.5 A Demographic Transition Can Lead To Stable Population Size • Economic and social development influence birth and death rates • There are reasons to be optimistic about population • Many people remain pessimistic about population growth • Social justice is an important consideration • Women’s rights affect fertility
7.6 Family Planning Gives Us Choices • Fertility control has existed throughout history • Infanticide was the leading method (exposing or abandoning infants) • Oedipus and Romulus and Remus were two Famous Examples in Mythology • Infanticide Condemned by Judaism and Christianity • the exposure of infants is forbidden, which has become a very ordinary piece of wickedness among other nations by reason of their natural inhumanity (Philo Judaeus of Alexandria, Special Laws III c. 30 AD) • Thou shalt not murder a child by abortion, nor again shalt thou kill it when it is born. (Epistle of Barnabas c. 120 AD)
7.7 What Kind Of Future Are We Creating? • Religion and politics complicate family planning • Religious Opposition • Fear of Being “Out-Bred” by Rivals • Suspicion of Motives • Concerns About Intrusion • Rising cost of Labor and Services • Decreasing Tax Base
The Role of Technology • 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. • Malthus never denied these could be factors • He particularly stressed the role of education
The Meaning of Finite You cannot put an infinite amount of anything into a finite space • Therefore we will eventually run out of room You cannot get an infinite amount of anything out of a finite space • Therefore we will eventually run out of new resources
At 2% Per Year • In 573 years there will be one person per square meter over the whole earth • In 1546 years the mass of humanity will equal the mass of the earth • No exponential growth can continue indefinitely
What About Interest? • At 2% per year, a penny invested in 1 AD would be worth $1.6 x 1015 in 2000 AD • Total GNP of World = $60 x 1012 • At 4%, couldn’t be paid in gold because it would outweigh the earth • Works if interest paces growth of economy • Offsets: Inflation, Default, Collapse
In the Long Run, All Growth is Limited • Environmental Resistance • Malthusian: Overshoot plus crash • Logistic: Steady Limit • Human Population Will Stop Growing • When? • How? • Overshoot plus Dieback = Dead Babies, Starvation, War, Genocide, Epidemics
Feedback • Positive: Change More Change • More people more babies more people… • Negative: Change Opposing Force • More babies more expense Reduced Birth Rate • Logistic growth • Early positive feedback phase • Final negative feedback phase
Carrying Capacity of Earth • Solar Energy about 10,000 times global energy use • Global energy use = sunlight on 20,000 square miles (West Virginia) • Globally about 1/3 of arable land is used for crops • If U.S. (5% of population) uses 25% of resources, will take 5 times earth’s resource output to raise everyone to our level
Why Many Oppose Population Control Suspicion of Government • Abuse of Police Powers • Undermine Family Authority • Racial Issues
Why Many Oppose Population Control Economic • Declining markets • Diminished labor pool • Reduced Military Manpower • Reduced Tax Base • Increased Wages and Costs
Why Many Oppose Population Control Religious • Pressure for Abortion • Birth Control • Effects on Sexual Conduct
What Drives Population Growth? • Despite Vatican stance on birth control, most Catholic countries growing slowly • Fastest growth in Africa and South Asia • Many of the fastest growing countries are Moslem • Economic value of large families (farm labor, elder care and support) • Status attached to high fertility
Human Demography Demography - 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. • 7 billion: October 2011 (UN), March 2012 (Census Bureau)
“Third World” • Originally a Cold War Term • First World: U.S. and Allies • Second World: USSR and Allies • Third World: Non-Aligned
“Third World” • First World: Developed • Second World: Semi-Developed • Third World: Non-Developed • Close similarity to Cold War meaning of Third World
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. • North America, Western Europe, Japan. • Average age is about 40. • Populations expected to decline.
Fertility and Birth Rates • Crude Birth Rate - Number of births in a year per thousand. (Not adjusted for population characteristics) • Total Fertility Rate - Number of children born to an average woman in a population during her life. • Zero Population Growth - Occurs when births plus immigration in a population just equal deaths plus emigration.
Mortality and Death Rates Crude Death Rate - Number of deaths per thousand persons in a given year. • Poor countries average about 20 while wealthier countries average about 10. • Some rapidly growing countries have very low crude death rates compared to slower growing countries, due to a higher proportion of young people in the population.
Population Growth Rates • Natural Increase • (Crude Birth Rate - Crude Death Rate) • Total Growth Rate • Includes immigration and emigration
Life Span and Life Expectancy Life Expectancy - Average age a newborn can expect to attain in any given society. • Declining mortality is the primary cause of most population growth in last 300 years. • Worldwide, average has risen from 40 to 65.5 over the past century. • Greatest progress has been in developing countries. • Largely due to curbing infant mortality
