Human Populations

Outline: Population Growth Limits to Growth Human Demography Fertility and Mortality Life Span and Expectancy Population Growth - Opposing Factors Demographic Transition Family Planning Future of Human Populations

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 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.

Human Population History

Population Growth World War II (1939-45) killed about 40 million people in 6 years Global population 2 billion + Growth about 2% a year Population growth 40,000,000 per year Population growth 110,000 per day At no time did the war offset population growth

LIMITS TO GROWTH Thomas Malthus (1798) argued human populations tend to increase exponentially while food production is plentiful. Humans inevitably outstrip food supply and eventually collapse. Human population only stabilized by positive checks. Humans are too lazy and immoral 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.

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.

Technological Optimism

Technological Optimism

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 = $3.5 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?

Feedback Positive: Change More Change More peoplemore babiesmore people… Negative: Change Opposing Force More babiesmore expense 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 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

Population Growth Rates

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.

Population Density (persons / square km)

“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

North vs. South?

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.

Corruption Index

Estimated Human Population Growth

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

Life Expectancy-1930

Life Expectancy-1960

Life Expectancy-1990

Demographic Implications of Living Longer A population growing rapidly due to natural increase has more young people than a stationary population. Both rapidly and slowly growing countries can have a problem with dependency ratio. The number of non-working compared to working individuals in a population.

Emigration and Immigration Emigration and Immigration play a large role in human population dynamics. Developed regions expect 2 million immigrants a year for next 50 years. Immigration is a controversial issue. “Guest workers” often perform dangerous or disagreeable work, while being paid low wages with few rights. Locals complain immigrants take away jobs and overload social services.

POPULATION GROWTH, OPPOSING FACTORS Pronatalist Pressures Factors that increase the desire for children. Source of pleasure, pride, comfort. Source of support for elderly parents. Current source of family income. Social Status Replace members in society as they die. Boys frequently valued more than girls.

Birth Reduction Pressures Higher education and personal freedom for women often result in decisions to limit childbearing. When women have more opportunities to earn a salary, they are less likely to have children. Education and socioeconomic status are usually inversely related to fertility in wealthier countries.

Birth Reduction Pressures In developing countries, higher income often means families can afford more children, thus fertility often increases. In less-developed countries, adding another child to a family usually does not cost much, while in developed countries, raising an additional child can carry significant costs.

DEMOGRAPHIC TRANSITION Model of falling death rates and birth rates due to improved living conditions accompanying economic development. Pre-Modern Society - Poor conditions keep death rates high, thus birth rates are correspondingly high. Economic Development brings better conditions and standard of living thus death rates fall. Birth rates stay constant or even rise.

Demographic Transition Eventually, birth rates begin to fall. Populations grow rapidly in time between death rates and birth rates fall. Developed Countries - Transition is complete and both death and birth rates are low and population is in equilibrium

Demographic Transition

United States Birth Rate “Pig in a python”

Optimism or Pessimism Some demographers believe the Demographic Transition is already taking place in developing countries, and world population should stabilize during the next century. Others argue that many poorer countries are trapped in the middle phase of transition, and that their populations are growing so rapidly that human demands exceed sustainable resource yields.

Social Change Still other demographers believe that in order for the Demographic Transition model to work, resources must be distributed more equitably. The world has enough natural resources, but inequitable social and economic systems cause maldistribution.

FAMILY PLANNING Family Planning allows couples to determine the number and spacing of their children. Birth Control - Any method used to reduce births. Traditional Methods Long breast-feeding, taboos against intercourse while breast-feeding, celibacy, folk medicines, abortion, infanticide.

Birth Control Current Methods Avoidance of sex during fertile periods. Mechanical barriers preventing contact between sperm and egg. Surgical prevention of sperm or egg release. Chemical prevention of sperm or egg maturation, release, or implantation. Physical barriers to implantation. Abortion

FUTURE OF HUMAN POPULATIONS Most demographers believe the world population will stabilize sometime during the next century. Projections of maximum population size: Low 8 billion Medium 9.3 billion High 13 billion

One Last Demographic Effect of Population Growth Equals Regulation

Summary: Population Growth Limits to Growth Human Demography Fertility and Mortality Life Span and Expectancy Population Growth - Opposing Factors Demographic Transition Family Planning Future of Human Populations