BIOLOGY 1105

LECTURE OUTLINE

CHAPTER 8 - Human Population

I. Central Case: One-Child Policy

A. The People= s Republic of China is the world= s most populous nation, home to one-fifth of the 6.5 billion people living on Earth at the start of 2006.

B. Under Mao Zedong= s leadership, improved food production and distribution and better medical care allowed China= s population to swell, causing environmental problems.

C. The government instituted a population-control program in the 1970s.

1. The program started with education and outreach efforts encouraging people to marry later and have fewer children, and increasing the accessibility of contraceptives and abortion.

2. In 1979 the government decided to institute a system of rewards and punishments, enforcing a one-child limit per family.

D. China= s growth rate is down to 0.6%; however, there have been unintended consequences of the program, such as widespread killing of female infants and an unbalanced sex ratio.

II. Human Population Growth: Baby 6 Billion and Beyond

A. The human population is growing nearly as fast as ever.

1. The human population has doubled since 1964.

2. Since 1975 the world= s population has added one billion humans every 12 years.

B. Is population growth really a A problem@ ?

1. Our ongoing burst of population growth has resulted from technological innovations, improved sanitation, better medical care, increased agricultural output, and other factors that have led to a decline in death rates, particularly a drop in infant mortality.

2. There are many people today who deny that population growth is a problem.

3. Under the Cornucopian view, resource depletion as a consequence of greater numbers of people is not a problem if new resources can be found to replace the depleted resources.

4. Environmental scientists argue that not all resources are replaceable by others once they are depleted, and that few resources are actually created by humans.

5. Even if resource substitution could enable indefinite population growth, could we maintain the quality of life that we would desire, or would our descendants have less space, less food, and less material wealth than the average person does today?

 

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6. Many governments have found it difficult to let go of the notion that population growth increases a nation= s economic, political, and military strength.

C. Population is one of several factors that affect the environment.

1. The IPAT model represents how human= s total impact (I) results from the interaction among three factors - population (P), affluence (A), and technology (T): I = P x A x T.

2. A sensitivity factor (S) can be added to the equation to denote how sensitive a given environment is to human pressures:

I = P x A x T x S.

3. Impact can generally be boiled down to either pollution or resource consumption.

4. Modern-day China shows how all elements of the IPAT formula can combine to result in tremendous environmental impact in very little time.

III. Demography

A. Demography is the science of human population.

1. The principles of population ecology apply to humans.

2. Like other organisms, humans have a carrying capacity set by environmental limitations on our population growth.

3. Estimates of the human carrying capacity have ranged greatly - from 1-2 billion people living prosperously in a healthy environment to 33 billion living in extreme poverty in a degraded world without natural areas.

B. Demography is the study of human population.

1. The application of population ecology principles to the study of statistical change in human populations is the focus of the social science of demography.

2. Population size is the absolute number of individuals.

3. People are very unevenly distributed over the globe.

a. This uneven distribution means that certain areas bear far more environmental impact than others.

b. At the same time, areas with low population density are often vulnerable to environmental impacts. The reason they have low population may be that they are sensitive and cannot support many people.

4. Age structure diagrams show the relative sizes of each age group in a population and are especially valuable to demographers in predicting future dynamics of a population.

5. The ratio of males to females, the sex ratio, can also affect population dynamics.

a. The naturally occurring sex ration in human populations at birth features a slight preponderance of males.

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b. In China, selective abortion of female fetuses has skewed the natural sex ratio.

C. Population growth depends on the rates of birth, death, immigration, and emigration.

1. In today= s world, immigration and emigration are playing an increasingly large role because of the flow of refugees.

2. Since 1970, growth rates in many countries have been declining and the global growth rate has declined, partially because of a steep drop in birth rates.

D. A population= s total fertility rate influences population growth.

1. The total fertility rate (TFR) is the average number of children born per female member of a population during her lifetime.

2. Replacement fertility is the TFR that keeps the size of a population stable; for humans, it is 2.1.

3. A lower infant mortality rate has reduced people= s tendency to conceive many children in order to ensure that at least some survive.

4. Many other social factors play a role in reducing the emphasis on child rearing.

5. The natural rate of population change is the change due to birth and death rates alone, excluding migration.

E. Some nations have experienced a change called the demographic transition.

1. Life expectancy is the average number of years that an individual in a particular age group is likely to continue to live.

2. Demographic transition is a theoretical model of economic and cultural change that explains the trend of declining death rates and birth rates that occurs when nations become industrialized.

3. The first stage, the pre-industrial stage, is characterized by conditions in which both death rates and birth rates are high.

4. In the next stage, the transitional stage, death rates decline and birth rates remain high.

5. The industrial stage creates employment opportunities, particularly for women, causing the birth rate to fall.

6. In the final stage, the post-industrial stage, both birth rates and death rates remain low and populations stabilize or decline slightly.

F. Is the demographic transition a universal process?

1. This transition has occurred in many European countries, the United States, Canada, Japan, and several other developed nations over the past 200-300 years.

2. It may or may not apply to all of the developing countries depending on their culture, especially if they place greater value on grant women fewer freedoms.

 

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IV. Population and Society

A. Women= s empowerment greatly affects population growth rates.

1. Drops in TFR have been most noticeable in countries where women have gained improved access to contraceptives and education, particularly family-planning education.

2. Unfortunately, many women still lack the information and personal freedom of choice to allow them to make their own decisions about when to have children and how many to have.

3. In societies in which women are freer to make reproductive decisions, fertility rates have fallen, and the children are better cared for, healthier, and better educated.

B. Population policies and family-planning programs are working around the globe.

1. The government of Thailand has relied on an education-based approach to family planning that has reduced birth rates and slowed population growth.

2. India has had long-standing policies, but some think they need to be strengthened.

3. Brazil, Mexico, Iran, Cuba, and many other developing countries have instituted active programs consisting of population reduction targets, incentives, education, contraception, and reproductive health care.

4. In 1994, the United States hosted a conference in Cairo on population and development, at which 179 nations endorsed a platform calling for all governments to offer universal access to reproductive health care within 20 years.

5. Despite the successes of family planning internationally, the United States has often declined to fund family-planning efforts by the United Nations. For example, canceling this funding was one of George W. Bush= s first acts upon becoming U.S. president in 2001.

C. Poverty is strongly correlated with population growth.

D. Consumption from affluence creates environmental impact.

1. Individuals in affluent societies leave a larger A ecological footprint.@

E. The wealth gap and population growth contribute to violent conflict.

1. In 1999, the richest 20% of the world= s people used 86% of the world= s resources, and had over 80 times the income of the poorest 20%.

F. HIV/AIDS is a major influence on populations in parts of the world.

1. Of the 38 million people around the world infected with HIV/AIDS in 2004, 25 million lived in the nations of sub-Saharan Africa.

2. The AIDS epidemic is unleashing a variety of demographic changes.

3. Premature deaths, of both infants and young adults, are reducing the average life expectancy in African nations.

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G. Severe demographic changes have social, political, and economic repercussions.

1. Everywhere in sub-Saharan Africa, AIDS is undermining the ability of developing countries to make the transition to modern technologies because it is removing many of the youngest and most productive members of society.

2. Governments of AIDS-infected countries are experiencing demographic fatigue.

V. Conclusion

A. Although global populations are still growing, the rate of growth has decreased nearly everywhere.

B. There has been progress in expanding rights for women worldwide. In addition to the clear ethical progress of this development, it also helps to slow population growth.

C. True sustainability demands that we stabilize our population size in time to avoid destroying the natural systems that support our economies and societies.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

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