Chapter 7: Human Populations

Population Growth

World population reached 6 billion in July, 1999

There are various views as to the impact of rapid population growth

• Growth beyond carrying capacity may threaten the ecological balance of the world • More people may be beneficial, i.e., more hands and brains to solve problems (supported by economists) • Growth is only a symptom of mis-managed resources that have the potential to support everyone

Human Population History

World population grew slowly until relatively recently

Many factors contributed to a slow, steady population growth

• Cultural practices such as infanticide • Epidemic disease and famine • War

Period of rapid growth that we are experiencing now raises questions

• Can high levels of growth be maintained? • Will a dieback of our population serve to balance the current trend?

Limits to Growth: Some Opposing ViewsMalthusian Checks on Population

Rev. Thomas Malthus, 1798

• Theory predicted collapse of human population due to lack of food supply • He believed population growth supported increases in starvation, poverty, social ills • Supported idea that (1)destructive and (2) preventative checks could slow population growth (1) Disease or famine (2) Moral restraint or celibacy to curb reproduction

Karl Marx - A critic of Malthus • Population growth is a symptom of social injustice rather than a cause • Supported the idea that productive, working citizens could always provide for themselves and society

Malthus and Marx Today

Neo-Malthusians: Name for supporters of Malthus and support predictions of exceeding the world carrying capacity

Neo-Marxians: Name for supporters of Marx and support use of technological improvements to equalize social injustices andsolve population problems

Can Technology Make the World More Habitable?

• Food production is outpacing population growth

• Easy acquisition of resources has supported increased carrying capacity

• Technological advancements: - Medicine - Sanitation - Commerce - Agricultural productivity

Can More People Be Beneficial?

More people may mean more intelligence for problem solving and creating new resources

Julian Simon: A primary supporter of humans existing as the ultimate resource

Human Demography

Demography: to write or measure e.g., birth, death, and growth rates of people

How Many of Us Are There?

Exact numbers are unavailable due to political instabilities and inaccurate record keeping

Most growth is expected in less developed countries

• To check the current and predicted world population size, go look at the World• Population Clock (close the new window to return to these pages). (located at "http://sunsite.unc.edu/lunarbin/worldpop")

Fertility and Birthrates

• Fertility rate describes actual production of offspring • Crude birthrate: unadjusted for number of births per thousand individuals • Total fertility rate: average number of children per life time • Zero population growth (ZPG): number of births needed for a stable population Examples: - Fertility Rate for developed countries = 2.1 - Fertility Rate for the world = 2.8• High fertility usually associated with poverty: e.g., Sub-Saharan Africa • Low fertility associated with low level of modernization, and high death rates: e.g., Eastern Block countries

Fertility and Birthrates

• Fertility rate describes actual production of offspring • Crude birthrate: unadjusted for number of births per thousand individuals • Total fertility rate: average number of children per life time • Zero population growth (ZPG): number of births needed for a stable population Examples: - Fertility Rate for developed countries = 2.1 - Fertility Rate for the world = 2.8• High fertility usually associated with poverty: e.g., Sub-Saharan Africa • Low fertility associated with low level of modernization, and high death rates: e.g., Eastern Block countries

Mortality and Death Rates

High rate: 20/1000 in African countries

Low rate: 5/1000 in young, growing countries: e.g., Belize

Population Growth Rates

• Annual Death rate subtracted from Birthrate = natural increase (%) - Divide percent (# per 100) into 70 = approximation of years to

double population• Total growth rate includes natural increase plus immigration and

emmigration • Examples: - Even though the United States and Canada have the same rate of

natural increase (0.8% per year), the total growth rate, which includes immigration and emmigration, is much faster for the U. S. (high immigration, low emmigration compared to Canada)

- Fast: Afghanistan = 5.3% per year - Slow: Eastern Europe = negative, with declining populations - World growth rate = 1.4% per year, doubles every 50 years

Life Span and Life Expectancy

• Life span is the oldest absolute age of an individual • Life expectancy is the average age at death for a population - Life expectancy has increased due to better food and sanitation

reducing mortality - If life expectancy changes, many facets of society will also

change: expected to be over 60 years of age for U.S. in 2100

Living Longer: Demographic Implications

• As developing countries gain access to education, medicine, and sanitation, life expectancy increases

• Over past 100 years: life expectancy increased from 40 to 65.5 years of age worldwide

• Good correlation between income and life expectancy (up to about $4,000 U.S.)

- levels out at 75 years of age for men, 80 for women

• Age structure has impact on society - A large ratio of young citizens will affect population fertility for

long periods, population momentum, e.g., Mexico - A large ratio of old citizens will affect productivity, dependency

ratio

Emigration and Immigration

• 38 million people left home countries in 1997 • Refugees can affect places they leave and the places they move into e.g., uninhabited rainforest seen as a good place to move from crowded cities • Movement of large numbers of people can create ecological, financial, and social change

Population Growth: Opposing Factors

Pronatalist Pressures

• A strong desire to have children is more important than inadequate contraception

• Number of children often linked to societal status

Birth Reduction Pressures

• Developed countries: education and socioeconomic status are inversely related to fertility. Families tend to commit to a lownumber of highly cared for children

• Undeveloped countries: as education and socioeconomic status rise so does fertility

Birth Dearth?

A lack of replacement births can affect many aspects of a productive country

• Military strength • Work force • Taxpaying workers

Demographic Transition

Transition from high birth and death rates to lower birth and death rates

Development and Population

As death rates fall and birthrates remain high in some developing countries, total population growth transition curves are unexplained by past experience

An Optimistic View

Fertility rates are dropping in developing countries such as Morocco, Peru, Columbia, Thailand, Jamaica, and Mexico

Developing countries are experiencing the technological benefits that move from developed countries which reduce needs for large families

A Pessimistic View

Lester Brown, Garret Hardin

Lifeboat analogy: wealthy countries are in well supplied, uncrowded lifeboats. If these lifeboats admit struggling survivors, soon the boat is overcrowded and no better than the crowded boat left by the survivor. Resources cannot be shared by all.

A Social Justice View

There may be enough resources for everyone if they are distributed in a fair and equal system of social justice

May be important to share resources from wealthy nations with developing nations due to inherent sharing of the environment

An Ecojustice View

Seeking the optimum number of people that provides a fair and decent life for all humans while causing the minimum impact onnonhuman species. Considers the 'right' of all species to exist.

Infant Mortality and Women’s Rights

Reductions in infant mortality always precede reductions in birthrates

Child survival will benefit from and increase in adult female rights and opportunities

Family Planning and Fertility Control

Birth control: any method to control births

Traditional Fertility Control

Ancient societies maintained stable population sizes

Use of social conventions, medicines, abortions, infanticide

Current Birth Control Methods

• Avoidance of fertile periods: rhythm method • Mechanical barriers: Female condom • Surgical methods to prevent release of gametes • Chemicals: Norplant: sub-cutaneous implanted, slow release

progesterone; RU486, the morning after pill • Physical disruption of implantation, IUD • abortion

New Developments in Birth Control

• Vaginal rings loaded with progesterone • Anti-pregnancy vaccines • Anti-sperm vaccines • Sperm and egg suppression chemicals: gonadotropin releasing

hormone agonists

The Future of Human Populations

• An expected equilibrium world population is 8 -10 billion • Change is required for a stable and sustainable world population • Approximately 50% of married couples in the world use family planning - Family planning success needs: - Improved women's rights - Improved status for children - Support for fertility decision making - Social and political stability