Human population

Chapter 7                    HUMAN POPULATIONS

HUMAN POPULATION HISTORY

Human population was a few million people before the invention of agriculture and domestication of animals about 10,000 years ago.

• 50 million by 5,000 B. C.
• 300 million at the time of Christ.
• I.6 billion in 1900.
• 6 billion in 2000.
• About 6.3 billion in 2003
• In October 10th, 2006, the world population was 6.65 billion.

 

The number of humans tripled during the 20th century.

It took 12 years to go from 5 to 6 billion people.

Check: http://www.ibiblio.org/lunarbin/worldpop
http://www.census.gov/ipc/www/world.html
http://www.census.gov/main/www/popclock.html

LIMITS TO GROWTH: SOME OPPOSING VIEWS

THOMAS MALTHUS

English clergyman and sociologist.

Wrote “An Essay on the Principle of Population as it Affects the Future Improvement of Society…" in 1798.

• Human population increases at an exponential rate

 

• Resources increase arithmetically or not at all.

• Excess population will exhaust its food supply and collapse into crime, starvation and eventually war. Excess population growth is the cause of many social problems.

 

• Human population can become stabilized through positive check (famine, disease) and preventive checks (anything that prevents human births).

• He believed that people were too lazy and immoral to prevent births; he opposed helping the poor.

 

Karl Marx disagreed with Malthus.

• Population growth is a symptom rather than the root of poverty, resource depletion, pollution, etc.

 

• The real causes of poverty are exploitation and oppression.

• Workers will always provide if they have access to means of production and a fair share of the fruits of their work.

 

• Social justice will slow down population growth, and will alleviate crime, disease starvation, and environmental degradation.

Neo-Malthusians believe that we are approaching the carrying capacity of the earth and that we should address the issue of surplus population directly by making birth control the highest priority.

Neo-Marxians believe that the elimination of oppression and poverty through social justice and technology will solve population problems.

1. Today... Can technology make the world more habitable?

 

Food supplies have increased faster than population growth since Malthus time.

Politics rather than lack or resources have caused most of the terrible famines in the last two centuries.

Technological advances have increased the carrying capacity of the earth.

The increase in population we have seen was caused by the industrial and technological revolutions, improvement in agriculture, sanitation and medicine.

Whether progress will continue remains to be seen.

 

2. More people could be beneficial because...

More people means larger markets, more workers, mass production, etc.

It provides more intelligence and enterprise.

New resources can be created through substitution.

• Is the problem excessive population growth or the inordinate consumption of the world's resources by people in rich countries?

 

Some developing-country leaders insist that instead of being obsessed with population growth, we should focus on the inordinate consumption of resources by people in richer countries.

 

HUMAN DEMOGRAPHY

The word demography is derived from the Greek demos, people, and graphos, to write or to measure.

Two demographic worlds:

1. Poor, young, growing rapidly; developing countries in Asia, Africa and Latin America.
2. Rich, slow growth or no growth at all; North America, Europe, Japan, Australia and New Zealand.

 

Many European countries and Japan have negative growth; their populations are decreasing.

AIDS is killing many people especially in Africa.

Africa is still expected to reach one billion people by the end of the XXI century.

Population growth rates:
http://www.photius.com/wfb1999/rankings/population_growth_0.html
http://education.yahoo.com/reference/factbook/countrycompare/pg/1a.html
http://www.lexas.us/worldfactbook/data/people/population_growth_rate.asp

 

Fertility and Birth Rates:

The statistical studies of human populations relating to growth rate, age structure, geographic distribution, etc., and their effects on society and the environment

Crude birthrate: number of births in a year per thousand persons.

Total fertility rate: number of children born to an average woman in a population during her entire reproductive life.

• Paternity in many cases is difficult to establish.
• Some demographers ague that more attention should be given to paternity because in some cultures men have more children than women: multiple wives, female mortality and extramarital affairs.

 

Zero population growth (ZPG): the number of births plus immigration equals deaths plus emigration.

• Adverse results of zero population growth are the lack of manpower to sustain the economy, army and to support those retiring.

 

Crude death rate (crude mortality rate): number of deaths per thousand persons in a year.

• Wealthier countries generally have mortality rates around 10/1000.
• E.g. Costa Rica 4/1000: many young people in fast growing countries.
• E.g. Denmark 12/1000: more older people in slow growing countries.
• There are proportionately more younger than elderly people in rapidly growing countries.

 

Check: http://en.wikipedia.org/wiki/List_of_countries_by_death_rate

 

Natural increase % = crude death rate - crude birth rate.

Total growth rate (%) includes natural increase, immigration and emigration.

Doubling time: divide 70 by the annual or total growth rate.

The world growth rate is 1.2% per year.

• What is the doubling time for the entire world?

 

Potential for longevity

Life span and life expectancy describe the potential for longevity.

Life span is the longest period of life a particular species is known to have survived.

Life expectancy is the average age a newborn can expect to attain in a given society.

• It has risen steadily in most countries over the past 25 years. In the US, life expectancy for men is 75 and for women 80 years.

 

• Declining mortality rather than rising fertility is the primary cause of most population growth.

• Social and environmental factors are responsible for the decline in mortality.

 

Is life expectancy reaching a plateau or advances in science and medicine will extend longevity?

 

Demographic implications of living longer

Dependency ratio: number of non-working compared to the number of working individuals in a population.

There is considerable worry that not enough workers will be available to support retirement systems.

Countries with a large number of pre-reproductive age people will continue to grow for several years even if the fertility rate decreases. This is called the population momentum or echo boom.

 

Immigration and emigration

The UN High Commission on Refugees reported in 2002 there were 19.8 million refugees who had left their country because of political or economic reasons; there were also, 20 million of displaced people in their own countries.

Without immigration, the population of the wealthier nations would be declining.

POPULATION GROWTH: OPPOSING FACTORS

Pronatalist pressures.

These are factors that increase people's desire to have children. Children could be…

• Sources of enjoyment, pleasure and pride.
• A help with household chores.
• A source of current income.
• A source of support for elderly parents.
• A status symbol in society.

 

Society needs to replace members who die or become incapacitated.

This need is often codified in cultural and religious values that encourage having children.

Birth reduction pressures.

Factors that tend to reduce fertility.

• Higher education and personal freedom for women often results in decisions to limit childbearing.
• Desire for activities that interfere with childbearing.
• Cost of raising a child.

 

Education and socioeconomic status are usually inversely proportional to fertility in developed countries.

Birth dearth.

Birth dearth occurs when the birth rate falls below  the replacement level.

Italy, Russia, Austria, Germany, Hungary, Denmark, Greece, Spain, Japan, Singapore, and Taiwan have negative growth.

There is a concern about falling military strength, economic strength and declining social systems due to lack of soldiers, workers and taxpayers.

Europe and North America populations have fallen from 22% of the world’s population in the 1950's to 15% in the 1980's.

It is estimated that by the year 2030, Europe and North America will probably make up around 9% of the world population.

This might erode the powers of western democracies.

Toxins and endocrine hormone disrupters in our environment interfere with sperm production.

Lower sperm production may be the reason for fewer pregnancies in industrialized countries.

DEMOGRAPHIC TRANSITION…

Is the pattern of falling birth rates and death rates as living conditions improve due to economic development.

• This was first noted by the demographer Frank Notestein in 1945.

 

Birth rate increases at first but then fall as societal improvements become permanent.

Populations grow rapidly during the time that death rates have already fallen but birth rates remain high.

It takes some years to change attitudes and values.

Stability is restored at a higher population level.

Most countries in northern and Western Europe went through demographic transition in the 19th or early 20th century.

There are signs that demographic transition is already in progress in many developing countries, e. g. Morocco, Colombia, Mexico, Jamaica, Thailand, Indonesia, etc.

 

VIEWS OF THE FUTURE

1. Optimistic view: birthrate is going down according to some demographers.

• Many developing countries have entered demographic transition.
• Fertility rates have fallen dramatically nearly everywhere in the world.

 

Factors that affect fertility rates are:

• Growing prosperity and social reform that reduce the need for large families.
• Communication has caused a rise in expectations that spur change.
• Less developed countries can learn from mistakes of the past.

 

2. Pessimistic view: developing countries are caught in a demographic trap that prevents them from escaping from the middle phase of demographic transition.

• Birth rate will continue to rise, people will live longer and a catastrophe will occur in the future.
• Environmental deterioration due to human demands, political instability and economic decline prevent these countries from completing modernization.

 

3. Social Justice View: a fair share of the world resources is the key to demographic transition;

• The world has enough resources but inequitable social and economic systems cause maldistribution of those resources.
• Focus on population growth alone will encourage racism and hatred of the poor;
• Poverty, environmental degradation, hunger, etc. are symptom of injustice rather than lack of resources.
• Establish fair system and do not blame the victims.
• Many developed countries were colonial powers and extracted the wealth to pay for their progress from the colonies.

 

4. Ecojustice view: considers the rights of humans and also other species

• Ecojustice seeks an optimum number of humans at which we can provide a decent life while causing a minimum impact on other species.
• Converting landscape into urban and industrial parks crowds out species that have the right to exist.

 

When infant mortality is high, families tend to have many children to ensure that some will survive to adulthood.

Reduction in infant mortality has often accompanied a drop in birth rate.

5. Women’s rights affect fertility

Child survival usually results in fewer births.

When infant mortality is high, parents tend to have many children to insure that some will survive to adulthood.

Land reform, political rights opportunities to earn an independent income, and improved health status of women often are better indicators of total fertility and family welfare than rising GNP>

Check: http://www.fao.org/sd/wpdirect/wpan0001.htm

 

FAMILY PLANNING AND BIRTH CONTROL

Family planning allows couples to determine the number and spacing of their children.

• Barrier methods: condoms, diaphragm, IUD (intrauterine devices), spermicides, vaginal sponge.
• Chemical methods: pills, implantable or injectable progesterone analogs.
• Surgical methods: vasectomy, tubal ligation, Filshie clip.
• Mechanical methods: IUD (intrauterine devices).
• Rhythm method: abstinence from sexual contact during the fertile period of the woman.
• Abstinence.
• Abortion.

 

THE FUTURE OF HUMAN POPULATIONS

Many demographers believe that the world population will become stabilized in the XXI century.

The total number of humans will be between 8 and 10 billion.

Birth rates have begun to fall in East Asia and Latin America. South Asia is expected to start showing a decline in birth rate soon.

Africa will probably continue to increase in population in the 21st. century.

Cultural changes needed to make family planning successful.

• Improve the status of women and children.
• Acceptance of responsibility for our own lives.
• Social security and political stability.
• Knowledge and availability of birth control.