Chapter 7 human population outline population Growth



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OUTLINE

  • Population Growth
  • Perspectives on Growth
  • Factors Determining Growth
    • Fertility and Mortality
    • Life Span and Life Expectancy
  • Factors Influencing Ideal Family Size
  • Demographic Transition
  • Family Planning
  • Future

POPULATION GROWTH

  • Every second 4 or 5 children are born while only 2 people die. There is a net gain of 2.25 people per second.
  • Oct. 31, 2011 world population passed 7 billion and was growing at 1.13% per year.
  • We are adding ~80 million people per year!
  • Global population will double in 62 years if conditions remain unchanged.
  • Jan 1, 2017 population was ~7.4 billion
  • (In 2006 growth rate was 1.2% with a doubling in 58 years – so there is some improvement!)

POPULATION GROWTH IS A RECENT EVENT

  • Until the invention of agriculture 10,000 years ago, the human population was a few million people.
  • Populations were held in check by diseases, famine and war.
  • Early societies regulated their population through cultural taboos, abstinence and infanticide.
  • Human population began to increase rapidly after 1600 due to agricultural developments, better sources of power and better hygiene.
  • 1 billion – 1804 5 billion – 1987
  • 2 billion – 1927 6 billion – 1999
  • 3 billion – 1960 7 billion – 2011
  • 4 billion – 1974 8 billion – 2024??
  • Will we overshoot the carrying capacity?

VIEWS ON POPULATION GROWTH

  • Ecologists are concerned that overpopulation will cause environmental degradation that will threaten the ecological life-support systems on which we depend.
  • Economists often disagree with ecologists, arguing that economic and technological growth will enable us to solve these problems.
  • Social Justice Advocates argue that the root cause of many problems is inequitable distribution of the Earth’s plentiful resources.

PERSPECTIVES ON GROWTH

  • Thomas Malthus (1766-1834) wrote An Essay on the Principle of Population in which he showed that human populations increase exponentially.
  • Population growth is checked by famine, disease, and cultural factors (e.g. late marriage).
  • Malthus believed human population growth causes environmental degradation
  • Karl Marx (1818-1883) believed human population growth results from poverty and resource depletion
  • These two viewpoints are still debated today.

MALTHUS vs MARX

PERSPECTIVES ON GROWTH

  • Joel Cohen – mathematical biologist estimates our carrying capacity at 10-12 billion.
  • David Pimental a entomologist believes we will hit 12 billion in 2100 & birth control should be our #1 priority
  • Mohandas Gandhi stated “There is enough for everyone’s need, but not enough for anyone’s greed.”

TECHNOLOGY CAN INCREASE CARRYING CAPACITY

  • Technology can boost carrying capacity as we make progress in agriculture, engineering, commerce and medicine. These achievements make it possible to support many more people per unit area.
  • However, much of our growth has been based upon cheap, abundant fossil fuels. Will rising fuel prices constrain food production and distribution or some other critical factor?

ENVIRONMENTAL EFFECTS OF POPULATION

  • Effects of population on the environment are not due to numbers alone.
  • I = PAT
  • I = environmental Impact
  • P = Population size
  • A = Affluence
  • T = Technology
  • ie: A single American living an affluent lifestyle produces more pollution than an entire village of farmers in the third world.

CAN MORE PEOPLE BE BENEFICIAL?

  • More people mean larger markets, more workers, and increased efficiency due to mass production.
  • Economist Julian Simon believes that human intelligence and ingenuity will be able to solve the problems associated with population growth. “Humans are the ultimate resource”
  • Many leaders in developing countries believe the inequality of resource use and consumption is the biggest issue to be dealt with.

FACTORS THAT DETERMINE GROWTH

  • DEMOGRAPHY – the study of statistics about people such as births, deaths, distribution, and population size, income, disease, etc.
    • The current estimate for world population is of 7 billion in 2011 is an estimation at best.
      • Many people remain uncounted.
      • Some nations over or understate their numbers for political reasons.
  • 2 DEMOGRAPHIC WORLDS
    • 1 – very poor, young, developing, growing
    • 2 – very old, rich, developed, stable

TWO DEMOGRAPHIC WORLDS

  • DEVELOPING - poor, young, rapidly growing.
    • Less-developed countries in
      • Africa, Middle East, Asia, Latin America
      • Contain 80% of world population, and will account for 90% of projected growth
    • ie: Niger, Yemen – pop growth is 3.2%
        • <10% use of birth control
        • 7 children per woman
        • 50% population < 15 years old

TWO DEMOGRAPHIC WORLDS

  • DEVELOPED - old, wealthy, mostly shrinking.
    • North America, Western Europe, Japan
      • Average age is about 40
      • Populations expected to stabilize or decline (Japan, Italy, Germany)
      • Most couples have 1-0 children
      • Will experience societal issues as the population of young decline and the population of old rise

POPULATIONS OF WORLD’S LARGEST COUNTRIES

DECLINING POPULATIONS

  • RUSSIA – since collapse of Soviet Union is seeing pop. decline due to social issues: poor economy, crime, pollution. Abortions 2x live births. Male life expectancy has gone down
  • AFRICA - the AIDS epidemic has hit Africa the hardest. In Zimbabwe, Botswana, Zambia and Namibia, up to 39% of the population is HIV positive. In Botswana more than 2/3 of the 15 yr. olds now living will die of AIDS. Life expectancy has dropped to 31.6 years. (Should be 69.7 years)

WORLD POPULATION DENSITY

  • POPULATION IS NOT DISTRIBUTED EQUALLY
  • most people live near rivers or coastal plains
  • WORLD POPULATION DENSITY

FERTILITY AND BIRTH RATES

  • CRUDE BIRTH RATE (CBR)- Number of births in a year per thousand. (Not adjusted for population characteristics such as number of women of childbearing age.)
  • TOTAL FERTILITY RATE - number of children born to an average woman in a population during her life (1.9 TFR in the USA)
  • ZERO POPULATION GROWTH – (ZPG) Occurs when births plus immigration in a population equal deaths plus emigration.
    • Generally, this is a rate of 2.1 children per couple, because some people do not have children and some children do not survive.

DECLINE IN FERTILITY RATES WORLDWIDE

  • Fertility rates have declined everywhere except Africa. 100 out of 220 countries are at or near 2.1 replacement rate.
  • Greatest fertility reduction has been in Southeast Asia.
  • CHINA’S one child policy has decreased the fertility rate from 6 in 1970 to 1.5 in 2010.
  • THAILAND decrease fertility from 7.0 in 1979 to 1.64 in 2009 by distributing condoms

MORTALITY AND DEATH RATES

  • CRUDE DEATH RATE (CDR) - 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 due to a high proportion of young people.
  • NATURAL INCREASE - crude birth rate minus crude death rate. Expressed as % (per hundred)
  • TOTAL GROWTH RATE includes immigration and emigration, as well as births and deaths. Expressed as % (per hundred)

INFANT MORTALITY MAP

  • Infant Mortality - # of deaths <1 year old / 1000
  • Child Mortality - # of deaths <5 year old / 1000

Calculating World Population Growth Rate

  • Global Population Growth Rate = (CBR – CDR) 10
  • (Divide by 10 to arrive at a % because the birth and death rates are expressed per 1000 people)
  • Calculate: WPGR....
  • In 2014 there were 20 births & 8 deaths per 1000
  • Now calculate the Doubling Time!

Calculating National Growth Rate: 1 Country

  • National PGR =
  • (CBR + immigration) – (CDR + emigration) 10
  • (Divide by 10 to arrive at a % because the birth and death rates are expressed per 1000 people)
  • Calculate: NPGR....
  • 2014 CBR = 13, immigration = 3.2, CDR = 7, emigration = 0.1
  • Now calculate the Doubling Time!

LIFE SPAN and LIFE EXPECTANCY

  • LIFE SPAN – is the oldest age to which a species is known to survive
  • 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, the average has risen from 30 to 70 over the past century.
    • Longer life expectancy is not due to medicine, but rather improved nutrition, sanitation, and education.
    • Generally, women live longer than men

WORLD LIFE EXPECTANCY

LIFE EXPECTANCY AT BIRTH

LIFE EXPECTANCY AND GNP

POPULATION MOMENTUM

  • A population growing rapidly due to natural increase has more young people than does a stationary population.
    • Even if total fertility rates were to fall, the population would continue growing as young people enter reproductive age (POPULATION MOMENTUM).
  • Some countries now have a stable population with the same number of people in each age group.

AGE STRUCTURE

AGE STRUCTURE

LIVING LONGER HAS IMPLICATIONS

    • Declining populations have more old people than young people.
    • Both rapidly and slowly growing countries can have a problem with dependency ratio.
  • DEPENDENCY RATIO - The number of non-working compared to working individuals in a population.
      • ie: In the U.S., fewer working age people will support many more retired people, and this is a problem for the Social Security & retirement systems.
      • ie: In Mexico, fewer working age people support many children – can lead to conditions of poverty

EMIGRATION (out) and IMMIGRATION (in)

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

IDEAL FAMILY SIZE

  • SOCIAL, CULTURAL, RELIGIOUS AND ECONOMIC FACTORS AFFECT FAMILY SIZE.
  • 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 and labor
      • Social status
      • Replace members in society as they die

PRONATALIST PRESSURE cont.

  • Society’s need to replace its members may be codified into cultural or religious values.
    • Families with few children are pitied.
    • Controlling fertility may be taboo.
    • Boys are valued more than girls because they carry on the family name and often are expected to financially support parents in old age.
    • Couples may have more children than they really want in order to have a boy.
    • Having a large family in some cultures is a source of male pride.

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 many 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, rather than decreasing as it does in developed countries.
  • In less-developed countries, adding another child to a family usually does not cost much
  • In DEVELOPED COUNTRIES, raising an additional child can carry significant costs.

BIRTH RATES IN THE UNITED STATES

  • Falling rate 1910-1929 due to transition from agricultural to industrial society
  • Baby boom after WWII – 1945-1965
  • Echo Boom as Baby-Boomers had children – smaller increase due to economics
  • FERTILITY OFTEN FOLLOWS ECONOMICS

COULD WE HAVE A BIRTH DEARTH?

  • Most European countries, as well as Russia, Asia, Japan, Singapore and Taiwan, are experiencing negative growth rates.
    • There are concerns in all these countries about a lack of young people to be soldiers, workers, and taxpayers.
  • One reason that birth rates may have dropped in developed countries is that toxins and endocrine disrupters that are pollutants interfere with sperm production. Sperm numbers and quality have fallen by half in the last 50 years.

DEMOGRAPHIC TRANSITION MODEL

DEMOGRAPHIC TRANSITION

  • Pattern of falling death rates and birth rates due to improved living conditions accompanying economic development.
    • PRE-MODERN SOCIETY - Poor conditions keep death rates high; birth rates are correspondingly high. (Stage I)
    • ECONOMIC DEVELOPMENT - brings better standard of living thus death rates fall. Birth rates stay constant or even rise. (Stage II)

DEMOGRAPHIC TRANSITION CONTINUED

  • In a MATURE INDUSTRIAL ECONOMY - birth rates begin to fall as people see that most of their children survive. (Stage III)
    • Populations continue to grow due to population momentum.
  • DEVELOPED COUNTRIES - Transition is complete and both death and birth rates are low and population is in equilibrium. (Stage IV)

IS DEMOGRAPHIC TRANSITION HAPPENING NOW?

  • Four conditions necessary for demographic transition:
    • improved standard of living
    • confidence that children will survive
    • improved status of women
    • birth control
      • Thailand, Indonesia, Colombia, Iran reduced fertility by 50+% in 20 years
      • Morocco, Peru, Jamaica, Mexico reduced fertility by 30-40% in 20 years

CAN DEMOGRAPHIC TRANSITION HAPPEN NOW?

  • Some demographers think that a demographic transition is taking place now in developing nations.
    • Growing prosperity and social reforms
    • More readily available technology
    • Developing countries can learn from past mistakes or developed countries
    • Modern communication increases expectations for change & development

DEMOGRAPHIC TRANSITION NOW?

  • Others take a more pessimistic view. Economist, Lester Brown warns that poorer countries may be caught in a demographic trap.
  • The population is growing so rapidly that there are not enough resources to complete modernization and enter stage IV.
  • Political instability & economic decline may be to blame
  • People who take this view urge birth control, education, and national policies that limit population growth.

SOCIAL JUSTICE

  • Still other demographers believe that in order for the demographic transition model to work, resources must be distributed more equitably.
    • They believe that the world has enough natural resources, but inequitable social and economic systems cause mal-distribution.
    • Many rich countries, when they were colonial powers, extracted the wealth from countries that were their colonies. Some of the world’s poorest countries had rich resources and adequate food supplies before they were impoverished by colonialism.

OTHER RIGHTS

  • Should consider the rights of other species?
    • Perhaps, rather than asking what is the maximum number of people that Earth can hold, we should instead ask what is the optimum number of people at which we can provide a fair and decent life for all humans while causing the minimum impact on other species and the biosphere.

WOMEN’S RIGHTS AND FERTILITY

  • Education and job opportunities for women reduce fertility rates.
  • When child mortality is high, parents tend to have high numbers of children to ensure that at least some survive. Improving child survival would reduce the number of births.
  • Land reform, political rights, job opportunities for women, and improved health for women translate into better survival for children and therefore lower fertility.

FERTILITY vs EDUCATION

FAMILY PLANNING and BIRTH CONTROL

  • FAMILY PLANNING - allows couples to determine the number and spacing of their children
  • - not necessarily fewer children, just decisions to have/not have more/less children
  • BIRTH CONTROL - methods used to reduce births
  • 1. Avoidance - abstinence, delayed marriage
  • 2. Mechanical barriers – condoms, diaphragm
  • 3. Surgical Methods - vasectomy, tubal ligation
  • 4. Hormones – progesterone (f), gossypol (m)
  • 5. Barriers to implantation – IUD
  • 6. Abortion

BIRTH CONTROL METHODS

Percentage of married women with two children who do NOT want another child.

Garret Hardin’s Life Boat Ethic

  • “Each rich nation amounts to a lifeboat full of comparatively rich people. The poor of the world are in other much more crowded lifeboats. Continuously, the poor fall out of their lifeboats and swim for awhile, hoping to be admitted to a rich lifeboat, or in some other way to benefit from the goodies on board.... We cannot risk the safety of all the passengers by helping others in need. What happens if you share space in a lifeboat? The boat is swamped and everyone drowns. Complete justice, complete catastrophe.”

FUTURE OF HUMAN POPULATIONS

  • Most demographers believe the world population will stabilize sometime during the next century.
  • Projections of maximum population size
    • Low - 7 billion by 2050, then fall to 6 billion by 2150
    • Medium - 8.9 billion by 2050 then stabilize
    • High - continue to grow to 25 billion by 2150
  • High unmet need for family planning. Women in poorer nations often desire family planning but do not have access to it.

FACTORS THAT COMPLICATE FAMILY PLANNING

  • Religion and politics
    • U.S. was a leader in the International Conference on Population and Development in which 179 countries endorsed universally available family planning. Stipulation that abortion should never be promoted as family planning.
    • U.S. withdrew its financial support in 2000 as the political climate changed. (Bush) Claimed that ICPD could be interpreted as pro-abortion.

FACTORS THAT COMPLICATE FAMILY PLANNING

  • Some religions forbid birth control & encourage couples to have as many children as possible.
  • Societal changes are often needed to make family planning programs successful.
    • Improved education & status for women
    • Improved status for children
    • Idea that we should have control of our lives
    • Social security and political stability
    • Effective & acceptable birth control methods


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