Human Population

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Human Population

• Growth, Demography and Carrying Capacity

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• Reasons for the patterns of growth
• Reason for slow population growth prior to 1830,
  disease.
• Smallpox
• Black plague
• Diphtheria
• Typhoid fever
• Breakthroughs
• Discovery of cause and prevention of disease
• Better care of drinking water and sewage problems
• Discovery of antibiotics
• Better nutrition.
• This pattern of change has led to epidemiologic
  transition. Change due to decrease in diseases.

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• World population growth rate
• Peaked at 2.1 in 1960s average of 5 children
  per woman
• Declined steadily since then about 2.8 per
  woman
• BUT
• All the babies born in the 1960s became parents
  about 20 years later.
• Result, the number added per year was 87 million
  people in the 1980s.

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FACTORS AFFECTING HUMAN POPULATION SIZE

• Population change is calculated by subtracting
  the number of people leaving a population
  (through death and emigration) from the number
  entering it (through birth and immigration)
  during a specified period of time
• births
  deaths
  
• Population change
  Immigration emigration
• When these factors balance, zero population
  growth occurs (ZPG)

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• Doubling time is calculated by the rule of 70.
• 70/percentage growth rate doubling time in
  years
• This formula can be used to calculate the
  doubling time for anything. (Good formula to
  remember)

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• Demographers use the birth rate (the number of
  live births per 1,000 people)
• Death rate, (the number of deaths per 1,000
  people)
• The rate of population is usually expressed as a
  percentage

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• The problem of exponential population growth has
  not disappeared, its just occurring at a slower
  rate.
• Even a 15 growth per year can lead to enormous
  increases in population size over a 100 year
  period.
• The current world growth is 1.43 per year. That
  is equivalent to adding another Los Angeles to
  the world every 3 weeks. A United States every 3
  years.

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• Two types of fertility rates affect a countrys
  population size and growth rate.
• Replacement level fertility. This is the number
  of children a couple bear to replace themselves.
• It is slightly higher than 2 children per couple.
• Lowering fertility rates to replacement levels
  does not mean an immediate halt in population
  growth.

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• This is because there are already so many future
  parents already alive.
• Even if a country reached replacement level
  population growth. The population would continue
  to grow for 50 years.
• This is because of high growth rates in the past.
  This results in what is known as population
  momentum.

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• Total fertility rate (TFR) is an estimate made of
  the average number of children a woman will have
  during her childbearing years under current
  age-specific birth rates.

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• The total fertility rate in developing countries
  dropped from 6.5 in 1950 to 3.3 in 1998.
• This rate must drop to 2.1 for world population
  to stabilize sometime during the next century.

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• Rich country vs poor country
• Three main economic categories
• High income, highly developed, industrialized
• US, Canada, Australia,
• Gross income above 9,206
• Make up just 1 Of world Population
• Control about 81 of worlds wealth
• Middle income, moderately developed
• Mexico Central America, South Amrerida
• Per capita gross income 745-9,205
• Low income developing
• Eastern, western and central Africa, India, Asian
  countries
• Less than 745 - average 430
• 41of population, 3.4 of worlds wealth

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• Population Growth in Rich and Poor Nations
• Developed world (965 million) is growing at a
  rate of 0.1 per year
• Remaining population (5.35 billion on 2003) is
  growing at a rate of 1.6 per year
• WHY?
• Fertility
• Total fertility rate of 2.0 will give a stable
  population.
• TFR of more than 2.0 give a growing pop.
• TFR of less than 2.0 lead to a declining pop.

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• Because infant and child mortality are not zero,
  the actual replacement level fertility is 2.1 for
  developed countries
• The actual TFR of for developed is not about 1.5
  for developed countries
• The one exception is the US, with a TFR of 2.0 in
  2003
• The TFR of most developing countries is around
  3.1, with some as high as 5 or more.
• This will cause population doubling in 20-40
  years.

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• This will cause the populations of more wealthy
  countries to decline and those of less developed
  countries will continue growing.
• Population projections by 2075
• 90 of world population in developing countries
  currently 84

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• IPAT formula
• I P X A X T
• Environmental impact population x affluence x
  technology
• The average American places at least 20 times the
  demand on Earth resources than the average person
  in Bangladesh.

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• Enter Stewardship
• I P X A X T
• S
• Developed countries have to deal with
• consumption
• Affluence
• Damaging technologies (eg. batteries, computers,
  old cars)
• Wastes
• We need to moderate these and become good
  stewards.

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• Consequences of population growth and affluence.
• The US consumes the largest share of 11 of 20
  major commodities
• Aluminum, coffee, copper, corn lead, oil,
  oilseeds, natural gas, rubber, tin, zinc
• Eat more than three times the global average of
  meat
• Lead the world in paper consumption
• We also can affect the environment positively
• Safe drinking water,
• Sewer systems
• Collection and disposal of refuge
• Not destroying our parks and woodlands

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• Lead the world in pollutants
• Using fossil fuels
• Emissions of CO2.
• Emitting CFCs
• Production of nuclear waste
• Acid rain
• Consuming common resources
• Exploiting world fisheries
• Harvesting old growth forests in S.America to
  make fax paper.
• Harvesting exotic tropical wood for furniture.

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• To generalize the effect of affluence
• enables the wealthy to clean up their immediate
  environment and ship the waste off to more
  distant locations.
• We obtain resources from distant locations
• We isolate ourselves
• We are unaware of the stress we put on the
  environment

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Population Profile

• Often called population pyramids
• Used by demographers
• Used to anticipate needs of a population
• Snapshot of the population at the time
• Projections are not always accurate
  demographers make predictions based on fertility,
  morals, migration
• Looking at the population of a given age group is
  an echo of past events that affected birthrates
• Planning tool
• Realistic planning for future demands for goods
  and services

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How have fertility rates changed in the US?

• The population of the US has grown from 76
  million in 1900 to 270 million in 1998. this is
  a 2.6 fold increase.
• The total fertility rate was 3.7 in the post WWII
  baby boom.
• Since 1972 it has remained at or below
  replacement level.
• However the US has the highest immigration rate
  of any industrialized country.

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• The drop in the total fertility rate has led to a
  decline in the rate of population growth in the
  US, however the country's population is still
  growing faster than that of most developed
  countries.
• Including immigration the US population of 270
  million grew by 1.17 in 1998.
• This is more that double the mean rate of the
  worlds industrialized nations.
• This growth added about 3.1 million people. 1.8
  million, more births than deaths, 935,000 legal
  immigrants and 400,000 illegal immigrants.

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• The pop of the US reversed in late 1980s and
  started back up
• US population projected to be 420 million by
  2050.
• See your book page 142

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• Large number of baby-boom women who are still in
  their childbearing years. An increase in the
  number of unmarried mothers (including
  teenagers).
• A continuation of higher fertility rates for
  women in some racial and ethnic groups than for
  Caucasian women.
• High levels of legal and illegal immigration
  (accounts for 43 of current US population
  growth.
• Inadequate family planning services, especially
  for the poor.

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Increasing Fertility Rates And Environmental
Problems For California

• California is the most populous US state. 33
  million people in 1998.
• States pop tripled between 1950 and 1998.
• CAs TFR rate rose from 1.9 to 2.5 between 1985
  and 1998.
• Much of the increase is due to the high fertility
  of the immigrants.
• CA takes in more legal and illegal immigrants
  than any other state.

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• The environmental impact has been that
• Most of the wetlands are gone.
• Proportion of endangered and threatened species
  is higher than in any of the other lower 48
  states.
• Sewage systems are nearing capacity
• Water shortages from drought are threatening
  water supplies especially in southern CA.
• Irrigated cropland is losing productivity because
  of salinization.
• Air pollution from urban areas costs CA farmers
  100 million per year to damaged and lost crops.
• Despite the strictest air pollution standards,
  83 increase in motor vehicles and 150 increase
  in the total annual distance vehicles traveled
  between 1071 and 1995.

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What Factors Affect Birth Rates And Fertility
Rates?

• Average level of education and affluence.
• birth and fertility rates lower in developed
  countries where levels of education and affluence
  are higher
• Importance of children as part of the labor
  force.
• rates higher where children begin working at an
  early age
• Urbanization.
• People living in cities have better access to
  family planning services

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• Cost of raising and educating children.
• birth rates lower where raising children is more
  costly because children do not enter the labor
  force until they are in their 20s
• Education and employment opportunity for women.
• birth rate lower where women have access to
  education and paid employment outside the home.
• Infant mortality rate.
• people tend to have fewer children in countries
  where because fewer children die at an early age.

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• Average age at marriage.
• Women normally have fewer children when their
  average age at marriage is 25 or older.
• Availability of private and public pension
  system.
• Pensions eliminate the needs of parents to have
  many children to help support them in old age.
• Availability of legal abortions.

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• Availability of reliable methods of birth
  control.
• Religious beliefs, traditions and cultural norm.
• Those religions that strongly oppose abortion
  and birth control have higher birth rates.

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What Factors Affect Death Rate?

• It is not that people suddenly started breeding
  like rabbits, its just that they stopped dying
  like flies.
• Infant mortality rate is down.
• Improvements of sanitation, Immunization
  programs, improvement in medical care, higher
  living standards.
• Safer water supply

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• Life expectancy has increased since 1965 to an
  average of 75 years in developed countries and 63
  years in developing countries.
• Mortality reflects the general level of nutrition
  and health care.
• Infant mortality is probably the single most
  important measure of a societys quality of life.

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• The US infant mortality rate was 7.0/1000, down
  from 16.1/1000 in 1971.
• 32 countries have lower rates in 1998.
• \Three factors keep the US infant mortality rate
  higher
• Inadequate health care for poor women during
  pregnancy and for their babies after birth
• Drug addiction among pregnant women
• High birth rate among teen women
• Babies born to teen women are more likely to have
  low birth weights.

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• Population movement between and within countries
  is usually desirable.
• Typically people move to areas of more economic
  opportunity.
• Receiving countries can benefit from labor force
  willing to do the jobs the citizens arent
  willing to do.
• This does create an economic burden as large
  numbers of unskilled workers move into a
  community.
• CA is considering not allowing babies of illegal
  aliens born in the US to obtain US citizenship to
  make illegal immigration less attractive.

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• Pyramid shaped population profiles indicate
  population momentum
• The population will continue to grow or 50-60
  years

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• Culture has much to do with the ultimate decision
  to have a large or very small family.
• As economic development occurs, human societies
  move from a primitive population stability (high
  birthrate, high infant and childhood mortality)
  to a more modern population stability (low
  birthrate, low infant and childhood mortality)

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• What are the flaws in assuming that populations
  will stabilize as democratization, globalization
  and free enterprise occurs?
• Demographic transition occurs over many decades,
  not over night.
• Many of the most populous countries still very
  far behind the developed counties
• Present stresses are due to the 965 million with
  consumption oriented lifestyles.
• The assumption that development and changing
  birth rates does not prove that development is
  necessary for the demographic transition to occur.