Topic 2

1
Topic 2 The Attributes of Populations

• A Population Growth
• B Fertility
• C Mortality
• D Population Profiles
• E Population Capacity

2
Fertility
A

• 1. Context
• 2. Growth Rates
• 3. Doubling Time

3
Context
1

• Definition
• Process during which the population of an area
  increases.
• Related to a complex economic, cultural and
  social environment.
• Two factors
• (1) Number of births exceeds the number of
  deaths.
• (2) Migration flow is positive.
• Expressed in percentages.
• Birth rate of 20 per 1000 people.
• Death rate of 10 per 1000 people.
• Growth rate of 10 people per year per 1000
  population, or 1.

Births minus Deaths
Positive migratory balance
Population Growth
Society
Economy
Culture
4
Top ten contributors to world population growth,
1995-2000
1
5
Context
1

• Reasons for huge population growth
• Achieved death control more effectively then
  birth control.
• Modern medicine
• Vastly decreased the number of deaths from many
  diseases (malaria, yellow fever, etc.).
• Famine
• Reduced through better agriculture, distribution,
  storage and by international aid mechanisms.
• Infant mortality
• Decreased in most areas.
• Improvement in the availability and quality of
  the water supply
• Improved hygiene conditions.
• Decreased deaths caused by water borne diseases.

6
Context
1

• Birth control has been more difficult to achieve
• Religious beliefs.
• Cultural traditions.
• The importance of children as help, labor and
  security.
• The role of women is very limited in many
  societies.

7
Growth Rates
2

• High growth
• 2 and above.
• Characteristic of many Third World countries.
• Average growth
• Between 1 and 2.
• Much of Latin America and parts of Asia,
  including China.
• Low growth
• Between 0 and 1.
• Europe, the United States and Canada are
  currently in this range.
• Zero population growth (ZPG)
• Less than 0.
• Several European countries.

High
2.0
Average
1.0
Low
0.0
ZPG
8
Population Growth Rate, 2000
2
9
Population Change between 2000 and 2050 ()
2
10
3 Scenarios of Global Population Growth, 2005-2050
2
11
Population of Russia, Japan Italy, 1950-2050 (in
millions)
2
12
Doubling Time
3

• Definition
• Length of time necessary for an area (usually a
  nation) to double its population.
• The mathematics of population work very much like
  compounding interest.
• Percentage of increase is applied to an
  ever-increasing base.
• Simple equation 72 / Growth rate.
• Implications
• The faster the growth rate the lower the doubling
  time
• 1 growth rate 72 years.
• 4 growth rate 19 years.
• Infinite doubling time no growth or negative
  growth.

13
Doubling Time as of 2000
3
14
Fertility
B

• 1. Crude Birth Rate
• 2. Total Fertility Rate
• 3. Factors Influencing Fertility

15
Crude Birth Rate
1

• Crude Birth Rate (CBR) or General Fertility Rate
  (GFR)
• Number of live births per year per 1000
  population.
• Both males and females are considered.
• All the population is considered, even the
  non-reproductive segment (children, elderly).
• Numbers like 10, 20, 40, etc.

25 males of any age
25 females of any age
10 children born that year
1,000
30
CBR 30
16
Total Fertility Rate
2

• Total Fertility Rate (TFR)
• Number of live births per female of reproductive
  age (15-49).
• Numbers such as 2.2, 4.5.
• Indicates population change over a long period of
  time.
• Instructive about societal norms in any given
  culture.
• A TFR of 2.1 is considered as being the
  replacement birth rate.
• Lower than 2.1 yields population decrease while
  rates greater than 2.1 yields population
  increase.
• Improvements in medical conditions lower the
  replacement rate (below 2.06 in many countries).

25 females between 15-49
10 children born that year
1,000
60
TFR 2.04 (60/1,000) (49-15)
17
Total Fertility Rate, 1994-2000
2
Replacement rate (2.1)
18
Total Fertility Rate, 2000
2
19
Factors Influencing Fertility
3
Biological Determinants
Social Determinants
Fertility
Economic Determinants
20
Factors Influencing Fertility
3

• Biological determinants
• Age
• Reproductive age of women ranges from 15-44 or
  from 15-49.
• Men 13-??
• Health and nutrition
• Poor health and/or nutrition can reduce
  fertility.
• Linked with underweight children.
• Linked with child mortality rates.
• Environment
• Represents an undocumented impacts on fertility.
• Stressed populations tend to have less males than
  females.
• Possible correlation between sperm count and
  pollution.

21
Birth Rate per Age Group, United States, 1965,
1990, 2002 (per 1,000 women)
3
22
Average Sperm Count of Americans, 1938-98 (per ml)
3
23
Factors Influencing Fertility
3

• Social determinants
• The social norms and acceptance of practices
  affecting fertility.
• Differ from society to society.
• Marriage
• Particularly the average age of marriage.
• The percentage of people never married varies
  spatially and affects fertility rates.
• Late marriage age generally involves less
  children.
• Contraception
• Used by 30-50 of all married couples.
• Availability of contraceptive devices and social
  attitudes toward their use affect fertility
  rates.
• Sharp differences exist between DCs and LDCs.
• Some notable exceptions, such as China and Cuba.

24
Factors Influencing Fertility
3

• Abortion
• Last resort measure when contraception failed (or
  was not used).
• Its legality is not universal and under challenge
  in some countries where it is permitted.
• Global figures (1999)
• 210 million pregnancies.
• 22 of all pregnancies end up in a abortion.
• 46.2 million abortions, of which 20 million
  procedures are obtained illegally.
• Illegal abortions are common in most societies
  where it is prohibited.
• Culture plays an important determining role in
  the impact of abortion.
• United States 49 all pregnancies unwanted and
  about half of unwanted pregnancies ended in
  abortion (1.4 million abortions per year).

25
Pregnancies and Abortions per Women Aged 15-19
Years, 1998
3
26
Factors Influencing Fertility
3

• Economic determinants
• The role of children, or their value affects
  fertility.
• Inverse relationships
• Fertility and income per capita.
• Fertility and urbanization.
• Traditional rural societies
• Children still play an important economic role
  and contribute to family wealth.
• Fertility is likely to remain higher.
• Industrial and post-industrial societies
• Costs tend to increase with the development level
  of the society.
• Deflate the fertility rate since parents must
  consider the direct and opportunity costs of
  bearing additional children.

27
Factors Influencing Fertility
3

• Direct costs lost
• For the support of children.
• Food, clothing, housing, education, etc.
• Opportunity costs lost
• Lower standard of living.
• Reduce the ability to save and invest.
• Labor force participation of women is affected by
  child-bearing.

28
Mortality
C

• 1. Crude Death Rate
• 2. Infant Mortality Rate
• 3. Life Expectancy

29
Crude Death Rate
1

• Death rate
• Easiest of the variables to consider.
• Occurs just once per person and is the most
  recorded.
• Crude Death Rate (CDR)
• Annual number of deaths per 1000 population (all
  ages included).

25 males of any age
25 females of any age
10 people who died that year
1,000
30
CDR 30
30
Crude Death Rate
1

• Causes of death
• Throughout most of history famine, epidemics, and
  wars have been the leading causes of death.
• Primary causes of death began to shift to
  degenerative problems related to aging.
• These include such factors as heart disease and
  cancer.
• Death and welfare
• Used to be considered a sign of the health of a
  population.
• Different age structures among the populations of
  different countries.
• Possible for a nation with high living standards
  to have a higher death rate than a poorer nation.
• Reason overall older population.

31
Crude Death Rate, 2000
1
32
Fertility and Mortality in the United States,
1950-2003 (in 1000s)
1
33
Infant Mortality Rate
2

• Definition
• Expressed in numbers of deaths of infants under
  one year per 1000 live births of the same year.
• Also considers the death of children under 5 per
  1000 in their cohort.
• High levels of infant mortality pull down life
  expectancy rates.
• Reflects the quality of the health system.
• Very strong differences between developed and
  developing countries.

34
Infant Mortality Rate, 2000
2
35
Causes of Death for Children under 5 in
Developing Countries
2
36
Life Expectancy
3

• Definition
• Number of years a person is expected to live.
• Based on current death rates.
• May change due to ameliorations in standards of
  living.
• Context
• Strong geographical variations in life
  expectancy.
• Half a century ago, most people died before the
  age of 50.
• Global average life expectancy reached 65 years
  in 2000.
• Several achievements and failures
• Economic development has benefited human health.
• Improvement in diet and sanitation.
• Urbanization may have adverse effects.

37
Life Expectancy at Birth, 1910 and 1998
3
38
World Average Life Expectancy and Life Expectancy
in Industrial and Developing Nations, 1950-2000
3
39
of Men and Women Expected to Survive to Age 80,
by Region (Among people born 1995-2000)
3
40
Yearly Cost of a 1,000,000 Life Insurance
Premium, 2001
3
41
Life Expectancy
3

• Optimum life expectancy
• Life expectancy is ultimately dictated by human
  physiology
• At some points, organs cease to function
  properly.
• Limit on the lifespan of non-cancerous human
  cells.
• Nearing life expectancy limits
• Even if age-related diseases such cancer, heart
  disease, and stroke were eradicated, life
  expectancy would only increase by 15 years.
• Currently around 76 years.
• Expected to reach 85 years in most developed
  countries by 2030.

42
Population Profiles
D

• 1. Population Pyramid
• 2. Dependency Ratio
• 3. Sex Structure

43
Population Pyramid
1

• Definition
• Graph showing the breakdown of each sex by age
  group (cohort).
• Illustrates a nations population structure.
• Shows the male/female composition of the
  population.
• Most of the time, the breakdown involves 5 years
  periods.

75
60-75
45-60
30-45
15-30
0-15
44
Population Pyramid of Mexico, 2000
1
45
Population Pyramid of Sweden, 2000
1
46
Population Pyramid
1

• Mexican pyramid
• Much wider base than the others.
• Beginning of transition.
• Rapidly growing population where the percentage
  of people under 15 years of age is high.
• Swedens pyramid
• Does not appear to be a pyramid at all.
• Youngest component is smaller than its
  middle-aged population and only slightly larger
  than its aged population.
• No-growth situation, since some deaths occur from
  all age groupings.
• Sweden has a higher death rate than Mexico.

47
Population Pyramid of the United States, 2000
1
48
Population Pyramid
1

• USA pyramid
• Intermediate situation
• Aging population.
• Large amounts of recent immigration.
• Bulge in the 30-54 year old component
• The baby boom generation.
• Small numbers in the 55-65 year old component
• Low birth rates during the 1930s and during WW
  II.
• Dip in 20-29 segment of the population
• Low birth rates during the 1970s and early 1980s.
• Limited immigration.
• Preponderance of women at the top of the pyramid,
  an indication of their longer average life span.

49
Population Pyramid, Berlin 1946
1
50
Population Pyramid
1

• German pyramid
• Shows the most extreme example of population
  decline.
• Vast difference between males and females in the
  upper age groups.
• Vast number of military casualties among the
  population which fought the WWII.
• Significant impacts in the post WWII labor market.

51
Dependency Ratio
2

• Definition
• Comparison between the productive and
  non-productive population.
• Often expressed in non-productive per 100
  productive.
• Non-productive population
• Refers to the very old (usually gt65 years of age)
  and the very young (usually lt15).
• Considered to be the non-productive segments of
  society because they are not part of the labor
  force.
• Productive population
• Between 15 and 65.
• This portion of the population constitutes the
  labor force.
• Revised to consider lower than 20 years in
  developed countries (increasing time spent for
  education).

52
Dependency Ratio
2

• Implications
• Society incurs costs in supporting its dependent
  population.
• Old age generates social costs
• Retirement benefits.
• Increased medical expenditures.
• USA 12 of the population over 65 accounting for
  60 of health care costs.
• Greater consumption of other social services.
• Youths
• Some medical costs.
• Great expenditures for education.
• National budgets often reflect these
  expenditures.
• Linked with the population pyramid
• Pyramidal distributions have high dependency
  ratios.
• Rectangular distributions have high dependency
  ratios.
• Transitional pyramids have low dependency ratios.

53
Dependency Ratio of some Countries, 1990-1999
(per 100)
2
54
Dependency Ratio
2

• Aging
• Major shift in health issues.
• 1995 380 million people aged 65 years and above.
• 2020 over-65 population is projected to increase
  globally by 82, to more than 690 million.
• For every baby born today in an industrialized
  country, there are 10 people aged 65 or over.
• By the year 2020 there will be 15 such elderly
  persons for each newborn.
• In developing countries, the ratio today is 2
  people over 65 for every newborn, and 4 for every
  newborn by 2020.

55
Population 60 and Over, Industrial and Developing
Countries, 1950-95, With Projections to 2050
2
56
Percentage of the Population between 15 and 65,
2000
2
57
Dependency Ratio
2

• Impacts
• Social security costs.
• Medical costs and the medical industry at large.
• Public sector funds such as the federal budget.
• Goods and services used by the elderly experience
  increasing demand levels.
• Those used by the young and/or middle aged will
  decline in relative importance.
• Local impacts (school districts).

58
Sex Structure
3

• Definition
• Gender composition of a population.
• Males / Females 100.
• Probability
• Approximately equal probability of male and
  female births.
• Normally expect sex ratios to remain very close
  to 100.
• This is often not the case.
• Factors
• Life expectancy at birth is greater for females
  (79 years) than for males (72).
• Gap has increased steadily since 1920, when the
  difference was just one year.

59
Sex Ratio (males per 100 females), 2000
3
60
Sex Ratio in the United States, 1820-2000 (males
per 100 females)
3
WWI
WWII
Civil War
Immigration Boom
Life expectancy gap
Immigration Boom
61
Population Capacity
E

• 1. Population Density
• 2. Population Distribution
• 3. Population Capacity

62
Population Density
1

• Arithmetic density
• Relates the size of a population (P) to the area
  which contains it (A).
• Number of people per square mile or square
  kilometer.
• Without regard to the productive quality of the
  area.
• Distributional imbalances.
• Physiological density
• Number of people per unit of productive land.
• Productive is generally equated with arable land
  (AL).
• Important figure to measure sustainability.

AD P / A
Arable land
PD P / AL
63
Density Measures for Selected Countries, 1995 (in
people per square mile)
1
64
Population Distribution
2

• Definition
• Considers the distribution of population
  densities over the earths surface.
• Informative in assessing a nations population.
• Typical concentrations along major river systems.
• Areas of great concentration
• South Asia.
• East Asia.
• Western Europe.
• Northeastern North America.
• Empty areas are attributed to
• Harsh physical landscapes.
• Harsh temperature.

65
World Population Density and Distribution, 1995
2
66
Population Capacity
3

• How many people can be sustained by the Earth?
• Based on human choices and natural constraints.
• Maximum density.
• Quantity of arable land.
• Agricultural technology.
• Harvesting the ocean.
• Human facilities.
• Availability of resources (energy, construction
  materials, etc.).

Space
Technology
Consumption
Resources
67
Population Capacity
3

• Demographic capacity
• Studies about natures capacity to support human
  life go back many centuries.
• Leeuwenhoek (1679) extrapolated densities for
  Holland to the whole planet (13.4 billion
  capacity).
• Focus
• Space.
• Energy requirements.
• Non-renewable resources.
• Photosynthetic potentials.
• All are based on the same principle
• Tracing resource and energy flows through the
  human economy.

68
Population Capacity
3

• Ravenstein in 1891
• Concept of carrying capacity.
• Focused on the earths cultivable areas, and
  their potential productivity given increases in
  yields over time
• Fertile 200 people / km2.
• Steppe 10 people / km2.
• Desert 1 person / km2.
• Figure of 6 billion people as the number Earth
  could sustain without lowering living standards.
• Reached this number in 1999.

Arable land
X
Agricultural technology
/
Consumption per capita
69
Population Capacity
3

• Contemporary issues
• Events such as the Green Revolution were not
  foreseen by Ravenstein.
• Managed to increase agricultural yields in many
  areas by quantities far greater than he had
  anticipated.
• Efforts to calculate carrying capacity have
  largely failed.
• Too many variables.
• Value ranges between 4 and 16 billion.

70
Population Capacity
3

• Level of consumption
• Alternative perspective.
• The issue is not resource supply, but resource
  demand.
• The world is producing only a finite number of
  resources for consumption.
• Demographic capacity is linked with level of
  resource consumption.
• American (lifetime)
• 1 million kg of atmospheric waste.
• 10 million kg of liquid waste.
• 1 million kg of solid waste.
• 700,000 kg of minerals.
• 24 billion BTU of energy.
• 25,000 kg of plants.
• 2,000 animals (28,000 kg).