Fertility1. Context2. Growth Rates3. Doubling TimeA

ContextDefinitionProcess 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%.1Population GrowthSocietyEconomyCultureBirths minus DeathsPositive migratory balance

Top ten contributors to world population growth, 1995-20001

ContextReasons for huge population growthAchieved 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.1

ContextBirth control has been more difficult to achieveReligious beliefs.Cultural traditions.The importance of children as help, labor and security.The role of women is very limited in many societies.1

Growth RatesHigh growth2% and above.Characteristic of many Third World countries.Average growthBetween 1 and 2%.Much of Latin America and parts of Asia, including China.Low growthBetween 0 and 1%. Europe, the United States and Canada are currently in this range.Zero population growth (ZPG)Less than 0%.Several European countries.2HighZPGAverageLow2.0%1.0%0.0%

Population Growth Rate, 20002

Population Change between 2000 and 2050 (%)2

3 Scenarios of Global Population Growth, 2005-20502

Population of Russia, Japan Italy, 1950-2050 (in millions)2

Doubling TimeDefinitionLength 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.ImplicationsThe 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.3

Doubling Time as of 20003

Fertility1. Crude Birth Rate2. Total Fertility Rate3. Factors Influencing FertilityB

Crude Birth RateCrude 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.125 males of any age25 females of any age1,00010 children born that year30CBR = 30

Total Fertility RateTotal 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).225 females between 15-4910 children born that year1,00060TFR = 2.04= (60/1,000) * (49-15)

Total Fertility Rate, 1994-20002Replacement rate (2.1)

Total Fertility Rate, 20002

Factors Influencing FertilityBiologicalDeterminantsSocialDeterminantsEconomicDeterminants3Fertility

Factors Influencing FertilityBiological determinantsAge: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.3

Birth Rate per Age Group, United States, 1965, 1990, 2002 (per 1,000 women)3

Average Sperm Count of Americans, 1938-98 (per ml)3

Factors Influencing FertilitySocial determinantsThe 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.3

Factors Influencing FertilityAbortion: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).3

Pregnancies and Abortions per Women Aged 15-19 Years, 19983

Factors Influencing FertilityEconomic determinantsThe 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.3

Factors Influencing FertilityDirect 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.3

Mortality1. Crude Death Rate2. Infant Mortality Rate3. Life ExpectancyC

Crude Death RateDeath rateEasiest 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). 125 males of any age25 females of any age1,00010 people who died that year30CDR = 30

Crude Death RateCauses of deathThroughout 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 welfareUsed 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.1

Crude Death Rate, 20001

Fertility and Mortality in the United States, 1950-2003 (in 1000s)1

Infant Mortality RateDefinitionExpressed 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.2

Infant Mortality Rate, 20002

Causes of Death for Children under 5 in Developing Countries2

Life ExpectancyDefinitionNumber of years a person is expected to live.Based on current death rates.May change due to ameliorations in standards of living.ContextStrong 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.3

Life Expectancy at Birth, 1910 and 19983

World Average Life Expectancy and Life Expectancy in Industrial and Developing Nations, 1950-20003

% of Men and Women Expected to Survive to Age 80, by Region (Among people born 1995-2000) 3

Yearly Cost of a $1,000,000 Life Insurance Premium, 20013

Life ExpectancyOptimum life expectancyLife 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 2030.3

Population Profiles1. Population Pyramid2. Dependency Ratio3. Sex StructureD

Population PyramidDefinitionGraph 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.10-1515-3030-4545-6060-7575+

Population Pyramid of Mexico, 20001

Population Pyramid of Sweden, 20001

Population PyramidMexican pyramidMuch wider base than the others.Beginning of transition.Rapidly growing population where the percentage of people under 15 years of age is high.Swedens pyramidDoes 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.1

Population Pyramid of the United States, 20001

Population PyramidUSA pyramidIntermediate 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.1

Population Pyramid, Berlin 19461

Population PyramidGerman pyramidShows 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.1

Dependency RatioDefinitionComparison between the productive and non-productive population.Often expressed in non-productive per 100 productive.Non-productive population:Refers to the very old (usually >65 years of age) and the very young (usually

Dependency RatioImplicationsSociety 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.2

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

Dependency RatioAgingMajor 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. 2

Population 60 and Over, Industrial and Developing Countries, 1950-95, With Projections to 20502

Percentage of the Population between 15 and 65, 20002

Dependency RatioImpactsSocial 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).2

Sex StructureDefinitionGender 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.FactorsLife 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.3

Sex Ratio (males per 100 females), 20003

Sex Ratio in the United States, 1820-2000 (males per 100 females)3Civil WarImmigration BoomWWIIWWILife expectancy gapImmigration Boom

Population Capacity1. Population Density2. Population Distribution3. Population CapacityE

Population DensityArithmetic densityRelates 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 densityNumber of people per unit of productive land.Productive is generally equated with arable land (AL).Important figure to measure sustainability. 1AD = P / APD = P / ALArable land

Density Measures for Selected Countries, 1995 (in people per square mile)1

Population DistributionDefinitionConsiders 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.2

World Population Density and Distribution, 19952

Population CapacityHow 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.).3SpaceResourcesTechnologyConsumption

Population CapacityDemographic capacityStudies 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.3

Population CapacityRavenstein in 1891Concept 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 1999.3Arable landAgriculturaltechnologyConsumptionper capitaX/

Population CapacityContemporary issuesEvents 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.3

Population CapacityLevel of consumptionAlternative 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).3

10 countries contributed to 59.8% of the annual growth of 77.7 millions between 1995 and 2000.

Source: United Nations Population Division, World Population Prospects: The 1998 Revision, forthcomingSource: United Nations, World Population Prospects: The 2000 Revision (New York: February 2001)Source: United Nations Population DivisionSource: UNFPA, 2000.Source: Center for Disease Control. http://www.cdc.gov/nchs/datawh/statab/unpubd/natality/natab99.htmAnother sign of deteriorating human health is a fall in sperm counts. Among men in the United States, average sperm counts per milliliter of semen have dropped from 120 million in 1940 to just under 50 million in 1998. Counts in the European countries indicate a similar decline. The principal explanation for this is the so-called endocrine disruption hypothesis, namely that chemicals in the environment act as "environmental estrogens." These imitators of this basic female hormone-found in plastics, pesticides, and industrial pollutants-may adversely affect male reproductive functioning, among other things. Quoted from a Saturday, May 29, 1999 press release. Source: Worldwatch Institute.Source: Durex Global Survey.Source: The Alan Guttmacher Institute. Nearly 1.4 million abortions in a year, with nearly half of all pregnancies unwanted. Source: Center for Disease Control.

About 80% of the deaths are from diseases that could have been treated.Source: Worldwatch Institute.

Source: United Nations Population Division, 2000Source: TIAA-CREF.Source: US Census Bureau, International Database

Source: US Census Bureau, International Database

Source: US Census Bureau, International Database

Source: WHO, 2000.Source: Worldwatch Institute.Source: US census bureauSource: Fellman, Getis, & Getis 1999.