1. HUMAN POPULATION DYNAMICS

2. Is the World Overpopulated?
Much of the world’s population growth occurs in developing countries like China and India.
The world’s population is projected to increase from 7 billion to 10.8 billion by 2050.
Fig. 6-1, p. 125

3. Five Most Populous Countries, 2010 and 2050
Figure 6.4: This chart shows the populations of the world’s five most populous countries in 2010 and 2050 (projected). In 2010, more than one of every three persons on the earth lived in China (with 19% of the world’s population) or India (with 17%). (Data from United Nations Population Division)
Fig. 6-4, p. 127

4. Is the World Overpopulated?
Some argue that the planet has too many people.
Some feel that the world can support billions of more people due to technological advances.
Constant debate over the need to reduce population growth.
Must consider moral, religious, and personal freedom.
Do not know how long we can continue increasing the earth’s carrying capacity for humans. Likely to be between billion people on earth by 2050.
97% of growth in developing countries living in acute poverty.

5. Limits on Population Growth
No population can increase its size indefinitely.
As the human population grows, so does the global total human ecological footprint
Cultural carrying capacity
Total number of people who could live in reasonable freedom and comfort indefinitely, without decreasing the ability of the earth to sustain future generations

6. Population Growth Cycle
Biotic potential– a populations capacity for growth
As a population levels off, it fluctuates slightly above and below the carrying capacity.
Biotic Potential ex. Housefly can lay 120 eggs in each generation. If nothing hurt the eggs or the flies, in 7 generations there would be 6,182,442,727,320 flies.

7. Humans Are Not Exempt from Nature’s Population Controls
Ireland
Potato crop in 1845
Bubonic plague
Fourteenth century
AIDS
Global epidemic

8. Exceeding Carrying Capacity: Move, Switch Habits, or Decline in Size
Over time species may increase their carrying capacity by developing adaptations.
Some species maintain their carrying capacity by migrating to other areas.
So far, technological, social, and other cultural changes have extended the earth’s carrying capacity for humans.

9. Features of Populations
Populations are dynamic and exhibit attributes that are not shown by the individuals themselves.
These attributes can be measured or calculated and include:
Population size: the total number of organisms in the population.
Population density: the number of organisms per unit area.
Population distribution: the location of individuals within a specific area.

10. Features of Populations
Population composition provides information relevant to the dynamics of the population, i.e. whether the population is increasing or declining.
Information on population composition (or structure) includes:
Sex ratios: the number of organisms of each sex.
Fecundity (fertility): the reproductive capacity of the females.
Age structure: the number of organisms of different ages.

11. Population size is influenced by births…
Population Dynamics
The study of changes in the size and composition of populations, and the factors influencing these changes, is population dynamics.
Key factors for study include:
Population growth rate: the change in the total population size per unit time.
Natality (birth rate): the number of individuals born per unit time.
Mortality (death rate): the number of individuals dying per unit time.
Migration: the number moving into or out of the population.
Population size is influenced by births…
…and deaths

12. Migrating species may group together to form large mobile populations
Migration
Migration is the movement of organisms into (immigration) and out of (emigration) a population. It affects population attributes such as age and sex structure, as well as the dynamics of a population.
Populations lose individuals through deaths and emigration.
Populations gain individuals through births and immigration.
Net Migration = Immigration – Emigration
Net Migration rate = Number of Immigrates/ Number of people in population.
Wildebeest - land based migration
Canada geese - aerial migration
Migrating species may group together to form large mobile populations

13. Population Density
Population Density - number of individuals per unit area or volume.
Can affect how rapidly a population can grow or decline. Ex. Biotic factors like disease.
Some population control factors are not affected by population density. Ex. Abiotic factors like weather.
At low densities, individuals are spaced well apart. Exs: territorial, solitary mammalian species such as tigers.
At high densities, individuals are crowded together. Examples: colonial animals, such as rabbits, corals, and termites.
Low density populations (
population )
= Population Density
area
High density populations

14. Population Distribution
A crude measure of population density tells us nothing about the spatial distribution of individuals in the habitat.
The population distribution describes the location of individuals within an area.
Distribution patterns are determined by the habitat patchiness (distribution of resources) and features of the organisms themselves, such as territoriality in animals or autotoxicity in plants.
Individuals in a population may be distributed randomly, uniformly, or in clumps.
Clumped distribution in termites
More uniform distribution in cacti

15. Spider populations appear to show a random distribution
A population’s distribution is considered random if the position of each individual is independent of the others.
Random distributions are not common; they can occur only where:
The environment is uniform and resources are equally available throughout the year.
There are no interactions between individuals or interactions produce no patterns of avoidance or attraction.
Random distributions are seen in some invertebrate populations, e.g. spiders and clams, and some trees.
Spider populations appear to show a random distribution

16. Saguaro cacti compete for moisture and show a uniform distribution
Uniform or regular distribution patterns occur where individuals are more evenly spaced than would occur by chance.
Regular patterns of distribution result from intraspecific competition amongst members of a population:
Territoriality in a relatively homogeneous environment.
Competition for root and crown space in forest trees or moisture in desert and savanna plants.
Autotoxicity: chemical inhibition of plant seedlings of the same species.
Saguaro cacti compete for moisture and show a uniform distribution

17. Sociality leads to clumped distribution
Clumped distributions are the most common in nature; individuals are clustered together in groups.
Population clusters may occur around a a resource such as food or shelter.
Clumped distributions result from the responses of plants and animals to:
Habitat differences
Daily and seasonal changes in weather and environment
Reproductive patterns
Social behavior
Sociality leads to clumped distribution

18. Density Dependent Factors
Density dependent factors exert a greater effect on population growth at higher population densities. At high densities, individuals:
Compete more for resources.
Are more easily located by predators and parasites.
Are more vulnerable to infection and disease.
Density dependent factors are biotic factors such as food supply, disease, parasite infestation, competition, and predation.
Competition increases in crowded populations
The intrinsic rate of increase (r) is the rate at which a population would grow if it had unlimited resources. Carrying capacity (K): the maximum population of a given species that a particular habitat can sustain indefinitely without degrading the habitat.
Parasites can spread rapidly through dense populations

19. Density Independent Factors
The effect of density independent factors on a population’s growth is not dependent on that population’s density:
Physical (or abiotic) factors
temperature
precipitation
humidity
acidity
salinity etc.
Catastrophic events
floods and tsunamis
fire
drought
earthquake and eruption
Factors that are not a part of the growing population. These factors are beyond the control of the organism and are usually result of the environment.

20. (Births – Deaths) + (Immigration – Emigration)
Population Growth
Population growth depends on the number of individuals added to the population from births and immigration, minus the number lost through deaths and emigration.
This can be expressed as a formula:
Crude birth and Crude death rates used which is #live births per 1000 per year and # of deaths per 1000 per year
Population growth =
(Births – Deaths) + (Immigration – Emigration)
(B)
(D)
(I)
(E)

21. Growth rate Global population growth rate
(Birth rate-death rate)/10
National population growth rate
(Birth rate-death rate) + (immigration – emigration) / 10
If a population of 10,000 experiences 100 births, 40 deaths, 10 immigrants and 30 emigrants in a year, what is the national population growth rate?

22. Annual Rate of Natural Population Change (%)=
Birth rate – Death rate
1,000 people x 100

23. Rates of Population Change
Ecologists usually measure the rate of population change. These rates are influenced by environmental factors and by the characteristics of the organisms themselves.
Rates are expressed as:
Numbers per unit time, e.g live births per year
Per capita rate (number per head of population), e.g. 122 live births per individuals (12.2%)
Many invertebrate populations increase rapidly in the right conditions
Large mammalian carnivores have a lower innate capacity for increase

24. Colonizing Population Population numbers (N)
Exponential Growth
Populations becoming established in a new area for the first time are often termed colonizing populations.
They may undergo a rapid exponential (logarithmic) increase in numbers to produce a J-shaped growth curve when plotted over time.
Exponential growth- growth that increases at a constant rate per unit of time. Ex. - the growth sequence 2, 4, 8, 16, 32, 64 and so on
In natural populations, population growth rarely continues to increase at an exponential rate.
Factors in the environment, such as available food or space, act to slow population growth.
Colonizing Population
Here the number being added to the population per unit time is large.
Exponential (J) curve Exponential growth is sustained only when there are no constraints from the environment.
Population numbers (N)
For example the common housefly can lay 120 eggs in each generation. If nothing hurt the eggs or the flies, in 7 generations there would be 6,182,442,727,320 flies.
Here, the number being added to the population per unit time is small.
Lag phase
Time

25. Logistic Growth Model
As a population grows and it encounters environmental resistance, its increase will slow, and it will stabilize at a level that can supported by the environment.
This type of sigmoidal growth (S) produces the logistic growth curve when plotted over time.
Established Population
The population encounters resistance to exponential growth as it begins to fill up the environment. This is called environmental resistance.
Carrying capacity (K)
The maximum population density that can be supported by the environment on a long term basis.
Environmental resistance increases as the population overshoots K.
Logistic (S) curve
As the population grows, the rate of population increase slows, reaching an equilibrium level around the carrying capacity.
Population numbers (N)
Populations grow rapidly with ample resources, but as resources become limited, its growth rate slows and levels off. As a population levels off, it often fluctuates slightly above and below the carrying capacity. The intrinsic rate of increase (r) is the rate at which a population would grow if it had unlimited resources. Carrying capacity (K): the maximum population of a given species that a particular habitat can sustain indefinitely without degrading the habitat.
Environmental resistance decreases as the population falls below K.
The population tends to fluctuate around an 'equilibrium level'. The fluctuations are caused by variations in the birth rate and death rate as a result of the population density exceeding of falling below carrying capacity.
In the early phase, growth is exponential (or nearly so)
Lag phase
Time

26. Exponential and Logistic Population Growth: J-Curves and S-Curves

27. Population overshoots carrying capacity Carrying capacity
2.0
Population overshoots carrying capacity
Carrying capacity
1.5
Population recovers and stabilizes
Population runs out of resources
and crashes
Number of sheep (millions)
1.0
Exponential growth .5
Figure 5.15: This graph tracks the logistic growth of a sheep population on the island of Tasmania between 1800 and After sheep were introduced in 1800, their population grew exponentially, thanks to an ample food supply and few predators. By 1855, they had overshot the land’s carrying capacity. Their numbers then stabilized and fluctuated around a carrying capacity of about 1.6 million sheep.
Populations grow rapidly with ample resources, but as resources become limited, its growth rate slows and levels off.
1800
1825
1850
1875
1900
1925
Year
Fig. 5-15, p. 115

28. Life Tables
Numerical data collected during a population study can be presented as a table of figures called a life table.
Life tables provide a summary of mortality for a population. The basic data are the number of individuals surviving to each age interval. This gives the ages at which most mortality occurs in a population.
Life table for a population of the barnacle Balanus
Age (yr)
No. alive at the start of the age interval
Proportion of original no. surviving at the start of the age interval
No. dying during the age interval
Mortality (d)
142
1.000 80
0.563 1 62
0.437 28
0.452 2 34
0.239 14
0.412 3 20
0.141 5
0.250 4 15
0.106
0.267 11
0.078
0.454 6
0.042
0.667 7
0.014
0.000 8 9
0.0 –

29. Number of survivors (log scale)
Survivorship Curves
The age structure of a population can represented with a survivorship curve. Survivorship curves use a semi-log plot of the number of individuals surviving per 1000 in the population, against age.
Because they are standardized (as number of survivors per 1000), species with different life expectancies can be easily compared.
The shape of the curve reflects where heaviest mortality occurs:
Type I: late loss
large mammals
Type II: constant loss
small mammals, songbirds
Number of survivors (log scale)
Type III: early loss
oysters, barnacles
Relative age

30. Type I Survivorship Curves
Species with Type I or late loss survivorship curves show the heaviest mortality late in life. Mortality is very low in the juvenile years and throughout most of adult life.
Late loss curves are typical of species that produce few young and care for them until they reach reproductive age.
Such species are sometimes called K- selected species and include elephants, humans, and other large mammals.
Mortality is very low in early life
Mortality increases rapidly in old age

31. Type II Survivorship Curves
Species with Type II or constant loss survivorship curves show a relatively constant mortality at all life stages.
Constant loss curves are typical of species with intermediate reproductive strategies. Populations face loss from predation and starvation throughout life.
Examples include some many types of songbirds, some annual plants, some lizards, and many small mammals.
Constant mortality.
No one age class is any more susceptible than any other.

32. Type III Survivorship Curves
Species with Type III or early loss survivorship curves show the highest mortality in early life stages, with low mortality for those few individuals reaching a certain age and size.
Early loss curves are typical of species that produce large number of offspring and lack parental care.
Such species are r- selected species (opportunists), and include most annual plants, most bony fish (although not mouth brooders), and most marine invertebrates.
Population losses are high in early life stages
Mortality is low for the few individuals surviving to old age

33. Population numbers (N)
‘r’ and ‘K’ Selection
Two parameters govern the logistic growth of populations.
The intrinsic rate of natural increase or biotic potential. This is the maximum reproductive potential of an organism, symbolized by the letter r.
The saturation density or carrying capacity of the environment, represented by the letter, K.
We can characterize species by the relative importance of r and K in their life cycles.
K-selected species
These species exist near asymptotic density (K) for most of the time. Competition and effective use of resources are important.
Population numbers (N)
r-selected species
These species rarely reach carrying capacity (K). Their populations are in nearly exponential growth phases for much of the year. Early growth, rapid development, and fast population growth are important.
Time

34. K-Selected Species
Correlates of K-selected species
Species that are K- selected exist under strong competition and are pushed to use available resources more efficiently.
These species have fewer offspring and longer lives. They put their energy into nurturing their young to reproductive age.
K-selected species include most large mammals, birds of prey, and large, long-lived plants.
Climate
Fairly constant and/or predictable
Mortality
Density-dependent
Survivorship
Usually types I and II
(late or constant loss)
Population size
Fairly constant in time. Near equilibrium with the environment.
Competition
Usually keen. Specialist niche.
Selection favors
Slower development, larger body size, greater competitive ability, delayed reproduction, repeated reproductions
Length of life
Longer (> one year)
Leads to:
Efficiency

35. r-Selected Species
Species with a high intrinsic capacity for population increase are called r- selected or opportunistic species.
These species show certain life history features and, to survive, must continually invade new areas to compensate for being displaced by more competitive species.
Opportunists include algae, bacteria, rodents, many insects, and most annual plants.
Correlates of r-selected species
Climate
Variable and/or unpredictable
Mortality
Density-independent
Survivorship
Often type III
(early loss)
Population
size
Fluctuates wildly. Often below K.
Competition
Variable, often lax. Generalist niche.
Selection
favors
Rapid development, high rm, early reproduction, small body size, single reproduction (annual)
Length of life
Short, usually less than one year
Leads to:
Productivity

36. Demography
Demography is the study of human populations, their characteristics and changes. Demographics will measure:
Statistics about people, such as births, deaths, and where they live as well as total population size.
GO TO census.gov and obtain the current world population and the current US population.

37. Science Focus: Projecting Population Change
Why range of billion for 2050?
Demographers must:
Measure statistics about people, such as birth, deaths, and where they live as well as total population size.
Determine reliability of current estimates
Make assumptions about fertility trends
Deal with different databases and sets of assumptions

38. Human Population Growth
The world population, now over 7.1 billion, is growing at the rate of about 80 million per year.
Projections put the world population at between 8 and 12 billion in 2050, with nearly all of this growth expected in the developing world.
Developing countries include: Africa, Asia, Latin America, the Caribbean, and regions of Melanesia, Micronesia, and Polynesia.
The human population has grown rapidly because of the expansion of agriculture and industrial production and lower death rates from improvements in hygiene and medicine.
The debate over interactions among population growth, economic growth, politics, and moral beliefs is one of the most important and controversial issues in environmental science.
Developing countries grew at 1.5% (15 times faster)
Developed countries grew at 0.1%

39. Growth Rate and percent change
Growth rate includes the birth rate, death rate, immigration and emigration. Usually calculated using the formulas:
Change in pop = (B+I) – (D+E)
% change = change in value/old value x 100%
If a population of 10,000 experiences 100 births, 40 deaths, 10 immigrants and 30 emigrants in a year, what is the annual percentage growth rate?
( ) – ( ) = 40
40/10,000 x 100% = 0.4%

40. Doubling Time: Rule of 70
Doubling time is the time it takes for the population to double the number of people in the current population. Calculated as 70 / % growth rate
70/ growth rate = doubling time
If a population of a country grows at a rate of 5% a year, the number of years required for the pop to double is what?

41. Doubling Time: Rule of 70 Growth Rate (% per year)
Doubling Time in years
0.1
700
0.5
140 1 70 2 35 3 23 4 18 5 14 6 12 7 10

42. Global Population Growth
Estimates of likely future growth of the world human population are highly uncertain and projections for 2050 range from a low of 7.7 billion to a high of 11.2 billion.
Global Human Population Growth
High fertility rate: 11.2 billion
Medium fertility rate: 9.4 billion
Low fertility rate: 7.7 billion
North America
Latin America & Caribbean
Europe
Asia & Oceania
Africa
Note: The latest ‘medium variant’ U.N. projection of 9.37 billion is nearly 500 million (4.7%) lower than the 9.83 billion projected in 1994.

43. Demographic Transitions
Process where countries become economically developed then their birth and death rates begin to decline. In the past this was referred to as “first” and “third” world countries or “developed” and “developing”.
Currently this process is described by the different stages according to population growth:
Preindustrial stage shows little population growth due to high birth rate with high death rate.
Transitional stage is where industrialization begins, death rates drops and birth rates remain high. Rapid population growth occurs.
Industrial stage is birth rate dropping and approaching death rate. Population growth slowly declines.
Postindustrial stage are birth rate and death rate become similar and population growth slows or declines.
Post-industrial: 37 countries have reached this stage. (mainly in W. Europe) To most population experts, the challenge is to help the remaining 88% of the world to get to this stage.

44. Demographic Transition
97% of growth in developing countries living in acute poverty usually occurs during the transitional stage.
What is the optimum sustainable population of the earth based on the cultural carrying capacity?
Generalized model of demographic transition shows that the total fertility of a society decreases as the society progresses through the demographic transition.
Some developing countries may have difficulty making the demographic transition.

45. Demographic Transition
Post-industrial: 37 countries have reached this stage. (mainly in W. Europe) The challenge is to help the remaining 88% of the world to get to this stage.
initially birth rate and death rate are both high, birth rate remains high, death rate declines (because of better health care, etc.), birth rate declines and approaches death rate (mention of postindustrial phase with explanation is acceptable).

46. Size/age classes in fish
Age Structure
Age structure refers to the number of organisms of different ages.
Populations can be broadly grouped into those individuals of:
pre-reproductive age
reproductive age
post reproductive age
Analysis of the age structure of populations can assist in their management because it can indicate where most population mortality occurs and whether or not reproductive individuals are being replaced.
Size/age classes in fish

47. Human Age Structure
Human age structure varies from country to country.
Number of people younger than age 15 is the major factor determining a country’s population growth.
In developing countries age structure tends to be in favor of younger individuals with a large proportion being under 15 years.
In developed nations, age structure is relatively even throughout the age groups.
Age Structure in Human Populations
Changes in distribution of a country’s age groups have long-lasting economic and social impacts.

48. Determining Population Growth
The rate at which a population grows or declines depends on its age structure.
Age structure diagrams show the distribution of different age groups. These groups are further broken into cohorts:
Prereproductive age (0-14) are persons who are not mature enough to reproduce
Reproductive age (15-44)are those persons that are capable of reproduction.
Postreproductive age (45+) are those persons too old to reproduce.

49. Age Structure Diagrams: Histograms
Populations with a large proportion of its people in the preproductive ages 1-14 have a large potential for rapid population growth. Those with a large proportion of people in reproductive age are experiencing rapid population growth.

50. Age Structure
Since age structure diagrams are broken down by age, demographers can obtain:
Birth rate
Maturity rate
Death rate of an entire population.
These diagrams are usually broken down by country and divided into genders.
29% of the people in developing countries were under 15 years old in 2012 versus only 16% in developed countries.
Changes in the distribution of a country’s age groups have long-lasting economic and social impacts.

51. Age Structure: United States
Today, baby boomers make up nearly half of all adult Americans and dominate the populations demand for goods and services.
Because of baby boom, the US has a bulge(yellow) in the pyramid with people in their 50’s-60’s.
There are more women than men in the older group because of differences in longevity between sexes.

52. Rapid Growth Diagram
A relatively large segment of the population of the country is currently in the prereproductive/reproductive years and will soon begin having children (giving the population momentum).
Pyramid shaped histograms have a birth rate that exceeds the death rate. Lower cohorts have more males and females.
Population growth is rapid in countries that have a pyramid shape.
Current modern examples include Africa, Asia, and Latin America

53. Slow/Stable Growth Diagrams
Birth rate exceeds the death rate. Population is getting larger. Pyramid shaped histogram.
In contrast, the prereproductive cohorts in county Y are about equal in size to the reproductive and postreproductive cohorts.
When the histogram shape is “box”-like, then stable or slow growth is represented.
Birth rate is almost equal to death rate. Sometimes called Zero growth.
Current examples of slow growth: USA, Australia, & Canada
Current examples of stable growth: Denmark, Austria, & Italy

54. Negative Growth Diagrams
Birth rate exceeds the death rate. Population is getting larger. Pyramid shaped histogram.
If there is declining or negative growth, then the birth rate with be less than the death rate.
Pyramids with declining populations tend to show larger numbers of older persons in their population.
Current examples: Germany & Japan

55. Slow decline manageable
Some Problems with Rapid Population Decline
Can threaten economic growth
Slow decline manageable
Rapid decline causes severe economic and social problems.
How do we pay for services for elderly?
Labor shortages
Less government revenues with fewer workers
Less entrepreneurship and new business formation
Less likelihood for new technology development
Figure 6.15: Rapid population decline can cause several problems. Question: Which three of these problems do you think are the most important?
Increasing public deficits to fund higher pension and health-care costs
Pensions may be cut and retirement age increased
Fig. 6-15, p. 138

56. Developing vs. Developed
Developing (Transitional, Third World):
Higher infant mortality rate because of a shortage in prenatal and pediatric care. Thus, they have more children to ensure some survive.
Agricultural societies need children to help in the labor force.
Lower per capita income or poorer countries need children to provide an income and sometimes contraceptives are not affordable.
Women lack education and job opportunities.
Developed (Industrial, First World):
Usually don’t have population problems but can be linked to poverty.
Educated and working women tend to delay childbearing.
Pension systems support people as they age.
Family planning and the ability to control fertility.
Higher cost of raising children causes people to have smaller families.
Abortion is legal.
Infant mortality higher in a country due to, for example, - contaminated drinking water - poor nutrition - poor health care- few or no educational opportunities for women.

57. Where Population Growth Occurred, 1950-2010
Figure 6.3: Most of the world’s population growth between 1950 and 2010 took place in the world’s less-developed countries. This gap is projected to increase between 2010 and (Data from United Nations Population Division, The 2008 Revision and Population Reference Bureau, 2010 World Population Data Sheet)
Fig. 6-3, p. 123

58. Urbanization
Urbanization is the movement of people from rural areas into cities
Urban areas must import most of its food, water, energy, minerals, & other resources because of large populations
Large populations produce and consume enormous quantities of resources that can pollute the air, water & land.
Disease can easily spread in urban areas because of the high density population.
44% of world’s people live in urban areas that occupy only 5% of world’s land and they consume 75% of the world’s resources.
50% of the world’s people live in urban areas that occupy only 5% of the world’s land & they consume 75% of the world’s resources.

59. Urbanization
Environmental pressures of urbanization from population growth are reduced because birth rates in urban areas usually are 3-4x’s lower than in rural areas because cities provide education opportunities.
Some countries, including China, penalize couples who have more than one or two children by:
Raising their taxes
Charging other fees
Eliminating income tax deductions for a couple’s third child
Loss of health-care benefits, free education, food allotments and job options
Thomas Malthus - “diminishing returns” He argues that rising wages and improved well-being would lead to excess reproduction among the working class. A labor surplus would then cause wages to fall below subsistence levels, resulting in starvation, disease and crime. In his view, land for food production was the limiting factor in both population growth and economic development.

60. Mortality and Fertility
Infant mortality rate: The number of child and/or infant deaths.
If a mother lives in an area with a high infant mortality rate she will tend to have a lot of children to ensure some will make it to adulthood. This ensures care for aging parents and a labor force.
Infant mortality rate is higher in developing countries than in developed countries.
Along with life expectancy, the infant mortality rate is a good indicator of the quality of life of a country
Replacement-level fertility: the number of children a couple must bear to replace themselves.
Slightly higher than two children per couple. (2.1 in developed countries and 2.5 in some developing countries.)
Infant mortality higher in a country due to, for example, - contaminated drinking water - poor nutrition - poor health care- few or no educational opportunities for women.

61. Total Fertility Rates
Fertility rate – number of children born to a woman during her lifetime.
Total fertility rate (TFR): the average number of children a woman has during reproductive years.
In 2012, the average global Total Fertility Rate was 2.4 children per woman.
1.6 in developed countries (down from 2.5 in 1950.)
3.0 in developing countries (down from 6.5 in 1950).
If fertility rate drops to replacement level fertility but the population continues to grow, this is called population momentum and can be seen in pyramid shaped age structure diagrams.
Birth rates and fertility rates have been slowed or decreased because:
Cultural/religious practices prohibited birth control.
Cultural/religious practices favored large families.
Education/Employment/Status of women is low
Reasons for decline from 1950 to present: increased/improved family planning shows fewer pregnancies, control of fertility, and choice in # of children.
Increased education of women/social status shows a delay in having children. Women enter the workforce and delay having children. Reduced need for children in the workforce because of industrialization and urbanization. Improved health care allows for more children to survive.

62. Fertility Rates
Based on current trends, it is assumed that human fertility rates will continue to decline and life expectancy will continue to increase. Developing countries are expected to broadly follow these demographic trends.
Trends in Fertility Rates
South & Central America
Africa
Asia
Developing
Developed

63. Where are we going? 11 10 World population (in billions) 9 8 7 6 2010
UN high-fertility variant (2008 revision)
U.S. Census Bureau (2008 update) 10
UN medium-fertility variant (2008 revision)
IIASA (2007 update)
UN low-fertility variant (2008 revision)
World population (in billions) 9 8 7
Figure 6.A: This graph shows world population projections to 2050 from three different organizations: the UN, the U.S. Census Bureau, and IIASA. Note that the upper-most, middle, and lower-most curves of these five projections are all from the UN, each assuming a different level of fertility. 6
2010
2020
2030
2040
2050
Year
Fig. 6-B, p. 130

64. Factors Affecting Birth Rates and Fertility Rates
The number of children women have is affected by:
The cost of raising and educating them.
Availability of pensions.
Urbanization.
Education and employment opportunities.
Infant deaths.
Child care
Marriage age.
Religious beliefs, politics, and cultural norms
Availability of contraception and abortion.

65. Factors Affecting Death Rates
Death rates have declined because of:
Increased food supplies, better nutrition due to
Green Revolution
Advances in medicine. (Antibiotics and vaccines)
Improvement in prenatal or neonatal care
Improved sanitation, safer water supplies and personal hygiene due to Industrial Revolution.
U.S. infant mortality is higher than it could be (ranked 49th world-wide by CIA and 30th by Save the Childeren) due to:
Inadequate pre- and post-natal care for poor.
Drug addiction.
High teenage birth rate.
Fertilizers and pesticides increased crop yields
More children live past childbirth

66. Infant Mortality Rates, 1950-2010
Figure 6.10: This graph tracks the infant mortality rates for the world’s more-developed countries and less-developed countries, 1950–2010, with projections to 2050 based on medium population projections. (Data from United Nations Population Division)
Fig. 6-10, p. 129

67. Populations Can Decline from a Rising Death Rate: The AIDS Tragedy
30 million killed:
Many young adults die: loss of most productive workers
Sharp drop in life expectancy
International community
Reduce the spread of HIV through education and health care
Financial assistance and volunteers
Fig. 6-15, p. 134

68. Population Stabilization
Human population growth is slower than predicted but because of the large and increasing population size the world population is still expected to increase substantially before stabilizing.
Progress Towards Population Stabilization
South & Central America
Africa
Asia
Developing
Developed

69. Demographics in the USA
The baby bust that followed the baby boom was largely due to delayed marriage, contraception, and abortion.
Now becoming senior citizens (Graying of America)
In 2012, the total fertility rate in the United States was slightly > 2.0

70. Demographics in the USA
Nearly 2.3 million people were added to the U.S. in 2012:
70% occurred because of births outnumbering deaths
30% came from illegal and legal immigration. Population increase in recent years has been because of immigration
TFR in U.S. dropped
Rate of population
growth has slowed.
Current US
Population:
320,367,731

71. Legal Immigration to the U.S. between 1820 and 2006
Figure 6.11: This graph shows legal immigration to the United States, 1820–2006 (the last year for which data are available). The large increase in immigration since 1989 resulted mostly from the Immigration Reform and Control Act of 1986, which granted legal status to certain illegal immigrants who could show they had been living in the country prior to January 1, (Data from U.S. Immigration and Naturalization Service and the Pew Hispanic Center)
Fig. 6-11, p. 135

72. 20th Century Lifestyle Changes in the U.S.
Figure 6.7: This chart lists some major changes that took place in the United States between 1900 and Question: Which two of these changes do you think were the most important? (Data from U.S. Census Bureau and Department of Commerce)
Fig. 6-7, p. 132

73. Developed Countries
High rates of resource use because of the availability of resources, production, and waste.
Result in high levels of pollution and environmental degradation per person because of control methods, clean up, and education.
The measure of a country’s economic growth is the Gross National Product (GNP) or the Gross Domestic Product (GDP).
The Human Development Index is also commonly used to determine development.
It is estimated that a US citizen consumes 35 X’s as much as the average citizen of India and 100 X’s as much as the average person in the world’s poorest countries. (What if everyone in the world lived like we do?) Then, poor parents in a developing country would need kids to have the same lifetime environmental impact as 2 US children.
Most developed countries have a GDP that is high and a population growth rate that is low.

74. Developing Countries
China, the largest, has taken drastic population control methods.
By 2050, India is predicted to pass China. Pakistan is projected to become 3rd (the US is 3rd now.)
Russia is losing 600,000 people a year, after being the 4th largest country in 1950 due to pollution, crime, corruption, hyperinflation, disease, and despair.
Environmentalists are concerned about resource use because developing countries are increasing their standard of living.
Russia’s declining population is because of environmental pollution, hyperinflation, crime, corruption, disease and despair.

75. Environmental Impact Equation (Paul Ehrlich Formula)
Population X affluence X technology = Environmental impact
Estimated that a US citizen consumes 35x’s as much as the average citizen of India and 100x’s as much as the average person in the world’s poorest countries.
Thus, poor parents in a developing country would need kids to have the same lifetime environmental impact as 2 typical US kids.

76. India’s Population Control
India has tried population control methods with modest success. Poor planning, bureaucratic inefficiency, low status of women and lack of support have led to low success. The family planning method calls for:
Education of women including basic literacy.
Encouraged education of contraception use among women & birth spacing.
Possible problems include:
Cultural/Social issues.
Cost of programs.

77. China’s Population Control
China has used a government-enforced program, “One-Child Policy”, to reduce the fertility rate. The One-Child Policy includes:
Paid leave to women for fertility operations.
Monthly Subsidy to one-child families.
Tuition and job priorities for only children.
Housing preferences.
Additional food rations.
Monetary compensation.
Problems include:
Preference toward gender
Increase in orphans
Consequences or punishment for multiple births
Since 1970, China has used a government-enforced program to cut its birth rate in half and sharply reduce its fertility rate.
- paid leave to women for fertility operations - monthly subsidy to single-child families - job priorities for only children - housing preferences for single-child families - additional food rations for one-child families - monetary compensation for single-child families

78. Core Case Study: Slowing Population Growth in China: A Success Story
1.35 billion people
Currently, China’s TFR is 1.5 children per women.
China has moved 300 million people out of poverty.
China’s policy penalizes couples who have more than one or two children by:
Raising their taxes, charging other fees, eliminating income tax deductions for a couple’s third child, and loss of health-care benefits, food allotments and job options

79. Illiteracy (% of adults) 47% 17% 36% Population under age 15 (%) 20%
Percentage of world
population
17%
India
20%
China
1.1 billion
Population
1.3 billion
Population (2050)
(estimated)
1.4 billion
1.6 billion
Illiteracy (% of adults)
47%
17%
36%
Population under age 15 (%)
20%
1.6%
Population growth rate (%)
0.6%
2.9 children per women (down from 5.3 in 1970)
Total fertility rate
1.6 children per women (down from 5.7 in 1972) 58
Infant mortality rate 27
Figure 9.15
Global connection: basic demographic data for India and China in (Data from United Nations and Population Reference Bureau)
62 years
Life expectancy
70 years
Percentage living
below $2 per day 80 47
$3,120
GDP PPP per capita
$5,890

80. 1994 Global (Cairo) Conference: Population & Development
The summit at Cairo, Egypt, encouraged action to stabilized the world’s population at 7.8 billion by 2050, instead of the projected billion.
Provide universal access to family-planning services
Improve the health care of infants, children & pregnant women and improve the status of women by expanding education & job opportunities
Encourage development of national population policies
Increase men’s involvement in child-rearing responsibility & family planning and increase access to education for girls
Take steps to eradicate poverty
STOP
Describe one incentive that the government of a country could offer its citizens that would favor a reduction in the growth rate of its population. Explain how this incentive would work, and describe one possible drawback.

81. INFLUENCING POPULATION SIZE
The best way to slow population growth is:
Investing in family planning(has reduced number of births and abortions throughout world).
Reducing poverty.
Education
Elevating the status of women by not suppressing their human rights and having paying job outside of home.
Family planning in less-developed countries
Responsible for a 55% drop in TFRs
Financial benefits: money spent on family planning saves far more in health, education costs
Women
Do most of the domestic work and child care
Provide unpaid health care
2/3 of all work for 10% of world’s income
Discriminated against legally and culturally

82. Global Contraceptive Usage
Two problems
42% pregnancies unplanned, 26% end with abortion
Many couples do not have access to family planning

83. Thomas Malthus 1798 Problems with a Growing Population
“diminishing returns” – Human population increases exponentially while food supplies increase at a slower linear rate
Argued rising wages and improved well-being would lead to excess reproduction among the working class.
A labor surplus would then cause wages to fall below subsistence levels, resulting in starvation, disease and crime.
Argued, land for food production was limiting factor in both population growth and economic development.

84. Problems with a Growing Population
Reasons for World Hunger Issues
Unequal distribution of available food
Loss of arable land
Increasing population growth rate
Increasing poverty in developing countries
Strategies for ensuring adequate nutrition for a growing population:
Increase the number of new food crops from a diversity of plant species
Distribute food more equitably
Increase land are that is dedicated to grain production rather than meat production
Assist developing countries in efficient crop irrigation systems.

85. Environmental Impact
Deforestation destroys habitats and reduces biodiversity:
Farming and the creation of monocultures, housing or development projects that cause urbanization, fuel from wood, and fossil fuel recovery from mining.
Fossil fuel burning releases CO2:
Results in climate change, change in temperature and precipitation patterns changing habitats.
Intensive fishing and fish farming:
Spreads disease to native fish and causes unsustainable fish populations.
Diversion and damming of water:
For agricultural, municipal, and industrial use reduces water supplies.
Building landfills:
To accommodate increased amounts of trash.

86. HUMAN ASPECTS ON NATURAL SYSTEMS
We have used technology to alter much of the rest of nature in ways that threaten the survival of many other species and could reduce the quality of life for our own species.