1. Population Dynamics

2. Population Pyramid USA 2000

3. Population Pyramids - Kenya

4. Human Population Dynamics

5. Population Indicators
Population Size Infant Mortality
Growth Rate Life Expectancy
Crude birth rate Age Structure
Crude death rate Doubling Time
Fertility Access to contraceptives
Per capita spending on health care
HIV incidence
Number of Refugees
Female Literacy
Percent of population in urban areas

6. Exponential Population Growth
occurs when resources are not limiting
causes population size to increase faster & faster with time
cannot occur forever because eventually some factor limits population growth

7. The Nature of Population Growth
How do populations grow? What do you have to know?
Reproduction rate
Food supply
Habitat requirements
Example: Eagles since the end of DDT – 413 nesting pairs in 1968, over 8,000 nesting pairs today in lower 48 states

8. POPULATION DYNAMICS Some Population Growth Terms:
Exponential Growth - Growth as a percentage of the whole.
Biotic Potential - Potential of a population to grow in the absence of expansion limitations.
Carrying Capacity - Number of individuals that can be indefinitely supported in a given area without environmental degradation

9. The population change equation
Where
P(t) is population at time t
B(t) is birth rate (births/time)
D(t) is death rate (deaths/time)
I(t) is immigration rate, and
E(t) is emigration rate.
(Note: this is a “difference equation”.)

10. The Mathematics of Population Growth
Ignoring emigration and immigration, population is only affected by the number of births and deaths:
For those comfortable with calculus, this can be transformed into a differential equation: -

11. General Exponential Growth
If you solve the difference (or differential) equation from the previous slide, you get the exponential growth equation:

12. Exponential Growth Curve

13. Doubling Time
When you use this equation to calculate the doubling time, Td , you get:
Note: r = b-d, and is the net growth rate

14. Using Doubling Time
The annual growth rate in India is 1.3 % annually, while the annual growth rate in China is 0.7% annually. How long will each country take to double its population if current growth rates continue?
India will take 54 years to double, China will require 100 years to double. Remember to express “r” as a decimal: 1.3% is 0.013, 0.7% is 0.007

15. (r) Strategies (K) Strategies
Short life
Rapid growth
Pioneers, colonizers
Early maturity
Little parental care.
Little investment in individual offspring.
Long life
Slower growth
Late maturity
Fewer large offspring.
High parental care and protection.
High investment in individual offspring.

16. Growth to a Stable Population
Logistic Growth - Growth slows as the population approaches carrying capacity.

17. Limits to Growth

18. Boom and Bust Cycles Exponential growth is graphed as a J curve.
Carrying Capacity - Number of individuals that can be indefinitely supported in a given area.without environmental degradation
Overshoot - When a population surpasses the carrying capacity of its environment.
Dieback
Oscillations

19. Population Oscillations

20. Natural Boom and Bust Cycles

21. Birth & Death Rates Over Time
In developed countries decreases in death rates are being accompanied by decreases in birth rates over time.

22. Birth & Death Rates Over Time
In developing countries decreases in death rates have not been accompanied by as large of decreases in birth rates over time, leading to major population increase.

23. Demographic Transition
A generalized model of demographic transition (four stages):

24. Demographic Transition - stage 1
1) Preindustrial Stage: both birth & death rates are relatively high & approximately equal, such that the population does not increase, & the population size is small.

25. Demographic Transition - stage 2
2) Transitional Stage: death rate decreases markedly because of industrialization, increased food production, & improved health care; birth rates remain relatively high, such that the population grows rapidly.

26. Demographic Transition - stage 3
3) Industrial Stage: birth rate drops & eventually approaches a balance with death rate, leading to a slowing of population growth.

27. Demographic Transition - stage 4
4) Postindustrial Stage: birth rate & death rates approximately balance, zero population growth is attained, & the population stabilizes at a size much higher than the preindustrial size; if birth rate declines below death rate negative population growth may even be attained.

28. Is the Demographic Transition a Universal Process?
Documented in US, Canada, Japan, and many European countries over the past years
May not happen in many developing countries
Role and freedoms of women
Value of children
Lack of resources may limit transition

29. Case Study: India Population Control in India:
in 1952 India began the first national family planning program;
the program has been disappointing because of poor planning, inefficiency, low status of women, extreme poverty, & lack of funds;
couples still have an average of 3.5 children because of the belief that they need children to work & care for them in old age.
India was the first country to establish a family planning program.

30. Case Study: China Population Control in China:
Since 1970, China, with the world's largest population, has initiated efforts to better feed its people & control population growth;
strict population control measures prevent couples from having more than one child;
although considered coercive, the policy is significantly slowing population growth.
Family planning programs can have three different policy motivations: reduce population growth (a demographic policy), improve women’s health (a health related policy), or provide reproductive rights (a human rights policy). (The quote below is from
“Concern with the macro-level, or national-level, consequences of rapid population growth on economic productivity, savings and investment, natural resources, and the environment—the “demographic” rationale—was the predominant rationale for much of the late 1960s and 1970s.
During the 1980s, a shift toward the health rationale occurred (driven by the consequences of high fertility for maternal, infant, and child mortality). As will be discussed, this shift occurred in part because of political,ideological, and scientific influences. Among these were that the health rationale was more appealing to policymakers in many countries, including those in sub-Saharan Africa.
In the 1990s, the human rights rationale became predominant, with its focus on women’s rights, principally reproductive rights, and the reproductive health of women and men. This most recent shift toward reproductive rights as a human right is associated with the United Nations International Conference on Population and Development (ICPD), held in Cairo in 1994.”

31. Human fertility: 1975 top, 2005 bottom

32. Three Viewpoints of Population Growth
People are the “ultimate resource” and no evidence suggests that population growth is a problem (Julius Simon)
Human population growth is increasing exponentially while food production is not, leading ultimately to starvation, crime, and misery (Thomas Malthus)
“There is enough for everyone’s need, but not enough for anyone’s greed” (Mohandas Gandhi) The problem is inequality in distribution of wealth and resources, and in use of resources per person

33. How can we reduce population growth?
Improve social, educational, and economic status of women
Improve status of children
Accept choice as a valid element in life in general and family planning in particular
Improve social security and political stability
Improve knowledge of, and access to safe, effective birth control
Encourage development of national population policies
Family planning programs have made a difference. Nearly 400 million women in developing countries use family planning to prevent unintended pregnancies. In the last 30 years the percentage of couples in developing countries using contraception has risen fivefold, from less than 10% in the 1960s to over 50% today (202). Fertility has dropped from an average of about six children per woman in the 1960s to about four today (47). (By comparison, in countries that have completed the transition from high to low fertility, about 70% of married women of reproductive age use contraception, and the average couple has about two children.)

34. Women’s education and fertility

35. Leading AIDS rates Botswana 38.8% Zimbabwe 33.7% Swaziland 33.4%
Namibia 22.5%
Zambia 21.5%
South Africa 20.1%
Lesotho 18.1%

36. Population profile of Botswana