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Population Clockhttp://www.census.gov/main/www/popclock.html
The global population reached 6 billion in fall of 1999
Expansion of habitat Increased capacity in existing habitats Importing resources Improved sanitation and medicine Increase in agricultural technology
Availability of food and water Invasion of parasites, pathogens, or
disease Over-crowding Sudden Climate changes Pollution of air, soil and water If we do not take steps to control
population it is likely one of these factors will forcibly reduce our population for us!!
Population: number of persons Population change: increase in the
number of persons (per year) Growth rates: rate of change (per year)
includes births, deaths and immigration, and emigration
Crude Birth Rate (CBR)= number of births per 1000 population 1990: 24 Today: 21.3
Crude Death Rate (CDR)= number of deaths per 1000 population 1990: 9 Today: 8.93
Rate Natural Increase is % growth rate without migration
RNI = (crude birth rate – crude death rate) 10
1990: 1.5% Today: 1.4% growth rates have come down
Number of years in which a population doubles its size
Doubling time can be approximated using growth rates and the rule of 70
Doubling time (T) = ___70_____ % growth rate
Calculate Doubling Time Below rate: 1.4% doubling time = 50 years rate: 2.0% doubling time = ______ years rate: 0.5% doubling time= _______ years rate: -0.5% doubling time = _______years
Human Population Growth Per Year = 1.4% LEDC (least economically developed
country)=1.7% MEDC (more economically developed
country) = 1.0%
TFR (total fertility rate) = number of children born to a woman
during her reproductive years (or life time) 1990: 3.1 2000: 2.8
IMR (infant mortality rate) = infant deaths per 1000 live births (infant <
1 yr) Used as overall indicator of health 1990: 62 2000: 56 (1900: 200)
Use Ne(rt) formula N= Current population e= constant 2.71828… r = growth rate as a decimal!!! t = time in years
Example: 2010 data reports that a population of 2,350,000 has a growth rate of 1.2%. What will the population be in 2025?
The maximum population that can be sustainably supported without running out of resources.
MEDC’s LEDC’s
industrialized little or no industry
high GDP (gross domestic product)
low GDP
relatively rich populationprovide raw materials but few processed or manufactured goods
access to education and health care
limited access to education and health care
high resource use per capita
fewer resources consumed per person
low population growth ratesmost have high population
growth rates
Graphic device: bar graph Shows the age and gender composition
of a region Horizontal axis: gender
male: left-hand female: right-hand absolute number of people or %
Vertical axis: age 5-year or 10-year age groups
Three population categories Pre Reproductive- (0-14) Reproductive- (15-44) Post Reproductive- (45 +)
Helps to determine specifics of potential future populations
Shape of pyramid indicates future growth
Can point to future changes in social conditions of a country
StagePre-
industrial(Stage 1)
LEDC(Stage 2)
Wealthier LEDC
(Stage 3)
MEDC (Stage 4)
MEDC(Stage 5)
Birth rate
High High Declining Low Very low
Death rate
High Moderate Low Low Low
Life expect
Short Medium Long Long Long
Pop’l growth
Slow Rapid Slowing Stable Shrinking
Birth rates, death rates and growth rates systematically change through time as societies change: Modernize, urbanize Gain access to new technology Births, deaths, migration Fertility rates play huge role
Urbanization Importance of children in workforce Cost of raising a child Education/Employment for women Average age of marriage Availability of abortion Availability of birth control Religious beliefs, traditions and culture
High birth rates, high death rates, low growth rates
Stage for much of human history, traditional societies
Practically no country today
High birth rates, declining death rates, rising growth rates
Improvements in sanitation (water) and medicine
Europe during Industrial Revolution
LEDC countries since the 1950’s
Much of Africa today, some countries of Asia (Afghanistan, Nepal)
Continued decline of death rates, declining birth rates, growth rates decline from high to lower levels
Change in behavior: adaptation to lower death rate, in particular infant mortality rate
Economic change: urbanization (incentive to have fewer children)
Mexico today
Stage 4: low birth rates, low death rates, low growth rates United States today
Stage 5: low birth rates, rising death rates, declining growth rates (if birth rates drop below death rates: negative growth rates) Western Europe,
Japan
-500 -400 -300 -200 -100 0 100 200 300 400 500
0-4
5-9
10-14
15-19
20-24
25-29
30-34
35-39
40-44
45-49
50-54
55-59
60-64
65-69
70-74
75-79
80-84
85 OR
female
male
Stage 2: wide base
stage 3: wide middle
stage 4: slender
stage 5: narrow base
Computer simulations: Can be highly accurate with many variables Cant include unforeseen events (i.e. natural
disaster, terrorist strike, warfare)? Statistical and/or demographic tables
Include actual field measurements based on past trends.
Past trends may not always predict future trends. How large/representative are the sample
populations? Age/sex pyramids (
see above) Population curves
Mathematical extrapolation from graphs based on real data
Less complex than computer models