Human PopulationHuman Population:: Growth, Demography and Carrying Capacity Growth, Demography and Carrying Capacity
Current World PopulationGlobal population was 6,629,514,472
On November 7, 2007 at 08:05 pm
• The global population grows by: – Nearly 2.3 persons per seconds
– Nearly 8,343 persons per hour
– Over 200,234 persons per day
– Over 73 million persons per year
Human Population DynamicsHuman Population Dynamics
There are just three sources of change in population size —
Fertility – number of children born Mortality -"natural decrease" refers to
population decline resulting from more deaths than births
Migration - Net migration is the number of immigrants minus emigrants
Human Population DynamicsHuman Population DynamicsReplacement fertility rate (RFR)
– The number of children a couple must have to replace themselves
Total fertility rate (TFR)– The average number of children born to a
woman during childbearing years (15-49)– Average in developed countries = 1.6 (1950 2.5)– Average in developing countries = 3.1 (1950: 6.5)
Infant Mortality Rate (IMR )
• infant deaths per 1000 live births (infant < 1 yr)– 1990: 62 now: 52 (normal in 1900: 200)– Current US IMR: 6.9% (69/1000)
Maternal Deaths per 100,000 Live BirthsMaternal Deaths per 100,000 Live Births
Source: WHO, UNICEF, UNFPA Maternal Mortality in 1995: Estimates Developed
by WHO, UNICEF AND UNFPA, 2001.
• Overall, the world population is growing at a rate of about 1.7%; if this rate continues, the population will double in 42 years.
Population PyramidsPopulation Pyramids• 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
Population Pyramid with Population Pyramid with young cohortsyoung cohorts
-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
Population PyramidsPopulation Pyramids
• High Growth: Afghanistan• Moderate Growth: Mexico
• Zero Growth: U.S.
• Negative Growth: Austria or Italy
Population PyramidsPopulation Pyramids• Population Pyramids on the Web
• High Growth: Afghanistan
• Moderate Growth: Mexico • Zero Growth: U.S.
• Negative Growth: Austria or Italy
Population PyramidsPopulation Pyramids• Population Pyramids on the Web
• High Growth: Afghanistan
• Moderate Growth: Mexico
• Zero Growth: U.S. • Negative Growth: Austria or Italy
Population PyramidsPopulation Pyramids• Population Pyramids on the Web
• High Growth: Afghanistan
• Moderate Growth: Mexico
• Zero Growth: U.S.
• Negative Growth: Italy
• Movement of a nation from high population growth to low population as it develops economically
• Transition as a result of four stages– Stage 1—Birth and death rates are both high– Stage 2—Death rates fall; birth rates remain high;
growth rate rises– Stage 3—Birth rates fall as standard of living
rises; growth rate falls– Stage 4—Growth rate continues to fall to zero or
to a negative rate
Demographic TransitionDemographic Transition
Population Pyramids and Population Pyramids and Demographic StagesDemographic Stages
• characteristics shapes of ‘pyramids’– wide base (true pyramid)– wide middle (bulge), somewhat wider base– urn- or bottle-shaped– reversed pyramid
• different shapes--different dynamics
Population Pyramid and Demographic TransitionPopulation Pyramid and Demographic Transition• Stage 2: wide base• stage 3: wide middle
• stage 4: slender
• stage 5: narrow base
Population Pyramid and Demographic TransitionPopulation Pyramid and Demographic Transition• Stage 2: wide base
• stage 3: wide middle• stage 4: slender
• stage 5: narrow base
Population Pyramid and Demographic TransitionPopulation Pyramid and Demographic Transition• Stage 2: wide base
• stage 3: wide middle
• stage 4: slender• stage 5: narrow base
Population Pyramid and Demographic TransitionPopulation Pyramid and Demographic Transition• Stage 2: wide base
• stage 3: wide middle
• stage 4: slender
• stage 5: narrow base