Human Populations 02 June 20101Human-Populations.ppt.
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Transcript of Human Populations 02 June 20101Human-Populations.ppt.
Human Populations
02 June 2010 1Human-Populations.ppt
Human populations grow slowly
• K-selected, Equilibrium species– Few large offspring
– Parental care • lasting > 10 yrs.
– Birth interval 2-5 years in most of world.
02 June 2010 Human-Populations.ppt 2
Human population growth
• Historic growth– Exponential growth in recent times.
– Carrying capacity? How much can human populations grow?
02 June 2010 Human-Populations.ppt 3
Human population growth
• Δ N = +B +I –D –E– B = birth rate = live
births/1000 people/year
– D = death rate = deaths/1000/year If B > D, population grows
• For most of human history B = D
02 June 2010 Human-Populations.ppt 4
Human Impact
• IPAT modelI = P x A x T• I = impact
• P = population size
• A = affluence
• T = technology
I = P x A x T x S • S = sensitivity
02 June 2010 Human-Populations.ppt 5
Demography
• Population size
• Population density and distribution
• Age structure
• Sex ratios
02 June 2010 Human-Populations.ppt 6
Demography
• Population density and distribution
02 June 2010 Human-Populations.ppt 7
Demography• Age structure
– Slow growth vs. Rapid growth • Sex ratios
02 June 2010 Human-Populations.ppt 8
Demography• Age structure• Sex ratios
– China’s One-child policy
02 June 2010 Human-Populations.ppt 9
Age structure of USA
• Effect of “baby-boom” generation• Baby-boomers now in
most productive years;• Soon to retire and draw
Social Security;• Soon to suffer medical
needs of older age, need for nursing homes, hospitals, medical doctors;
• Needs MUST be met by smaller population of offspring.
02 June 2010 Human-Populations.ppt 10
Human Population
• I = P x A x T
• Population size
• Affluence
• Technology
02 June 2010 Human-Populations.ppt 11
Human Population
• “Fertility rate”• Average number of
children per female (lifetime)
• Replacement fertility rate
• Δ N = +B +I –D –E
02 June 2010 Human-Populations.ppt 12
Demographic transition
• Demographic transition
02 June 2010 Human-Populations.ppt 13
Demographic transition
• Birth/Fertility rates have changed.
• Fertility: – Total fertility rate• Number of children a woman produces in
childbearing years
– Replacement-level fertility• Number of children necessary to replace parents,
• To maintain constant population size
• ~ 2.1 per woman
02 June 2010 14Human-Populations.ppt
Demographic transition
• Empowerment of women
• Rising standard of living
• Education influences fertility rate
02 June 2010 Human-Populations.ppt 15
Demographic transition
• Empowerment of women
• Family planning• Availability of
contraception
02 June 2010 Human-Populations.ppt 16
Demographic transition
• Factors affecting birth/fertility rates:– Children in labor force, – Urbanization, – Cost of raising & educating, – Opportunities for women, – Age at marriage, – Infant mortality,– Available contraception & abortion, – Religious & cultural values.
02 June 2010 17Human-Populations.ppt
Infant mortality decline
• Improved food supply
• Proper nutrition (vitamins, protein, fats)
• Control of infectious disease.– Influenza
– Diphtheria
– Polio
–Malaria
– & more
02 June 2010 18Human-Populations.ppt
Infant mortality decline
• Infant death for full term babies now rare in USA, N. Europe.
• Contrast to 19th century.– Darwin’s children (born 1840’s)
– Enrico Caruso (1873 – 1923).
02 June 2010 19Human-Populations.ppt
Recently,
• Have death rates changed?
• Life expectancy increased– Increased food supply, better nutrition
– Sanitation/ personal hygiene
–Medical care (immunization, antibiotics)
– Safe water supplies
– Decrease in infant mortality.
02 June 2010 20Human-Populations.ppt
Demography
• Predicting the future of populations:
• Age structure diagrams– People age !
– Fertility rate
– Death rate• (age specific death rates)
02 June 2010 Human-Populations.ppt 21