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?


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


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


Demography

• Population size

• Population density and distribution

• Age structure

• Sex ratios


Demography

• Population density and distribution


Demography• Age structure

– Slow growth vs. Rapid growth • Sex ratios


Demography• Age structure• Sex ratios

– China’s One-child policy


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.


Human Population

• I = P x A x T

• Population size

• Affluence

• Technology


Human Population

• “Fertility rate”• Average number of

children per female (lifetime)

• Replacement fertility rate

• Δ N = +B +I –D –E


Demographic transition

• 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



• Empowerment of women

• Rising standard of living

• Education influences fertility rate



• Empowerment of women

• Family planning• Availability of

contraception



• 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.


Infant mortality decline

• Improved food supply

• Proper nutrition (vitamins, protein, fats)

• Control of infectious disease.– Influenza

– Diphtheria

– Polio

–Malaria

– & more


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).


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.


Demography

• Predicting the future of populations:

• Age structure diagrams– People age !

– Fertility rate

– Death rate• (age specific death rates)


Documents

Human Populations 02 June 20101Human-Populations.ppt