Human Populations Ch 9 =4BbkQiQyaYc =4BbkQiQyaYc

 Past 200 years grown exponentially –Expand to new areas –Agriculture –Sanitation, antibiotics, vaccines, fossil fuels  1.23% growth rate (2.4 people every time your heart beats)  Reached 7 billion on October 31, 2011   2050 est. reach 7.2 – 10.6 billion

 Developed countries (MDC) –Highly industrial –High GDP (gross domestic product) – annual market value of all goods/services –Growth 0.1% per year  Developing countries (LDC) –Low to mod. Industrialization –Low to mod. GDP –Growth 1.5% per year –Most Africa, Asia, and Latin America

Factors Affecting Population Size  # births (fertility)  # deaths (mortality)  Migration  Population change = (b+i) – (d+e)  Demographers use: –Birth rate (crude birth rate) - # live births per 1000 people in a particular area –Death rate (crude death rate) - # deaths per 1000 people in a particular area

 China  and India 37%  US 4.5%

 Fertility = # children born to a woman during her lifetime  2 Types of Fertility Rates –1. Replacement level - # children a couple has to replace themselves –2.1 (MDC) and 2.5 (LDC) –Still world pop. would continue to grow for 50 more years (due to future parents)

–2. Total fertility rate (TFR) – ave. # children a woman typically has during her reproductive years –Global 2.7 –MDC now 1.6 –LDC now 2.9 (still above 2.1)

US. Population  million – million  1945 – 1964 baby boom +79 million  1965 – 1977 baby bust –Delayed marriage –Contraception –Abortion  56% growth due to births  44% growth immigration

 Largest ecological footprint  1905 –3 leading causes of death  Pneumonia  TB  Diarrhea –90% US doctors no college edu. –1 in 5 adults illiterate –Daily wage 22 cents per hour –9000 cars on roads –144 mi. paved roads –3 min. phone call from Denver to NY $11 –30 people lived in Las Vegas –Most women washed their hair 1 time per week

Factors Affecting Death Rates  Declining death rates –Increased food supplies –Better nutrition –Advances in medicine –Improved sanitation –Safer water supplies  Has led to: lower premature death rates due to less illness and disease –Rapid growth rate due to low death rate especially in developing countries – –

2 indications of overall health of a country  Life expectancy –1955 – 2006 global (48yrs – 67yrs) 77 in MDC and 65 in LDC  US 47yrs – 78yrs (82 by 2050)  Poorest countries currently 49yrs or less  Infant mortality rate–children who die before age 1 –1965 – 2006 global: MDC 20 – 6.3 LDC 118 – 59 LDC 118 – 59 – 7.6 million die of preventable causes –US 1900 (165) – 2006 (6.7) due to inadequate health care for poor, drug addiction, high birth rate among teens

Factors that affect birth rate  1) importance of children in labor force (LDC)  2) cost of raising children - $250,000  3) availability of pension systems – red. need for support by kids  4) urbanization – better access to family planning  5) edu. and employment opportunities for women –Ex: Brazil literate women 2 children illiterate women 6 children illiterate women 6 children  6) Infant mortality rate

 7) age at marriage ( 25 years or older = fewer kids)  8) availability of legal abortions  9) availability of reliable birth control  10) religious beliefs/traditions/cultural norms

Age structure  = distribution of males and females in each age group in the world’s population  Prereproductive – (0 – 14)  Reproductive – (15 – 44)  Postreproductive – (45 and up)

Pyramids

Demographic transitions  As countries become industrialized tend to go through 4 stages:

 Preindustrial – BR and DR about the same, population stable

 Transitional –BR remains high, death rates drop as living conditions improve  Runaway population growth in this stage

 Industrial- BR and DR about the same, pop growth slows

 Postindustrial- BR drops below death rate, dropping population