8.1 Human Population Dynamics

Demography

the study of populations

• age, race, socio-economic status, edu

human patterns

• high growth in LEDCs

  • less access to birth control/less use, more kids to do work, less edu for women

• low growth in MEDCs

  • more edu for women + sex ed, priorities on careers, start fams later

Fertility

ability to have children

• crude birth rate (crude = not age specific)

• total fertility rate

Mortality

number of deaths

• crude death rate

Calculate CBR (crude birth rate)

CBR = # live births/1000 population/year

• typically highest in Africa; lowest in N America, Europe, Aus

(#live births / total population) x 1000 = CBR

TFR

total fertility rate = number of children a woman is expected to have in her life

• critical = 2.2 (to replace a man and a woman)

• means pop will remain stable

• <2.2 = decreasing pop

• >2.2 = increasing pop

patterns follow CBR patterns

Factors that affect birth + fertility rates (MANY RZNS!)

1. Role of children in the labor force or edu

   1. LEDCs = kids work

   2. MEDCs = kids school until 16-18 (then may become economic burden)

2. Rates of Urban living tend to lower fertility rates

   1. more $$, less room

   2. more access to edu

   3. more access to health care + fam planning

3. Women’s status

   1. low status (no say) → inc. in BR bc no edu, homemaker

   2. MEDCs → women can work + control fertility choices

4. Lifestyle choices and cultural norms

   1. MEDCs → later marriages, smaller fams, more stuff than kids

   2. LEDCs → culture may be to hv more kids/marry young

5. Infant mortality rate (IMR) + pensions

   1. IMR = # bbs that die b4 age 1/1000/yr (europe = 3, africa >70)

   2. pensions = retirement fund, no pension → kids need to look after old

6. Family planning + abortion

   1. if available → lower fertility rate

7. Religion and traditions

   1. Catholics → no abortion/birth control (abstinence)

   2. some promote hving many children

8. Government policy

   1. pronatalist: encourages more kids (USA, sweden, china, japan)

   2. anti-natalist: encourages less kids via contraception, fam. planning (FORMER one-child policy china)

Crude Death Rate (CDR)

# deaths/1000/yr

(#deaths in yr / total pop) x 1000

• went down since 1963 because better sanitation (clean water, better nutrition, sewage, diseases, etc.)

Factors that affect mortality (globally)

1. Income

   1. higher income → better food, housing, healthcare, education, electricity/heat, water, clothing

2. Literacy/edu

   1. can care for sick kids (or family)

   2. better access to jobs → (better) health insurance

   3. understand a healthy lifestyle (more likely to lead one)

   4. education of parents influences education of children

3. Food Access → access to (healthy) food can increase longevity

   1. malnutrition = a major cause of death (either lack of. food/low quality food)

   2. MEDCs = diets high in processed or fast food: low nutrient density

   3. LEDCs = poor agricultural technology; insects; poor distribution systems

4. Availability of health care

   1. Most MEDCs: public health care is available

   2. LEDCs: lack of access

5. Water + Sanitation

   1. is water clean and free of pathogens?

   2. how is human waste disposed of? → water treatment, getting rid of trash

6. Access to shelter

   1. protection from the elements (rain, cold, heat, vermin, snow)

Death Rate can vary by age

• older population → higher DR

  • because they are at the end of life

• LEDCs: death is younger

  • more diseases/lack of healthcare

  • less nutrition/food

  • lack of clean water

• MEDCs can have an “unhealthy” lifestyle

  • sedentary lifestyle → lack of movement + poor nutrition leads to several “lifestyle diseases”

  • obesity

  • diabetes

  • heart disease

Rate of Natural Increase (RNI or NIR)

combining fertility + mortality to determine population size

• birth > death → NIR is increasing (pop growth)

• birth < death → NIR decreasing (pop decreasing)

• global NIR = 1.08%

NIR = (CBR - CDR) / 10 (THIS GIVES A PERCENTAGE)

DONT MULTIPLY BY 100 AT THE END

Doubling time (DT)

How long it takes a population to double

DT = 70 / NIR%

• Rule of 70

Population Growth depends on births + deaths

• Early humans: hunter/gatherers; high births + deaths → low pop

• Agriculture: ~12,000 years ago

  • increase in population (b/c more food)

  • new crops from the Americas (potatoes, corn, (choc, sugar), tomatoes, peppers)

• Disease: Black Death, smallpox + other diseases have decimated populations

  • no medicine to cure

• War, famine, diseases are pop controls

  • Thomas Malthus

Causes of decreased death rates

• Agricultural revolution: more food to decrease deaths

• Industrial revolution: people earned wages to buy food, shelter, etc.

• Better sanitation: clean water; didn’t dispose of waste on the streets

• Medicine (vaccines + antibiotics): cured illnesses

  • 1st vaccine (1700s): by Edward Senner for smallpox

  • penicillin: discovered in 1940s

  • 20th Century

• Between 1700-1900 exponential growth began

Future Patterns

How might birth rates change?
Why is the death rate expected to increase?

Thomas Malthus

1700s London

• Essay on the Principle of Population

  • if pop grows unchecked → resources would run out

  • war, famine, disease = population controls

• thought pop. would outgrow food supply

  • war + famine would solve the problem

Support for Malthus

Paul Ehrlich reaffirmed Mathus’ thoughts

Anti-Malthusian theories

Ester Boserup: said advances in ag (green revolution, massive increase in food production) has increased food production to keep up with the growing population

• 1950-84: grain production increased 250%

• famine continues: poor distribution

Evidence to support anti-Mathusian views

• 4 ag revolutions: green, blue (aquaculture), hydroponic (growing crops in water), aquaponic (couple aquaculture with hydroponics)

• med advances hv incr. life expectancy while also improving contraception

  • lower DR and lower BR

• tech advances: solutions to energy issues

• industrial advances to keep pace with demand

• ALL DRIVEN BY FF, esp fertilizers, pesticides, machinery, transportation

Several consequences to continued population growth

• incr. grain prices

• incr. FF prices → incr. in fracking

• Ag land + forests → urban areas

• water withdraw for farming + ppl

• incr. pollution

• topsoil depletion

• overfishing

• food riots (India, 2007)