L11 Human Population Growth

Question 1

What is the human population growth equation?

Answer 1

dN/dt = rN

Nt = Noexp(rt)

r assumed constant
can be expressed as a percentage
r = 100(ln(Nt/No)/t)

Question 2

What is doubling time

Answer 2

Doubling time (td) = the length of time required to double to population

N = 2No
2No = Noexp(rtd)

td = constant for exp growth

2 = exp(rtd)

td = ln(2)/r

r NOT IN PERCENTAGE FORM

Question 3

What is r’?

Answer 3

r = change in specific rate of pop growth

b’ = specific birth rate (births/1000/yr)
d’ = specific death rate (deaths/1000/yr)

r’ = b’ - d’

Question 4

Why have birth and death rates changed?

Answer 4

1) better medical practices = decreased dN

2) birth and fertility rates declined = decreased bN

3) higher Human Development Index (HDI) = lower birth rates
- Eduacation + Life Expectancy + Income = HDI

Question 5

Why have death rates declined?

Answer 5

1) Better Medical Practices
- vaccines
- handwashing
- sterile surgeries
- maternal health
- antibiotics
- advanced cancer treatment etc…

2) Better nutrition
- production, storage, preservation and distribution

3) Agricultural Revolution(s)
-plants and animals domesticated less independently = hunter-gather societies tun to settles, hierarchical ones

4) Green Revolution
- after WWII, many biotechnology improvements increased agricultural yields = millions of ppl saved from starvation (long term effects still controversial tho)
–> modern management techniques
–> irrigation
–> fertilizers and pesticides

5) Improved Water Quality
- wastewater and water treatment
- segregation of wastewater from drinking water sources