3. S-Shaped Curve – population initially
shows exponential growth, then
Population Growth
the population numbers level
out as it approaches K
Carrying Capacity (K) –
The largest population a
particular environment can
support sustainable (long-
term) assuming there are no
changes in that environment.

4. Exponential Population Growth
The larger the population gets the faster
it grows.
Population of bacteria = 2n
n = the number of times the bacteria have
doubled in size, occurs every 30 minutes
In 24 hours the bacteria would double 48
times (n = 48)
Therefore, the population of bacteria after
24 hours of growth is:
248 = 281,474,976,710,656

20. How Populations are Measured
3. Doubling Times: number of years it will take a population to double,
assuming the current growth rates remain constant
Rule of 70: a means of calculating doubling times, 70 divided by the
current annual growth rate.
population doubling time = 70 ÷ annual rate of growth
This rule applies to things at exponential growth (e.g., human
population growth)
In finance we have the rule of 72 that says: If I invest $100 at 9% interest per
year then I can divide 72 by 9 (72/9 = 8), and this will tell me that in 8 years I will
have $200.

21. At 1.3% population growth, human
population will double in 55 years!

25. NOVA – Pregnancy Obstetric Fistula and Child Birth
in Ethiopia (Chapter 4, beginning of 5, 6)
“A Walk to Beautiful”
http://www.pbs.org/video/video/980049841/chapter/1/search/Africa
%20Poverty
Over 9,000 woman and girls develop fistula each
year in Ethiopia alone

27. NOVA – Child Birth in Developed
versus Undeveloped Country:
http://www.pbs.org/wgbh/nova/
beautiful/women.html

38. “Vampires” among the plague victims excavated in
Italian Plague (The Black Death) Graves from 1300s
– March, 2009.
http://news.nationalgeographic.com/news/2007/08/
photogalleries/massgrave-pictures/photo4.html

46. Meadows, Dennis et al., The Limits to Growth, Potomac Associates, Washington DC,
1972; Meadows, Donella et al., Beyond the Limits, Earthscan Publications, 1992.