1. Is it getting crowded in here?
Population Dynamics

2. Job Available Washing glassware in the Chemistry Lab.
1 hour per day for 30 days.
Pay is either:
A - $10,000/day, or
B - $.01 for the first day, and each subsequent day’s pay is double the previous day.

3. Option A
$10,000 per day for 30 days is a total of $300,000.

4. Option B Day Pay ($) 1 .01 2 .02 3 .04 4 .08 5 .16 Week 1 Pay .31 6
.32 7
.64 8
1.28 9
2.56 10
5.12
Week 2 Pay
9.92
Total
10.23

5. Option B (continued) 11
10.24 12
20.48 13
40.96 14
81.92 15
163.84
Week 3 Pay
317.44
Total
327.67 16
327.68 17
655.36 18
1,310.72 19
2,621.44 20
5,242.88
Week 4 Pay
10,158.08
10,485.75

6. Option B (aren’t we done yet?)21
10,485.76 22
20,971.52 23
41,943.04 24
83,886.08 25
167,772.16
Week 5 Pay
335,058.56
Total
335,544.31 26
335,544.32 27
671,088.64 28
1,342,177.28 29
2,684,354.56 30
5,368,709.12
Week 6 Pay
10,401,873.92
10,737,418.23

7. Why is that so hard to grasp?
We tend to think in linear terms. Work for 8 hours at $10/hr and you will be paid $80.
Linear growth is expressed as a straight line (assuming you have labeled your axes properly).

8. Exponential growth
Exponential growth starts off slowly, but begins to accelerate in amount of growth.
Even if the rate of growth is constant.
Exponential growth is represented by a “J curve”.

9. Why is this important?
The human population eclipsed 7 billion in the recent past.
The rate of growth has not appreciably changed.
The amount of growth is accelerating.
We will need to feed, house, clothe, and care for many more people in the coming years.
The rate of growth is highest in poor countries.

10. World Population Growth

11. World Population Growth
The World’s population reached 1 billion people around
It took 123 more years for that number to reach 2 billion.
The 3 billion mark was hit 33 years later.
It took just 14 years to reach 4 billion.
The 5 billion mark was surpassed in 13 more years.
6 billion was hit 12 years later.
We hit 7 billion 13 years later (2012).
It is estimated that the world’s population grew by 78 million people in 2011.
How many people is that per day, per hour, per minute, per second?
That equals 2.47 people are added to the world’s population.
PER SECOND!

12. World Population Math Expressed as b – d = r
In this equation, r represents the rate of growth.
Demographics in this area are always expressed as #/1000.

13. Area Population Math (b + i) – (d + e) = r
The variables i and e account for movement of people in and out of an area.
Again, the rate of growth is expressed as r.

14. Rule of 72
If r is converted to a percentage, then the doubling time (DT) for a population can be estimated by dividing 72 by r.
Always convert the demographic number to a percent by moving the decimal point one place to the left.
A population will double in 360 years with a rate of growth of 2/1000 (0.2%).

15. Population Density Country Population (2011 est.) Land Area Density
(#/sq. mi.)
Household Size
Household Income
Growth Rate
Bangladesh
151,435,000
56,977
2658
5.3
$1,477
2.13%
Canada
34,615,000
3,849,674 9
2.6
$47,413
0.33%
China
1,339,724,000
3,696,100
362
3.4
$1,876
-0.43%
India
1,210,193,000
1,222,559
990
5.6
$2,307
1.59%
Japan
127,950,000
145,884
877
2.3
$61,120
0.16%
Monaco
35,000
0.75
46,667
2.2
$278,259
0.64%
Russia
142,914,000
6,592,800 22
2.8
$1,820
-0.67%
United States
312,417,001
3,675,031 85
2.5
$67,228
0.6%

16. Replacement Level Fertility
Estimated as 2.1 children per couple in developed nations and 2.5 children in developing nations.
If 10 couples (20 people), in a developed country, have a total of 21 children (2.1 children/couple), this population would stay relatively stable in size.
This number accounts for the number of children who will die prior to reproducing.

17. Total Fertility Rate
Describes the total number of children an average woman in a population is likely to bear during the entirety of her reproductive life.
TFR in developed nations hovers just above 2.0, down from a high of 4.95 (1950).
TFR in developing nations averages 3.8, down from a high of 6.4 (1955).
Worldwide TFR averages 2.6.

18. Carrying Capacity
The carrying capacity of a biological species in an environment is the maximum population size of the species that the environment can sustain indefinitely, given the food, habitat, water, and other necessities available in the environment.

19. Population controls in China
Beginning in 1979, couples were encouraged to pledge to having only one child.
This policy was restricted to urban areas.
Couples who made and kept this pledge received:
Extra food, larger pensions, better housing, free medical care, and salary bonuses.
Their children received:
Free school tuition, preferential treatment in employment
Couples who violated this policy lost any and all privileges.
Recently, China relaxed this policy, as it was so effective, the rate of growth fell below 0 (zero).

20. Age Structure Diagrams
Used to represent age distribution and future trends.

21. Population Trends in Baltimore
Year
Population
Change
1940
859,100
1950
949,708
+ 10.5%
1960
939,024
- 1.1%
1970
905,759
- 3.5%
1980
786,775
- 13.1%
1990
736,014
- 6.5%
2000
651,154
- 11.5%
2010
620,961
- 4.6%

22. Raw Population Size vs. Number of Tax-paying Households
While the population in Baltimore has continued to decline, the number of tax-paying households “bottomed out” in 2003 and has been steadily rising.
Why?
Single adults and couples without children have moved into the city while families have continued to leave.
What do you suppose caused this?
Fear of crime, drugs, and poor schools lead the list of reasons cited.

23. Back to Population
Population density often depends on the dispersion of organisms in a given area.
Dispersion can be:
Uniform, clumped, or random
Additionally, the biotic, or reproductive, potential of a population is the maximum rate at which it could reproduce, assuming unlimited resources.
This is similar to what concept previously discussed regarding niche?

24. Limits to Population Size
Identify the factors which conspire to limit the rate at which a population increases.
What resource presents as the largest Limiting Factor for population?
Water.
When all of the factors that limit a population’s ability to reproduce, that population reaches what we call Carrying Capacity.
Carrying Capacity is the maximum number of organisms which can be sustained over a long period of time, given the available resources.

25. Demographics
Demographics is defined as the “quantifiable statistics of a given population”.
Some of these statistics would be:
Birth rate
Death rate
Gender
Age
Knowledge of language
Education level
Disabilities
Mobility
Home ownership
Employment status

26. Demographic Transition
As time progresses and advances are made available, countries often go through a series of stages that are described as Demographic Transition.
The primary driving force behind this transition is the industrialization of a country.
This occurred in many western nations beginning when?
Beginning in late 19th century.

27. Demographic Transition