anth 225 lab5 lotus 123

Anth 203 Human Ecology Lab 2

Using a Spreadsheet to Study Population Ecology and Climate

In this lab you will use a spreadsheet (Microsoft Excel) to help model some aspects of population growth.

GETTING STARTED

1. Turn computer on (if it isn’t already).

2. Shift to the PC side [apple key + m]

3. Run Excel - double click on the Excel icon

You should now see the spreadsheet with the rows indicated by numbers and the columns indicated by letters. The size of the spreadsheet is limited only by the computer’s memory capacity and hard disk space. At the bottom of the sheet there are a series of numbered tabs which can take you other sheets. All the sheets together consitute a workbook which is saved as a file. Each cell of the spreadsheet is designated by its column letter and row number, e.g. A1, C19, Z180 etc. You can move to a particular cell by using the arrow keys, tab keys,page keys, the sidebars, etc.

I. Demonstration - Convert Farenheit to Centigrade

1. Move to cell B2 (Use Arrow keys)

2. Type Degrees F (enter)

3. Move to D2

4. Type Degrees C (enter)

5. Move to B3

6. Type 1 (enter)

7. Move to B4

8. Type =B3+1 (enter)

[this adds 1 to the contents of B3 and places the result in B4]

9. Using the mouse, click on B4 and then click and hold the lower right hand corner of B4 and drag it down to B27. Did you end up with a column of

numbers 1 - 25?

10. [Remember the Formula C = 5/9(F-32)]

11. In cell D3 type =5/9*(B3-32) (enter)

12. Click on D3 and drag the lower right corner down to D27

13. Use the PgDn [pagedown] key to see what happened

14. To make things look better reduce the number of decimal places shown for the Centigrade column. Highlight the column and click on the decimal reduction

toolbar icon til you get 1 decimal point remaining

15. Move to B3 and type 100 (enter) What happens?? Neat, huh!?

You have felt the power of spreadsheet formulas, relative addressing, and autofills!!! Think of all the nifty tables you can create!!!

Part II.: Do Sections A and B (Have a look at C if you like!)

A. Microsoft meets Malthus

Click on the sheet 2 tab at the bottom of the spread sheet
In A2 type Resources and in B2 type Population
In A3 type 1000 and in A4 type =A3+100
Click on A4 and drag the corner down to A18; (the value of A18 should be 2500)
In B3 type 10 and in B4 type =B3*1.5
Click on B4 and drag down to B18; (the value should be 4378.939)

Congratulations! You have created an arithmetic and an exponential growth series

Now to graph the two:

On the tool bar click on the graph wizard icon; the cursor will turn to a miniature bar graph
Click on the graph just to the right of your data columns - somewhere around F15
As soon as you click, the Chart Wizard dialog box, step 1, appears. At this point you can highlight cells A2:B18 or type =A2:B18 into the dialog box; then click on Next
From the chart type selection click on Line and on the Line selection menu click on type number 2
You should see a chart; all you have to do now is click on finish and a chart will be embedded in your sheet. You can drag it around and enlarge it by pulling with the mouse on one of the corner handles. You can also go back to your number columns and change the formulas or values. Exponential growth can take many forms.

Print out your graph and turn it in with the excercises below A. Compound Interest Formula Using the compound interest formula to calculate population growth over a specified period of time. Put the following formula into your spreadsheet: P₂ = P₁* (1 + r)^t

P₁= initial population

P₂= population at end of period

r = annual rate of growth (in percent, e.g 2% = .02)

t = years of population growth.

spread sheet hint: use "^" to raise the expression (1 + r) to a specified t

Using the formula answer the following:

1.If a band of 100 paleoindians entered the Americas 14,000 years ago and grew at a steady rate of 1%, how large would the population be by 12,500 years bp?

2.What would be the approximate average annual rate of growth for the world population to reach 9 billion in 2050 (assuming an initial population of 6 billion in 2000)?

3. If the rate of population growth remained constant at 2% from 2000 to 2050, what would the population in 2050 be (assuming the population in 2000 is 6 billion)

B. Climate (Temperature and Precipitation)

In the Pub Data folder under Anth 203 you will find a folder labled "PHL and LAX." This folder contains 4 Excel files
for Philadelphia and Los Angeles temperature and precipitation. Each file has a record of approximately 40 years of monthly
mean temperatures or precipitation.

1. Compute the Average (mean) for monthly temperature or monthly precipitation for all months for the four files
Q. Which monthly series shows the greatest variation? Which shows the least variation?

2. Make a bar chart of mean monthly precipitation for Los Angeles and a line graph for mean monthly temperature
for Philadelphia. Print them out.

    3. Make a comparative bar chart of total annual precipitation for Philadelphia and Los Angeles over the 40 year
            period. Briefly describe the patterns you see. Is there any correlation between the two cities precipitation over
            this period of time?

    4. Extra Credit. Construct a climograph for Los Angeles. A climograph shows the pattern of temperature and precipitation
            over the year. Temperature is on the y (vertical)axis and precip on the x (horizontal) axis. You will need to cut and
            paste the mean monthly temps from one excel file and paste them next to the mean monthly precip in the other LAX file.
            Use a scatter plot to plot the points. Can you connect the dots and label the months?

For reference Only!!!
C. Logistic Growth

Exponential growth can be transformed to logistic growth if the rate of growth can be gradually slowed down. What makes the growth slow down is a big topic for investigation, but we can investigate what the consequences are using a spread sheet.

Assume that there is a fixed carrying capacity to the area under study. Call this quantity "K" (This is a Malthusian assumption)

Assume further that as population, "p," grows, the rate of growth, "r," will decrease as the population approaches K. (Somehow the population senses diminishing resources and reproduces at a slower and slower rate).

One way to make r shrink as p approaches k is by the formula:

r₂= r₁* (K – P)/K

Using initial values of

P = 10

K = 2000

r = 0.2

Construct a table in Excel which spans 40 time intervals and make a graph of your result as a separate sheet. Print out the graph and send me (rdavis@brynmawr.edu) the spreadsheet as an attachment

Extra credit

What if Malthus is wrong and George Bush is right? The latter, George W.’s father, said "every human being represents hands to work, and not just another mouth to feed." K can grow! Roll over Malthus, and roll up your sleeves! Get to work! Can you model a growing K without P going infinite?

p.s.

Here are a couple of excellent web sites where you can find out more about human population patterns

The Bureau of the Census has a huge amount of information. Here is a page on world population patterns:

www.census.gov/ipc/www/world.html

Trinity college has the following site which has good content and excellent links: