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Human Populations Studies

or "The Ghost of Populations Past"

Cheryl Callahan, Alan Hoffmann and Sherry Tipps
1991 Woodrow Wilson Biology Institute


PURPOSE:

This ecology activity is a study in population distribution and survivorship curves.

OBJECTIVES:

  1. To accurately collect data regarding age of death of humans from tombstones, newspaper obituary listings, or other resources. (See Teacher Notes)
  2. To analyze data by developing line graphs, bar graphs, and age population pyramids of collected data. A survivorship curve will be generated.
  3. To gain an understanding of age structure of a population and possible effect upon future population size.
  4. To develop an awareness of the effects of age on death rate.

BACKGROUND:

Population studies are an important aspect of the study of ecology. It is important to remember that a population is a collection of individuals of the same species. Populations have their own distinct characteristics apart from any one individual of the population. One of these characteristics is size - how many individuals are in the population. The study of changes in population size involves two primary components: birth rate and death rate. If these two rates remain equal, the population size will generally remain the same. What other factors may affect population size? What will have to happen for a population to increase in age? Decrease?

In this activity the age-related death rate of the human population will be studied. Information about the deaths of humans will be gathered in one of a variety of ways and organized into a life table. An analysis of this information will enable us to understand ages at which the human population is most vulnerable to death. What age groups would you predict to be most vulnerable to death? What factors might contribute to the increased rate of death during those predicted age groups?

MATERIALS:

  • Age-of-Death Resource (See Teacher Notes)
  • 3 x 5 cards
  • graph paper
  • calculator, optional

PROCEDURE:

  1. On 3 x 5 cards, collect the following data from the information source, with one individual on each card: Date of Birth, Date of Death, Age (you can calculate this later), and gender.

  2. Separate cards by:
    A. Gender
    B. Age groups according to Data Table

  3. Count individuals in each group and enter in the Data Table. (These numbers represent "D" in your Life Table.)

Obituary Data

Age Class of MalesDeaths In Age ClassAge Class of
Females
Deaths in Age Class
0-9
0-9
10-19
10-19
20-29
20-29
30-39
30-39
40-49
40-49
50-59
50-59
60-69
60-69
70-79
70-79
80-89
80-89
90-100
90-100

ANALYSIS:

Level I - Complete the Life Tables:

Cemetery Life Table

Age Interval
(X)
# in Study
I
# Who Die in Interval
D
Mortality Rate
M
MaleFemaleMaleFemaleMaleFemale
0-9





10-19





20-29





30-39





40-49





50-59





60-69





70-79





80-89





90-99





100+





  1. For both males and females, determine the number of individuals (D) for each age group from your data tables. Enter the total # of individuals in the study at I for 0-9 years of age. Subtract D0-9 from I 0-9 to determine I for 10-19 years, and so on. (For example, if there was a total of 250 individuals in your study and 7 of them died between the ages of 0-9, 243 individuals would be left in the study for age 10-19.)
  2. Construct a line graph of age group (x) vs. # of individuals left in study (I). This represents your survivorship curve. Plot male and female survivorship curves on the same graph.
  3. Construct a histogram of # of Deaths (D) vs. age group (X). This will give you a rough idea about mortality in each age group.

    Level II -

  4. Determine the % alive in the population for each age group:
    A. Total I for all groups (IT )
    IT = I0-9 + I10-19 + I 20-29 ...
  5. Plot a population age pyramid.

    Level III - NOTE: Omit Step 3, Histogram of (D) vs. (X) from Level I.

  6. Determine mortality rate (M) by dividing # deaths by # individuals in each age group: M = D/I.
  7. Plot a histogram of mortality rate vs. age group.

FURTHER STUDY:

Get data from another century, country or socioeconomic area. Compare the survival curves and account for differences.

QUESTIONS:

  1. What is the dominant age group in terms of numbers in your population study? In terms of mortality: If this is a 20th century population, how does the distribution affect your life?
  2. From your graphs can you tell if the population is stable, expanding, or declining? Explain why this may be so.
  3. What age periods have the highest death rate? Suggest factors that contribute to the higher death rate during those periods.
  4. Compare the survivorship curve of females and males. How do they differ?
  5. How do life insurance companies use such data as we have collected?

NOTES TO THE TEACHER:

(Sample Data and Graphs are Attached)

These data can be collected from many sources. Some are:

  1. family histories (ask each student to research necessary information about grandparents, aunts, uncles, etc.) and pool data for a class project.
  2. church histories or records (these could indicate ethnic groups or socio-economic groups for further studies).
  3. newspaper obituaries over a period of time (weeks, months, years). It is helpful to have at least 100 people of each gender.
  4. microfiche files of obituaries in newspapers, either local or nonlocal (urban vs. rural).
  5. field trips to the cemetery - organize before you go. Chart the area and assign a group to a specific area to reduce duplication. Caretakers are sometimes leery of juveniles in the cemetery, so a call ahead would probably be wise.

These studies can become cross-disciplined with history classes for studies such as effects of wars, plagues, effects of technology, medicine, etc. Information from different centuries can also be examined.

Obituary Data

Age Class of MalesDeaths in Age ClassAge Class of FemalesDeaths in Age Class
0-9330-917
10-191510-1919
20-292420-2932
30-394230-3935
40-494740-4927
50-596650-5960
60-698860-6971
70-7910270-7993
80-895580-8981
90-1001090-1008

Cemetery Life Table

Age Interval
(X)
# in Study
(I)
# Who Die in Interval
(D)
Mortality Rate
(M)
MaleFemaleMaleFemaleMaleFemale
0-94824433317.068.038
10-194494261519.033.045
20-294344072432.055.079
30-394103754235.102.093
40-493683404727.127.079
50-593213136660.205.192
60-692552538871.345.281
70-7916718210293.610.511
80-8965895581.840.910
90-991081081.01.0
100+





   


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