Richard R. MacMahon, Ph.D.
Lesson Plans
Introduction
There are a large number of projects that might be attempted by students in order to better understand human evolution and population. I have included two which I think will excite student interest and lead to understanding.
1. Scavenging Bones on the Savanna
We cannot easily get to the savanna of Africa, and yet this is where scientists say we originated. There is a good bit of fossil evidence that indicates that primitive humans were scavengers first and only later became hunters. (Blumenschine and Cavallo, 1992; Katz, 1998). This evidence is primarily the gouges, scrapes and scratches that appear on fossil animal bones found associated with flint tools and other early human remains. Scientists who have studied modern-day bones left by predators and scavengers have been able to observe and categorize the marks left by each type of animal. Each type of scavenger leaves their own particular marks on bones that they have gnawed. Marks left by hyenas, vultures and other animals are all distinctive. Likewise, the marks left by humans using flint knives or stone hammers are also characteristic.
Humans have an incredible urge to consume fats (Eaton and Shostak, 1986). The best source of fat in the lean herbivores of the savanna is the yellow bone marrow. In order to get at this tissue, the bones must be cracked open, either with teeth (as in the case of the hyena and lion) or with a rock ( as has been found in the case of an early hominid). Students may attempt this procedure and get a feel for how easy it really is to get at bone marrow. Bones used for this exercise should not be too large. Veal shanks are about the right size.
2. Population Density and Behavior
Another exercise may show the students how societal behavior is affected by population density. There are many statistical sources for this exercise, both state and national. The hardest part of this exercise may be in finding the statistics needed, which include murder, rape, assault, armed robbery, breaking and entering, drug arrests and teen-aged pregnancies. An almanac is probably the best place to start. This exercise will also give the students practice in extracting raw data, manipulating the data and graphing the results. The results may show a correlation between population density and societal behavior. The results may not always be conclusive, it depends in part upon the populations selected.
The following exercises are to be xeroxed and passed out to the students.
Scavenging Bones on the Savanna
We cannot easily get to the savanna of Africa, and yet this is where scientists say we originated. There is a good bit of fossil evidence that indicates that primitive humans were scavengers first and only later became hunters. (Blumenschine and Cavallo, 1992; Katz, 1998). This evidence is primarily the gouges, scrapes and scratches that appear on fossil animal bones found associated with flint tools and other early human remains. Scientists who have studied modern-day bones left by predators and scavengers have been able to observe and categorize the marks left by each type of animal. Each type of scavenger leaves their own particular marks on bones that they have gnawed. Marks left by hyenas, vultures and other animals are all distinctive. Likewise, the marks left by humans using flint knives or stone hammers are also characteristic.
1. Students should work in pairs. Your first assignment for this exercise is to find and bring to class two stones. One of these stones should be about fist size, and should fit comfortably in your hand. You will use this stone as a hammer, so make sure it is large enough to extend beyond your fingers. The second stone should be somewhat larger, and will be used for an anvil. A somewhat flat top and bottom will make a more stable and efficient base. Make sure the stones you select are hard and solid. They should not disintegrate or chip excessively when struck together.
2. The next period, your teacher will pass out to each pair of students a bone with some meat on it. Using a scalpel, cut off as much meat as you can and weigh it. Then examine the bone under a stereomicroscope (or with a magnifying glass) for marks that you made in removing the meat. Sketch the bone and marks. Are there any other marks present? Where might these marks have come from? If some students have dogs, try taking the bone home and letting your dog play with it for a few hours. Again, examine the bone under a stereoscope. Did the dog leave any marks on the bone? Where these marks different from the marks that you left? Sketch the bone and marks.
3. Review the structure of a bone in your biology text. Where in the bone is the fatty marrow? Finally, place the bone on your anvil stone (on the floor, under some newspaper) and strike it with the hammer stone. Be careful! Mashed finger tips are very painful! Wear protective lab eye ware when doing this part of the exercise. A stone or bone chip in the eye is not much fun! Crack the bone open, twist the two parts of the bone and remove the fatty marrow from the center of the bone. Weigh the marrow. The calories found in fatty tissue such as the marrow = 9.2 C/gram, while the calories found in muscle = 5.1 C/gram. Was it worth it to crack the bone open and extract the marrow? How many calories did you get from the marrow tissue? How many from the muscle?
4. Dispose of all materials properly in the wastebasket or where directed.
Population density and behavior
This exercise may show you how societal behavior is affected by population density. There are many statistical sources for this exercise, both state and national. This exercise will give you practice in extracting raw data, manipulating the data and graphing the results. The results may show a correlation between population density and societal behavior. The results may not always be conclusive, it depends in part upon the populations selected and the accuracy of your work.
1. Obtain from the teacher an almanac or handout that shows population figures for cities and towns in your state. Select four cities and towns of different sizes and socio-economic conditions. Enter the population values in the table below.
TABLE I. Population Values for Four Cities and Towns
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City/Town
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Population
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Area
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Density
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2. Plot on a graph the values for population density (x axis) versus the number of murders per thousand people in one year (y axis). Is there a correlation between population density and violence? Plot separately population density against the number per thousand of rapes, assaults, armed robberies, breaking and enterings, drug arrests, teen-aged pregnancies and other statistics available. Using different symbols, you should be able to plot all of your data on one graph. The resulting graph is called a scattergram. This scattergram should show a correlation between population density and some societal behavior.
3. What is your conclusion? Is there any correlation between population density and behavior? Do you think we are more stressed and under greater pressure when we live closer to one another? For homework, write an essay on our human living arrangements. What could we do to alleviate stress in the population? Can most crimes be reduced by living further apart? What are your ideas?