# Forensic Bones

## Student Laboratory Kit

### Materials Included In Kit

Ruler, transparent, 12", 30
Ulna Bones Chart, 30

Pencil
Tape measure (optional)

### Safety Precautions

This activity is not considered hazardous. Students should follow all normal laboratory safety rules.

### Disposal

All materials can be reused many times.

### Teacher Tips

• Enough materials are provided in this kit for 30 students working individually. All materials are reusable. The activity can be completed in one 50-minute class period.

• Use tape to mark a height line on the wall, with large tape every twelve inches and small tape every inch. Another option would be to create a height line on butcher paper that could be unrolled every year.
• An alternative approach might be for students to collect ulna length data and heights for a large sample of actual people and then create their own predictor graph (probably more accurate). Then students could use this graph to predict the height of individuals A–F.
• Encourage students to investigate further about bone forensics. The internet and other references contain many interesting forensic cases involving bones that students may find very interesting.

### Science & Engineering Practices

Developing and using models

### Disciplinary Core Ideas

MS-LS1.A: Structure and Function
HS-LS1.A: Structure and Function

### Crosscutting Concepts

Systems and system models

### Performance Expectations

HS-LS1-2. Develop and use a model to illustrate the hierarchical organization of interacting systems that provide specific functions within multicellular organisms.

### Sample Data

{10325_Data_Table_1}
{10325_Data_Figure_4}

1. Review the graph. What kind of mathematical relationship seems to exist between the length of the ulna and the height of an individual?

There is a straight line relationship.

1. Convert each person’s height in inches to the more common height in feet and inches. Remember that the whole number is the number of feet but the remainder should be in inches for example 62" = 5.16 which is 5' 2" not 5' 16".

1. Use the ruler to measure the length of your ulna. (It is the longest bone in your forearm. Measure from the end of the bone at your wrist to the end of your elbow bone.) Record the length of your ulna in the space that follows. Then use the graph you constructed earlier to predict your height in cm. Use the tape to measure your actual height if you do not know it.

Ulna length __________ cm
Predicted height __________ cm
Actual height __________cm

Was the graph a good predictor of your height? How might it be made better?

Results will vary naturally since the trend is only a correlation and not an absolute. Larger databases usually provide better predictive curves, but the trend of bone length and height is basically a good overall predictor.

1. Lonesome, Missouri, is a very small town. The police department has three missing persons on record since 1942. Recently, a skeleton was found in an abandoned salvage yard. The skeleton was not intact and many bones had been eaten by rodents. The ulna from a forearm was still intact enough to be measured for length. Police estimate the ulna to be approximately 26.5 cm in length. Which missing person might be the best individual to consider as a match for the skeleton? Justify your choice.

Ray Torres would seem to be the best candidate from the three possible missing persons based upon the earlier prediction graph. Since all individuals were adults at the time they were reported missing, the comparison seems justified.

# Forensic Bones

### Introduction

A dead body has been found and the only things remaining are the bones! What can be learned about the dead person?

• Correlations

• Forensics

### Background

There are more than 200 bones in the human body. For the average male these bones weigh 12 pounds; the average female, 10 pounds. Study of bones can reveal a great deal about a person (dead or alive). Bones may reveal how people lived, how well they ate, whether they had certain diseases, whether they had fractures, whether they were left- or right-handed and maybe even give clues about their occupation. When skeletal remains are found, several important questions must be answered—and often the answers can be determined from just studying the bones:

1. What was the age of the person at the time of death? Bones develop and deteriorate through very predictable stages during an organism’s lifetime. The nature of the jaw bone, for example, might be a clue to the age of the individual (see Figure 1).
{10325_Background_Figure_1_Jaw bones}
1. What was the sex of the person? The clearest indicators are found in the skull and the pelvis area. The average female skull is relatively smaller and lighter and its muscular attachment locations are less prominent. The female forehead is vertically longer, the facial area is rounder, and the jaw mastoid process and supraorbital ridges are smaller (see Figure 2).
{10325_Background_Figure_2_Skull}

The female pelvic cavity is wider in all diameters and is shorter, roomier, and less funnel-shaped than the male pelvis. The female pelvic bones are lighter, thinner and have less obvious muscular attachments.

1. What is the ethnic group of the individual? Experts can characterize skeletons into at least three world ethnic groups based upon a series of key skeletal features.
2. What is the person’s height? Even if a skeleton is not whole, the approximate height can be determined by comparing the length of certain bones with statistical charts that have been developed for that purpose.

In this activity, the height of a person will be predicted using the length of their ulna bone. The ulna bone is the long bone running from the elbow to the wrist on the outside of the arm (see Figure 3).

The formulas for determining the approximate height from the length of the ulna bone are:

Male [3.70 x ulna length (cm)] + 74 cm = height (cm)
Female [4.27 x ulna length (cm)] + 58 cm = height (cm)

{10325_Background_Figure_3_Arm bones}

### Materials

Forensic Bones Worksheet
Ruler, transparent, 12"
Ulna Bones Chart

### Safety Precautions

Although this pencil and paper activity is considered nonhazardous, please follow all normal laboratory safety guidelines.

### Procedure

1. Use the ruler to measure the length of the six ulna bones (A–F) on the Ulna Bones Chart. Record the measurements on the Data Table on the Forensic Bones Worksheet.
2. Calculate each person’s height in cm, for both sexes, and record the results in the Data Table on the Forensic Bones Worksheet.
3. Use the data to construct a graph using the grid provided on the Forensic Bones Worksheet. Graph the length of the male ulna bone versus the height of the individual in cm. Draw a best line fit for the plotted data. Repeat for female ulna bone values.
4. There are 2.54 cm in one inch. Convert the height from cm to inches for each person A–F. Record the results in the Data Table on the Forensic Bones Worksheet.
5. Complete the questions in the Forensic Bones Worksheet.
6. All materials can be reused. Return the Ulna Bones Chart to your instructor.

### Student Worksheet PDF

10325_Student1.pdf

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