Helen Brand
Hunter College High School
71 East 94 Street
New York NY 10128

Forensic science

is the application of science to solve legal issues. It is a wide field, that includes many disciplines. I am a graduate student in the forensic science program at John Jay College and developed a senior elective for my students at Manhattan Center for Science and Math (MCSM) in the 96-97 academic year.

The forensic science elective explored many topics: latent fingerprints, blood groups, blood spatter, DNA, ballistics, microscopy, pathology, among others. The students enjoyed the course and were highly motivated. Guest speakers included detectives from the NYPD ballistics lab and a homicide district attorney from Brooklyn.

This page is for the Anthropology section of the course which took approximately 3 days of 40-minute periods.

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Contents

  • forensic anthropology
  • names of the bones
  • bone sex
  • height
  • calculator
  • faces from skulls

  • Forensic anthropology is the application of the science of physical/biological anthropology to the legal process. The identification of skeletal, and other decomposed human remains is important for both legal and humanitarian reasons. Forensic anthropologists work to suggest the age, sex, ancestry, stature, and unique features of a decedent from the skeleton. (From the American Board of Forensic Anthropologists)

    At MCSM we were fortunate to have 2 skeletons, which the students collected from the prep room and wheeled into the classroom each day. On the first day they made a dramatic entrance and a great motivational begining. The students had previously studied these skeletons in Biology class. They knew of the 206 bones and the functions and importance of the skeleton in human anatomy and physiology.

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    Q.1 What are the names of the bones?

    The Human Skeleton is a nice web site, with diagrams of different bones, but not a detailed diagram of a complete skeleton.

    (from Biology concepts and applications , Third Edition by Cecie Starr, Wadsworth Publishing Company, 1996)

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    Q.2 What sex were our 2 skeletons?

    (from Osteo interactive)

    Sex can be determined in several ways from different parts of a skeleton. The easiest for me is the skull. Males have a sloping forehead while females have a straighter forehead.

    Students then started looking at the skulls of their classmates and were able to see some of these features.

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    Q.3 How can we tell the height of a person from only one bone?

    Students work in pairs, using metric tape measures. Students measure the following in centimeters (cm):

    After the students have collected their measurements they should tabulate them in 2 groups, boys and girls. Human skeletons exhibit sexual dimorphism, and so our mathematical models will be more accurate if used for one sex.

    Ask the students if they see any relationships between the measurements. Are any of the numbers similar? Are all bone measurements proportional to total height? How can we build a model to prove this? Can we use this model to determine height, if only one bone is recovered from a crime scene?

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    Using the TI-82 calculator

    Students can use their TI-82 calculators to find these equations.
    Turn calculator on. Press STAT, then hit ENTER.

    L1 will be the x-axis numbers, the independent variable. Height depends on the length of the femur. L1 will be femur lengths and L2 the total height. Put in data from your class. These sample data are from female adults at Villanova.

    After entering the data, hit STAT PLOT, and hit 1 or ENTER. Plot 1 should be turned On, dots, Xlist:L1, Ylist:L2 . If Plot 1 is Off, put the cursor over On using the arrow keys, and hit enter. Hit ZOOM, scroll down with the arrow key to ZoomStat, and hit ENTER. You will see a scatter plot of your graph on the screen.

    To find the equation for this line, hit STAT, arrow across to CALC, scroll down to LinReg(ax +b) and hit enter twice. It will give you an equation in the form of y=ax+b. Below the equation will be the values for a, b and r. a is the slope of the line, and b is the y-intercept. (r is the correlation coefficient.) In this example, a woman with no femur would have a height of 105.88 cm. This equation is height = 1.23 * femur + 105.88. The correlation coefficient for this line is .65, which is not great. The closer r is to +1 or -1, the better the fit. To draw this line on the graph, hit Y=, then VARS, scroll down to Statistics, hit ENTER, scroll across to EQ, scroll down to RegEQ, and hit ENTER. Hit GRAPH and you will see your scatter plot with the best fit line.

    The accepted line for female height from femur length is: height = 1.95 * femur + 72.85. To comapre this line to the one obtained from our sample, hit Y=, scroll down to Y2=, and put in the equation. Hit GRAPH to see what the 2 lines look like.

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    Q.4 How can we tell what the person looked like?

    Using modeling clay, a skull can be built up to form a life-like reconstruction of a human face. National Geographic shows a picture of such a reconstruction. The Forensic IMAGING Group is developing computers to reconstruct faces from skulls, which could be much faster than artistic illustration and clay sculpture. Faces (a cool web site) does clay facial reconstruction, age progression and other things...

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    Other Links


    Another possbile activity is to disconnect a skeleton and give different parts to different students, and ask them to find the height.

    This page was created by Helen Brand.
    Please contact me by e-mail with comments and suggestions.