INTRODUCTION

The analytical stage of forensic anthropology involves answering questions that lead to identification of the individual whose remains are being examined.  The questions asked in developing a biological or demographic profile for an individual include the following:

• What is the race of the individual?
• What is the sex of the individual?
• What is the age of the individual?
• What is the stature of the individual?
• What pathologies did the individual have?
• What traumas did the individual have?
• What idiosyncratic traits did the individual have?

 OBJECTIVES

• To learn how to use anthropometric measuring instruments.

• To recognize and assess skeletal indicators of race.

• To practice carefully handling skeletal material.

READINGS

• Review the lecture notes and handouts on race determination.

• Review Chapter 7 of the Byers text and Byers lab manual. 

TERMS

• biological (demographic) profile
• osteometry
• anthroposcopy
• metric trait
• nonmetric trait
• sliding caliper
• spreading caliper
• osteometric board
• dorsal/anterior
• ventral/posterior
• proximal
• distal
• superior
• inferior
• race
• ancestry
• Mongoloid
• Negroid
• Caucasoid

USING OSTEOMETRIC MEASURING DEVICES

You will be using several osteometric measuring devices to complete this lab.  Carefully follow the directions for using these devices to insure that instruments and bones are not damaged. Osteometric equipment is expensive because of the precision with which they are manufactured; special care in using the equipment must be exercised at all times.  All measurements must be made in metric units.  Ask for help reading the instruments, if needed.

Sliding Caliper

The sliding caliper is used to make linear measurements on bones.  We are using manual calipers and digital sliding calipers that run on batteries.  Each student should practice using both types of calipers.  The level of accuracy is 0.1 mm for the manual and digital calipers.

       MANUAL SLIDING CALIPER

1. Depress and hold the release button on the bottom part of the caliper.
2. Slide the right half of the caliper to the right to open it up.  Open it beyond the size of the bone being measured.
3. Place the bone between the two lower pinchers.
4. Gently slide the right half of the caliper back to the left to close the lower pinchers against the edges of the bone.  Be very careful!
5. Read the measurement from the top line of measures.  (Metric along the top, English along the bottom.)  The numbers correspond to centimeters.  The tick lines between the numbers correspond to millimeters.  Select the closest millimeter reading without going over.  The small scale is for tenths of a millimeter; find the number along this scale that best lines up with a number of the main centimeters scale.  Your answer should read, for example, 2.35 cm.
6. Depress and hold the release button and slide the right half of the caliper to the right again to open it up.
7. Remove the bone from the caliper.
8. Close the caliper.
9. Multiply your answer by 10 to convert to millimeters.  In our example, your final answer would be 23.5 mm.
10. Record your measurement in millimeters.
11. Repeat these steps for the next measurement.

        DIGITAL SLIDING CALIPER

1. Close the caliper completely.
2. Press the ON/ZERO button to turn on the caliper.
3. Make sure the caliper is set on metric (millimeters) instead of English (inches). Press the MM/IN button to change from English to metric if needed.
4. Press the ON/ZERO again to reset the caliper to zero.
5. Slide the right half of the caliper to the right to open it up.  Open it beyond the size of the bone being measured.
6. Gently slide the right half of the caliper back to the left to close it against the edge of the bone. Be very careful!
7. Read the measurement, which is expressed as 000.0 mm.
8. Slide the right half of the caliper to the right again to open it up.
9. Remove the bone from the caliper.
10. Close the caliper.
11. Record your measurement in millimeters.
12. Repeat steps 4-11 for the next measurement.
13. Press the OFF button when you are done measuring.

The spreading caliper is used to make linear measurements around the protrusions on the skull. The level of accuracy is 1 mm but you can estimate to 0.1 mm.

1. Rest the skull on a cushioned surface, or have your lab partner hold the skull securely.
2. Place one end of the spreading caliper on the first bone landmark, supporting the end of the caliper with your finger if needed.
3. Spread open the other end of the spreading caliper.
4. Place the other end of the spreading caliper on the second bone landmark, supporting the end of the caliper with your finger if needed.
5. Read the measurement.  The numbers on the scale are centimeters, and the tick lines between the numbers are millimeters.  You'll have to estimate the measurement of tenths of a millimeter.  For example, 35.73 cm might be the reading.
6. Open the spreading caliper away from the bone landmarks.
7. Remove the spreading caliper.
8. Close the spreading caliper.
9. Multiply your answer by 10 to convert to millimeters.  In our example, your final answer would be 357.3 mm.
10. Record your measurement in millimeters.
11. Repeat the steps for the next measurement.

GENERAL INSTRUCTIONS

Carefully handle the instructional casts and bones laid out in the lab, being sure to keep the bones with their labels.  Some of the ends of the bones where you will be making measurements are very delicate and will degrade if handled improperly.  Keep the materials on the bubble wrap to cushion them from the hard table surfaces, and wear gloves when working with real bones.

Record your responses to the questions in pencil on the answer sheet provided in the lab.  

Work as a small group with the skulls, since we have a limited number of skulls.  Each group will be given a time limit with each skull specimen.

When working in a group, it is essential that all group members look at the bones and make the measurements.

Use reference books in the lab as needed.  Ask the instructor or assistant if you don't understand something.

The lab is due on Thursday, March 27 at the beginning of class. Late labs will not be accepted.
 

RACE DETERMINATION

Patterns of geographic variation of the human skeleton are used to identify the race or ancestry of an individual.  Most forensic anthropologists use a three-race model that includes Mongoloid, Negroid, and Caucasoid races.  Native Americans are typically included in the Mongoloid race.

Compared to sex, age, and stature estimation, race determination is "more difficult, less precise, and less reliable" because "no human skeletal markers ... correspond perfectly to geographic origin" (White 1991:328-329).  In addition, many skeletal indicators used to estimate race are nonmetric traits, whose documentation through anthroposcopic methods can be somewhat subjective, varying for researcher to researcher.  However, race estimation is a critical endeavor in forensic identification as sex, age, and stature estimation are greatly influenced the race of the individual.

Skeletal indicators of race focus primarily on skull and dental traits.  Racial indicators on the skull are both nonmetric and metric traits and include robusticity, lengths and widths of skull features, shapes of skull features, and unique population-specific dental features.

The Giles-Elliott method is a quantitative means of estimating race based on the skull, but we will not be using this approach for our lab assignment; this method will be demonstrated if you undertake research with the instructor at a future date.  Postcranial skeletal elements used in race estimation include the femur, tibia, coxa, scapula, rib, and calcaneus.  In this lab, however, we will be examining only skull racial indicators.

The following drawings illustrate some of the skull differences among the three major human races.

  Caucasoid skull drawings (left from Bass 1986:84, right from France 2003:239).

  Negroid skull drawings (left from Bass 1986:85, right from France 2003:238).

  Mongoloid skull drawings (left from Bass 1986:86, right from France 2003:240).

The following table summarizes typical expressions of 28 metric and nonmetric skull traits for the three human races.  A guide to assessing these traits follows the table.
 
 

TRAIT	CAUCASOID	NEGROID	MONGOLOID
1. cranial index	75 to 80, mesocranic	less than 75, dolicocranic	greater than 80, brachycranic
2. sagittal contour	arched	flat with bregmatic or post-bregmatic depression	arched
3. keeling of skull vault	absent	absent	present
4. total facial index	greater than 90, narrow to very narrow	less than 85, broad to very broad	85 to 90, medium or average
5. facial profile	orthognathic (straight, flat)	prognathic (projecting), especially in the alveolar area	intermediate to mostly orthognathic
6. nuchal ridge profile	pinched and prominent	slightly pinched	rounded
7. base chord	long	long	short
8. suture pattern	simple	simple	complex
9. metopic suture	present	absent	absent
10. wormian bones	absent	absent	present
11. eye orbit shape	angular and sloping	square or rectangle	rounded and non-sloping
12. lower eye border	receding	receding	projecting
13. nasal index	less than 48, leptorrhinic (narrow)	greater than 53, platyrrhinic (wide)	48 to 53, mesorrhinic (intermediate)
14. nasal cavity shape	tear shaped	rounded and wide	oval shaped
15. nasal bones	"tower shaped," narrow and parallel from anterior, slightly arched in profile	"Quonset hut shaped,"           wide and expanding from anterior, no arch in profile	"tented," narrow and expanding from anterior, arched in profile
16. nasal overgrowth	absent	absent	present
17. nasal sill or dam	present	absent	absent
18. lower nasal spine	large and sharp	small	small
19. zygomatic arches	narrow and retreating	medium to large and retreating	projecting
20. external auditory meati	round	round	oval
21. palate shape	triangular	rectangular	parabolic or horseshoe shaped
22. palate suture	irregular	irregular	straight
23. occlusion	slight overbite	slight overbite	edge-to-edge or even
24. central incisors	blade shaped	blade shaped	shovel shaped
25. shape of ascending ramus of mandible	pinched at midsection	back slanted	wide and vertical
26. projection of ascending ramus of mandible	non-projecting	projecting	non-projecting
27. gonial angle	slightly flared	not flared	slightly flared
28. chin profile	prominent and projecting	rounded	slightly projecting

1.  CRANIAL INDEX:  Use the spreading caliper.  Measure the maximum breadth of the skull from euryon (eu) to euyron (eu).  Measure the length of the skull from glabella (g) to opisthocranion (op).  Divide the cranial breadth by the cranial length and multiply by 100.   (See figures below for landmarks.)

2.  SAGITTAL CONTOUR:  Holding the skull in profile, examine the contour of the cranium along the sagittal suture.

3.  KEELING OF SKULL VAULT:  Holding the skull in anterior position, examine the contour of the cranium.  Keeling is a pinched appearance along the sagittal suture.

4.  TOTAL FACIAL INDEX:  Use the sliding caliper to measure the maximum heighth of the face from nasion (n) to gnathion (gn).  Use the spreading caliper to measure the maximum width of the face from zygion to zygion (zy).  Divide the facial height by the facial width and multiply by 100.  (See figures below for landmarks.)

5.  FACIAL PROFILE:  Holding the skull in profile, gently "place one end of your pencil on or near the anterior nasal spine (on the midline of the skull) at the base of the nasal aperture [nasal cavity].  Lower the pencil toward the face so that the pencil will touch the chin" (Bass 1987:87).  If the pencil hits the alveolar area of the mouth, the face is prognathic.  If the pencil extends to the chin, the face is orthognathic.  "Caucasoids have a 'flat' (orthognathous) face in the dental area along the midline.  This is the opposite of the Negroid face, which exhibits protrusion of the mouth region, known as prognathism.  ... Negroids are noted for alveolar prognathism, or an anterior protrusion, of the mouth region.  A pencil or ballpoint pen placed with one end on the nasal spine (midline at base of nasal aperture) will not touch the chin (the teeth protrude too far forward)" (Bass 1986:87).

6.  NUCHAL RIDGE PROFILE:  Holding the skull in profile, examine the nuchal ridge and note the shape.

7.  BASE CHORD:  Holding the skull in inferior view, examine the distance between opisthion and opisthocranion. Measure the distance using the linear caliper.

8.  SUTURE PATTERN:  Examine the pattern of the cranial sutures (sagittal, cornonal, squamosal, lambdoidal) and describe the pattern as simple (not very convoluted) or complex (very convoluted).

9.  METOPIC SUTURE:  Examine the frontal bone superior to the nasal bones for evidence of a short suture known as the metopic suture.

10.  WORMIAN BONES:  Examine the lambdoidal suture and look for small bones within the suture line.  These bones are called wormian bones.

11.  EYE ORBIT SHAPE:  Examine BOTH of the eye orbits from the anterior view.  Describe the overall shape as rounded or squared.  If the eye orbits are rounded, examine the top border to see if it is level or if it slopes laterally.

12.  LOWER EYE BORDER.  Examine the skull in profile, gently placing a pencil vertically across the eye orbit.  If the pencil is a vertical plane, then the lower eye border is projecting.  If the pencil is not a vertical plane, then the lower eye border is not projecting.

13.  NASAL INDEX:  Using the sliding caliper, measure the maximum breadth of the nasal cavity (at right angles to the nasal height), from alare to alare (al).  Measure the nasal height from nasion (n) to nasospinale (ns).  Divide the nasal breadth by the nasal height and multiply by 100.  (See figures below for landmarks and measurement information.)

14.  NASAL CAVITY SHAPE:  Examine the overall shape of the nasal cavity from the anterior view.

15.  NASAL BONES:  Examine the shape of the nasal bones from the anterior and lateral views.  From the anterior view, check the width of the bones and whether or not they expand outward from superior to inferior.  For the lateral view, check if the bones arch downward (concave up).

16.  NASAL OVERGROWTH:  Examine the nasal bones from BOTH lateral views.  An overgrowth is present if the inferior ends of the nasal bones overhang the superior edge of the nasal cavity.

17.  NASAL SILL OR NASAL DAM:  "Carefully observe the base of the nasal aperture [nasal cavity or opening]. With your pencil or ballpoint pen resting against the bone of the maxilla just below the nasal opening, try to run the pencil or pen gently into the nasal opening.  In Caucasoids there is usually a dam (nasal sill) that will stop the pen or pencil.  In Negroid skulls there is no dam or nasal sill, and the pen easily will glide into the nasal aperture.  Mongoloid skulls will range between these two extremes" (Bass 1986:83).  Be extremely careful when inserting a pen or pencil into the nasal cavity to avoid bone damage. Be sure to check BOTH sides of the nasal cavity.

18.  LOWER NASAL SPINE:  Holding the skull in lateral view, examine the lower nasal spine that extends from the inferior edge of the nasal cavity.  Describe the shape.

19.  ZYGOMATIC ARCHES:  "Hold the skull with the occipital region in your hand and the facial area up.  Place a pencil across the nasal aperture [nasal cavity].  Now try to insert your index finger between the cheek (zygomatic) bones and the pencil.  Caucasoids have a face that comes to a point along the midline and cheek bones that do not extend forward.  This will allow you to insert your finger between the cheek bones and the pencil without knocking the pencil off.  Mongoloids have a much flatter face (the cheek bones extending much further forward), and it is difficult to insert your finger between the pencil and the cheek bones on a Mongoloid skull without knocking the pencil off" (Bass 1986:83). Be sure to check BOTH zygomatic arches.

20.  EXTERNAL AUDITORY MEATI:  Holding the skull in lateral views, examine the overall shapes of the external auditory meati. Be sure to check BOTH external auditory meati.

21.  PALATE SHAPE:  Holding the skull in inferior view, examine the palate area, which includes the maxillae and palatines.  Describe the overall shape.

22.  PALATE SUTURE:  Holding the skull in inferior view, examine the middle portion of the suture between the maxillae and palatines.  Describe the shape.

23.  OCCLUSION:  Holding the skull in lateral view, examine the occlusion of the upper and lower incisors.  If the maxillary incisors are anterior relative to the mandibular incisors, this is an overbite.  If the maxillary and mandibular incisors meet evenly, this is edge-to-edge occlusion.

24.  CENTRAL INCISORS:  Holding the mandible in superior view and/or the maxillae in inferior view, examine the shape of the central incisors.  Shovel-shaped incisors have posterior-oriented projections.

25.  SHAPE OF ASCENDING RAMUS OF MANDIBLE:  Holding the mandible in lateral view, examine the overall shape of the ascending ramus. Be sure to check BOTH lateral views.

26.  PROJECTION OF ASCENDING RAMUS OF MANDIBLE:  Holding the mandible in posterior view, examine the posterior edge of the ascending ramus. If the bone projects toward the midline, the ascending ramus is projecting. If the bone does not project toward the midline, the ascending ramus is non-projecting.

27.  GONIAL ANGLE:  Holding the mandible in anterior view, examine BOTH of the gonial angles to see if they are rounded or outward flaring.

28.  CHIN:  Holding the mandible in lateral view, examine the relative projection of the chin.
 

The metric measurements are based on skull landmarks that are illustrated in the following drawings of the anterior, inferior, and lateral views of the skull (Bass 1987:63-65).  The skull landmarks you need to know and use for this lab are:  glabella (g), opisthocranion (op), opisthion (o), euryon (eu), nasion (n), nasospinale (ns), alare (al), gnathion (gn), and zygion (zy).
 

Assignment

Examine the four skulls labeled SKULL1, SKULL2, SKULL3, and SKULL4.  Compare them to the known skulls and figures in the reference materials. 

On the answer sheet, circle all the skull characteristics that you observe, noting that a trait may be present on one side of the skull but not the other (in other words, check both sides!).

For the indices, you will also record the quantitative value (rounded to tenths place) in the first column of the answer sheets.

If a bone is missing or broken such that the trait cannot be evaluated on either side of the skull, mark the last column of the answer sheet for that particular trait.

Using the three-race model, determine the most likely racial affiliation for each specimen. If appropriate, use qualifying terms such as "probably" or "possibly" if a specimen has a significant number of traits of more than one race, but select the race with the largest number of traits.
 

REFERENCES

Bass, W. M. (1987) Human Osteology: A Laboratory and Field Manual (3rd ed.). Missouri Archaeological Society, Columbia.

France, D. L.  (2003) Lab Manual and Workbook for Physical Anthropology (5th ed.). West / Wadsworth, Belmont, CA.

White, T. D. (1991) Human Osteology. Academic Press, San Diego.