Upload
zubi-haq
View
216
Download
0
Embed Size (px)
Citation preview
7/30/2019 Western Kentucky University
1/20
WESTERN KENTUCKY UNIVERSITY
Anth 300 Forensic Anthropology
Dr. Darlene Applegate
Spring 2008Lab 9: Race Determination
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?
In this lab, we will examine the first of these questions: race determination.
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
7/30/2019 Western Kentucky University
2/20
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 thatinstruments 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.
7/30/2019 Western Kentucky University
3/20
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.
Spreading Caliper
7/30/2019 Western Kentucky University
4/20
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 pencilon 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 allgroup members look at the
bones and make the measurements.
7/30/2019 Western Kentucky University
5/20
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, andunique 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 threemajor human races.
7/30/2019 Western Kentucky University
6/20
7/30/2019 Western Kentucky University
7/20
Caucasoid skull drawings (left from Bass 1986:84, right from France
2003:239).
7/30/2019 Western Kentucky University
8/20
7/30/2019 Western Kentucky University
9/20
Negroid skull drawings (left from Bass 1986:85, right from France
2003:238).
7/30/2019 Western Kentucky University
10/20
7/30/2019 Western Kentucky University
11/20
Mongoloid skull drawings (left from Bass 1986:86, right from Franc
e 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, mesocranicless than 75,
dolicocranic
greater than 80,
brachycranic
2. sagittal
contourarched
flat with bregmatic orpost-bregmatic
depression
arched
3. keeling of
skull vaultabsent 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 profileorthognathic (straight,
flat)
prognathic (projecting),
especially in the
alveolar area
intermediate to mostly
orthognathic
6. nuchal ridgeprofile
pinched and prominent slightly pinched rounded
7. base chord long long short
8. suture pattern simple simple complex
9. metopic
suturepresent absent absent
10. wormianbones
absent absent present
11. eye orbit
shapeangular and sloping square or rectangle
rounded and non-
sloping
12. lower eye
border
receding receding projecting
13. nasal indexless than 48,leptorrhinic (narrow)
greater than 53,platyrrhinic (wide)
48 to 53, mesorrhinic(intermediate)
14. nasal cavity
shapetear shaped rounded and wide oval shaped
15. nasal bones "tower shaped," narrow
and parallel from
"Quonset hut
shaped," wide and
"tented," narrow and
expanding from
7/30/2019 Western Kentucky University
12/20
anterior, slightly archedin profile
expanding fromanterior, no arch in
profile
anterior, arched inprofile
16. nasal
overgrowthabsent absent present
17. nasal sill or
dampresent absent absent
18. lower nasal
spinelarge and sharp small small
19. zygomatic
archesnarrow and retreating
medium to large and
retreatingprojecting
20. externalauditory meati
round round oval
21. palate shape triangular rectangular parabolic or horseshoe
shaped22. palate suture irregular irregular straight
23. occlusion slight overbite slight overbite edge-to-edge or even
24. central
incisorsblade shaped blade shaped shovel shaped
25. shape of
ascending ramusof mandible
pinched at midsection back slanted wide and vertical
26. projection of
ascending ramusof mandible
non-projecting projecting non-projecting
27. gonial angle slightly flared not flared slightly flared
28. chin profileprominent and
projectingrounded 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.
7/30/2019 Western Kentucky University
13/20
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
7/30/2019 Western Kentucky University
14/20
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 nasalbreadth 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 nodam 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 yourhand 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
7/30/2019 Western Kentucky University
15/20
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 checkBOTH 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 ofthe 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. Besure 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.
7/30/2019 Western Kentucky University
16/20
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).
7/30/2019 Western Kentucky University
17/20
7/30/2019 Western Kentucky University
18/20
7/30/2019 Western Kentucky University
19/20
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.
7/30/2019 Western Kentucky University
20/20