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 ancestry 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?

The sex of an individual is determined, when soft tissue is not present, by a number of skeletal indicators. Of course, the more indicators used to determine sex, the more accurate the results. However, a forensic anthropologist is analytically limited by the bones present and the condition of the bones.

We will look at several features of the pelvis, skull, and limb bones in determining sex. What we will do in this activity for sex determination does not cover all skeletal indicators of sex, but it will give you a good idea of how a forensic anthropologist determines the sex of an individual using the bones. The most accurate assessment of sex can be derived from the complete skeleton, followed in accuracy by the pelvis, skull, and then individual postcranial bones.

Remember that sex determination is very difficult for sub-adults because those features and characteristics are not fully formed, thus giving a more gracile appearance. Unless specified, the elements in the photos are Caucasoid.

The measurements used for this activity are not inclusive of all the measurements that are normally collected by anthropologists from complete specimens. The measurements used here are introduced and discussed in your text (Byers, 2011).

Assignment: Determination of Sex

Compare the elements (and/or measurements) in the activities below to the known pelvic bones and skulls in the reference materials. Based on the sex model, determine the sex for each specimen.

Assessment Dropbox.

Instructions:

You will identify the sex of three individuals in this assignment. Often, remains exhibit characteristics that can be attributed to both sexes. In these cases, assign the sex to the group that has a majority of traits.

Part I. Non-Metric Traits

Anthroposcopy, or the study of non-metric traits, is used in attributing sex. In this part, you will be looking at several different characteristics of the pelvis and the skull to estimate sex of two individuals.

The non-metric traits in the table below are a collection of the different methods that forensic anthropologists use. Your text covered the material as one set, but I have separated them here according to their developers. Note: there will be some overlap and there maybe one or two characteristics not described in your book (you should still be able to identify the characteristics by what you have learned).

Note: Zoom in the document if you want a closer look at a particular feature. You may have to look at multiple images to identify a trait.

Refer to the charactersitics in the Actvity Reference Materials and your textbook for help.

Pelvis 1

On the answer sheet, use the highlight function to highlight all the pelvic traits that you observe in Pelvis 1, and make a final count at the end. Then identify sex (and why) in the space following Table 1.

Figure 1 Medial view of Left ischiopubic ramus (left); Figure 2 Anterior view of Left os coxa (above)

Figure 3Lateral-Posterior view of Left os coxa

Figure 4 Anterior view of os coxea

Figure 5 Anterior view of Right subpubic concavity (above); Figure 6 Anterior view of Left pubis (below)

Figure 7 Distal view of Left os coxa showing sciatic notch (above)

Table 1 Sex Characteristics of the Pelvis

Trait	Male	Female	Intermediate/
			undetermined
Phenice(1969)	Not present/ Small	Present/ Large
Ventral Arc

Medial aspect of

Wide/Dull

Narrow

Ischiopubic Ramus                                                          and Sharp

Result:

Sutherland &                                                                      Narrow,               Wide,

Suchey (1991)

Pubic Body

rectangular        square

Subpubic Angle                           Narrow                     Wide

Result:

Trait                                                 Male                                                    Female

From Brothwell (1981);

Ubelaker (1978)

Illiac Blades (Illium)                    High, not flared (vertical)             Flared laterally, (low/flat)

Greater Sciatic Notch	Constricted, approx. 30° angle	Wide, approx. 60°
Preauricular Sulcus	Shallow, if present	Deep, if present
Obturator foramen	Large, ovoid	Small, triangular
Subpubic Angle	Acute	Obtuse
Pubis	Short	Long
Ventral Arc	Ridge not present	Ridge is present
Subpubic Concavity	Slight depression, or absent	Large concavity

Result:

Pelvis 1 Results:

Cranium 1

On the answer sheet, use the highlight function to highlight all the skull characteristics that you observe on cranium 1, and make a final count at the end. Then identify sex (and why) in the space following Figure 8.

Table 2 Characteristics of Male and Female Skulls

Trait   Male Female Frontal Bone   Steep, rugged,slanted Rounded, smooth Supraorbital Ridge/ Brow ridges Prominent, large Smooth, gracile, sharp       boarder, or none Supra-Orbital Margin   Rounded, blunt superior margins Sharp margins Size   Large and rugged Small and smooth   Chin     Broad, Flared>125°, wide, square   Pointed, Narrow <125°, constricted Mastoid Processes   Thick, thumb-like Smaller, finger-like Occipital Protuberance/ Nuchal Crest   Marked muscle ridges, thick, with hook Not marked, does not protrude   Result:         Cranium

From Krogman (1962:115);

Brothwell (1981:59)

Lateral (right) view of cranium 1

Anterior view of cranium 1

Cranium 1 Results:

Part II. Metric Traits – Cranial measurements

Like the discriminant functions used to attribute ancestry, discriminant functions can be used to separate between male and female using measurements of the skull.

Cranium 2

For this section, identify and enter the values in the appropriate rows for Cranium 2 into Table 6 below. Also enter in the appropriate discriminant function measurements (discriminant function of your choice) for White crania. Then identify sex (and why) in the space following Table 6.

Each measurement is multiplied by its coefficient, and all such calculations are summed to arrive at a function score. These scores are compared with the sectioning points in Table 5 to attribute sex.

Function values that fall below the sectioning point are female while those above the sectioning point are male.

Note that the functions use different sets of measurements. As stated in your text, this is to accommodate incomplete crania.

These measurements would under normal conditions be taken with sliding or spreading calipers.

Table 4 shows how your calculations should look like. The cranium measurements used for Table 4 belong to Black ancestry and using Discriminant Function 9.

Figure 10 Views of skull showing measurements used in discriminant functions

Table 3 Cranial Measurement Descriptions

Measurement	Description
BaPr	Basion to prosthion
ML	Maximum length: from the glabella to the occipital bone (measuring the greatest distance)
MB	Maximum Breadth: from highest points on squamosal suture (measuring the greatest distance)
BaBr	Basion to bregma
BaNa	Basion to nasion
BB	Bi-zygomatic breadth: perpendicular to the sagittal plane
NaAl	Nasion to lowest point in the alveolar border between central incisors
PB	Maximum breadth of the palate
LM	Length of the mastoid process (measured from the upper border of the external auditory meatus)

Note: All measurements should be recorded in mm

Table 4 Example of attributing sex using discriminant function 9

Measurement	Value		Coefficient		Calculation
BaPr	xxx	X		=	xxx
ML	188	X	3.533	=	664.204
MB	135	X	1.667	=	225.045
BaBr	140	X	0.867	=	121.38
BaNa	108	X	0.1	=	10.8
BB	142	X	8.7	=	1235.4
NaAl	xxx	X		=	xxx
PB	xxx	X		=	xxx
LM	30		14.367		431.01
Sum	———	—–	——————-		2687.839
Sectioning Point	———	—–	——————-		2515.91

Table 5 Discriminant Functions for Determining Sex of White and Black Crania

134

Table 6

Measurement BaPr ML MB BaBr BaNa BB NaAl PB LM	Value	X X X X X X X X X	Coefficient                             =                             =                             =                             =                             =                             =                             =                             =	Calculation
Sum Sectioning Point Discriminant Function Number:

Cranium 2 Results:

Part III. Final Assessment

Briefly write your conclusion (minimum 300 words) on the three methods used to attribute sex (skull metric vs. pelvic non-metric vs. skull non-metric). Which method did you think was more accurate? And why? Offer examples.

REFERENCES

Byers, Steven (2011) Introduction to Forensic Anthropology (4^th ed). Prentice Hall.

France, D. L. (2003) Lab Manual and Workbook for Physical Anthropology (5th ed.). West / Wadsworth. White, T. D. (1991) Human Osteology. Academic Press.