Analysis of Skeletal Remains – Worksheet

In this activity, skeletons will be examined for how they vary according to the following:

Sex (based on the pelvis & skull)

Ancestry (based on the maxilla, and other characteristics of the skull)

Age (based on general characteristics)

Height (calculated based on the length of individual bones)

Being able to determine Left and Right is also crucial to the practice of forensic anthropology, not only for

skeletal reconstruction, but also to determine the number of casualties. Reference to a complete skeleton is

helpful, but one is never around when you need one (as would happen if you are investigating a skeleton in the

woods). That will not be a part of this activity, but it easily could be.

SEX

One of the issues of concern to the forensic anthropologist is the sex of the human remains. There are several

things that may, on the surface, be useful to sex determination, but, on upon closer examination, are not very

useful. For example, females are, on average, shorter than males, but a short skeleton can easily be male. This is

due very simply to the fact that each sex follows a Gaussian distribution (a.k.a. a Bell Curve).

Image from http://www.bbc.co.uk/science/hottopics/intelligence/iq.shtml

As such, it is easily possible to have a female at the tall end of the height curve, and a male at the short end of

the height curve. The curves for sex overlap, for the most part, with the peak of each curve slightly off-set. It is

easy to say that the average height is shorter for females than it is for males, but that information is useless

when we examine individual skeletons.

DETERMINING SEX BY THE PELVIS

There are several ways to more accurately determine the sex of a skeleton. One of them is by examining the

pelvis, which can be identified accurately about 95% of the time.

Images from http://www.clipart.com

Original image from http://www.boneclones.com Original image from http://www.boneclones.com

Examine the pelvis above and highlight the feature Examine the pelvis above and highlight the feature

in each pair below: in each pair below:

Angle > 90 degrees or < 90 degrees Angle > 90 degrees or < 90 degrees

Sacrum Forward or Backward Sacrum Forward or Backward

Pelvic Outlet Small or Large Pelvic Outlet Small or Large

Ilia Close or Spread Ilia Close or Spread

Female or Male Female or Male

DETERMINING SEX BY THE SKULL

Another way is to examine the skull. This is still fairly accurate, but not as accurate as the pelvis. Forensic

anthropologists can accurately identify the skull somewhere between 85% and 90% of the times. This can be

complicated by several factors. If a skull is incomplete, then, of course, there is less to work from. Some of the

distinguishing characteristics, such as larger bone landmarks for muscle attachments in males, can be easily

confused with the landmarks of more athletic females. To put it simply, since the landmarks are often for the

attachment of muscles, the larger the muscles, or the more one uses the muscles, the larger the landmarks.

Landmarks Female Male

Chin Rounded Square

Mastoid Process

(Behind Ear) Small Large

External Occipital Protuberance

(Back of Skull)

Small

(Not Prominent)

Large

(Prominent)

General Anatomy Gracile (i.e., Graceful) Robust

Forehead Vertical Receding

Brow Ridges

(Location of Eyebrows) Slightly Developed Prominent

Muscle Lines Slightly Developed Prominent

Orbital Margins

(Edge of Eye Socket) Sharp Rounded

Angle of Ascending Ramus

(Back Corner of the Jaw) Obtuse Close to 90 degrees

Original images from http://www.boneclones.com

Choose the Appropriate Answer in Each Pair of Characteristics Below

Chin Rounded or Square Chin Rounded or Square

Mastoid Process Small or Large Mastoid Process Small or Large

Occipital Protuberance Small or Large Occipital Protuberance Small or Large

General Anatomy Gracile or Robust General Anatomy Gracile or Robust

Forehead Vertical or Receding Forehead Vertical or Receding

Brow Ridges Slight or Prominent Brow Ridges Slight or Prominent

Muscle Lines Slight or Prominent Muscle Lines Slight or Prominent

Orbital Margins Sharp or Rounded Orbital Margins Sharp or Rounded

Angle of Ramus 90 degrees or Obtuse Angle of Ramus 90 degrees or Obtuse

Sex Female or Male Sex Female or Male

Now that you have had some practice, what about this skull?

Choose the Appropriate Answer

Chin Rounded or Square

Mastoid Process Small or Large

Occipital Protuberance Small or Large

General Anatomy Gracile or Robust

Forehead Vertical or Receding

Brow Ridges Slight or Prominent

Muscle Lines Slight or Prominent

Orbital Margins Sharp or Rounded

Angle of Ramus 90 degrees or Obtuse

Sex Female or Male

ANCESTRY

There are several features that can be used to determine the ancestry of an individual. In terms of the skull, a

great place to start is the maxillary bone. The left and right maxillary bones form the roof of the mouth, contain

the upper 16 teeth in the adult (the upper 10 teeth in the child), and form the outline of the nasal cavity.

The arch of the maxilla can be found in three basic shapes: rectangular, triangular, and parabolic. Each of the

following three ancestries have their own shape: (1) African (Negroid) = rectangular, (2) European (Caucasoid)

= triangular, and (3) Asian (Mongoloid) = parabolic.

The incisors, as well, differ in their basic shape. The incisors fall into two basic categories, based on the shape

of the lingual (tongue) surface of the tooth. These two categories are: (1) shovel-shaped, and (2) spatulate, or

spatula-shaped. As there is more than one race with spatulate incisors, other indicators are necessary to

positively identify race, although this single feature can be used to eliminate one of the possibilities. Each of the

the following three races have their own shape: (1) African = spatulate , (2) European = spatulate , and (3)

Asian = shovel-shaped

Based upon both criteria, label the following maxilla according to ancestry:

Choose the Appropriate Answer in Each Pair of Characteristics Below

Arch Shape

Square, Triangular, or Parabolic

Arch Shape

Square, Triangular, or Parabolic

Arch Shape

Square, Triangular, or Parabolic

Incisor Spatulate or Shovel-shaped Incisor Spatulate or Shovel-

shaped

Incisor Spatulate or Shovel-

shaped

African Asian European African Asian European African Asian European

In addition to determining sex, there are characteristics of the skull that can be used to determine the ancestry of

an individual. Many of these features are quite subtle, and require detailed examination of the skull. A couple of

features, however, are more easily seen. For example, in people of African ancestry, the nasal opening is more

wide and squared. Another example is that of the zygomatic arch (or cheek bone), which is angled more

forward in people of Asian ancestry, thus giving the person a slightly more flattened face. Unfortunately, a true

examination of racial characteristics is not possible on a worksheet.

AGE

One way we can tell relative is by looking at the condition of the bones themselves, with the older bones being

more likely to be arthritic. Examine the bones below, and label which is arthritic (and therefore older), and

which is the younger:

Original image from http://www.boneclones.com

Choose the Appropriate Answer in Each Pair of Characteristics

Below

Arthritic Yes or No Arthritic Yes or No

Younger or Older Younger or Older

Another way to determine age is by looking at the development of the cranial sutures:

Images from http://www.clipart.com

Note, for example, that the adult skull has no remaining suture (called the frontal suture) in the middle of the

Frontal bone. Remember, also, that all the sutures ultimately become more filled-in ("closed") as we age.

Compare the two skulls below to determine which skull is from an adult, and which is from an adolescent:

Original images from http://www.boneclones.com

Choose the Appropriate Answer in Each Pair of Characteristics Below

Frontal Suture Present or Absent Frontal Suture Present or Absent

Other Sutures "Open" or "Closed" Other Sutures "Open" or "Closed"

Adolescent or Adult Adolescent or Adult

Can you see the fontanels in the image below? Note how many places in the infant skeleton are still made of

cartilage, which appears blue. This indicates how much of the skeleton is still developing.

Please note that the pelvis is still divided into the three parts: ilium, ischium, and pubis; these will ultimately

fuse into a single pelvic bone (a.k.a., Os coxa, or Innominate). Note the many bones in the sternum, which will

ultimately fuse into one. Remember that the total number of bones in the skeleton, 206, is based on an adult

skeleton. The actual number in an infant is much higher!

Please also note that there is a great deal of cartilage at the end of each of the long bones, an area called the

epiphysis (see the image below). (If each end is called the epiphysis, how do we show one end of the humerus

from the other end in the name? Easy: Proximal epiphysis& Distal epiphysis!) The cartilage at all the epiphyses

(pl.) indicates that a great deal of growth in long bones is actually happening at the ends (thus making the bones

longer. Another way to determine age is to look at the epiphysis (end) of a long bone (the shape of which should

be self-explanatory).

First of all, an x-ray is actually a film negative. When light (Don't forget that x-rays are a form of light!) hits

photographic film, it turns the film black; in making a print (i.e., making a negative of the negative, which is

therefore a positive), the image printed will look white. The more light, the darker the negative, and the

brighter the developed image. X-rays pass easily through muscle and most organs, but not through bone; this

will make the bones appear lighter in the negative (which works well for us, as bones are already white!). An x-

ray image (radiograph) of a child will reveal a dark area where the growth plates are still made of cartilage

(more x-rays can pass through cartilage, which is less dense, thus making a dark area); these areas are the

epiphyseal plates. An x-ray radiograph of an adult will reveal a white area where the growth plates have been

turned into bone (fewer x-rays can pass through bone, which is more dense, thus making a white line); these

areas are the epiphyseal lines. Examine the radiographs below, and determine whether they are from adults or

children:

Images are from

http://www.dartmouth.edu/~anatomy/knee/radiographs/radio3.html

Choose the Appropriate Answer in Each Pair of Characteristics Below

Epiphyseal Plate or Line Epiphyseal Plate or Line

Adult or Child Adult or Child

HEIGHT

Lastly, often a skeleton is incomplete. Despite this, it is still possible to calculate, with a certain amount of

accuracy, the height of a skeleton, even if the calculation is based upon a single bone! Apart from height,

average weight can be calculated based on not only the general size of the bones, but also by evidence of the

weight borne by the bones. These weight calculations, however, are too complex to demonstrate without

detailed examination of the bones, which obviously cannot be done on a paper worksheet.

Any of the major bones of the arm or leg can be used to determine height. The major bones of the arm are the

humerus, ulna, and radius. The major bones of the leg are the femur, tibia, and fibula. Given that not everyone's

arm to leg ratio is exact, height is usually estimated by using more than one bone, if possible. Granted, a

complete skeleton does not require calculation, but skeletons are not always complete, especially ancient

skeletons. The calculations we will be looking at will be of the femur, humerus, and radius.

SmartDraw Image

In order to calculate the height, in inches, follow the formulas below for each of the bones. Be sure to indicate

height not only in the total number of inches, but in terms of feet and inches (i.e., a person who is 62 inches is

also described as being 5 feet, 2 inches tall, or 5' 2"). NOTE: The calculations, of course, are different when

measurements are in centimeters.

Bone Formula for calculating Body Height (in inches)

Female Male

Femur Height equals (length of femur x 1.94) + 28.7 Height equals (length of femur x 1.88) + 32

Humerus Height equals (length of humerus x 2.8) + 28.1 Height equals (length of humerus x 2.9) + 27.8

Radius Height equals (length of radius x 3.3) + 32 Height equals (length of radius x 3.3) + 34

In order to calculate the height, in cm, as most of the world does, follow the slightly different formulas below

for each of the bones.

Bone

Formula for calculating Body Height (in cm)

Female Male

Femur Height equals (length of femur x 1.94) + 72.9 Height equals (length of femur x 1.88) + 81.3

Humerus Height equals (length of humerus x 2.8) + 71.4 Height equals (length of humerus x 2.9) + 70.6

Radius Height equals (length of radius x 3.3) + 81.3 Height equals (length of radius x 3.3) + 86.4

Now plug in the following numbers into the formula to determine the height to the nearest 1/2 inch (expressed

both as inches -- x" -- and as feet and inches -- x' + y") of the deceased:

Sex Bone Length Calculations

SHOW YOUR WORK!

Height

x"

in Inches

Height

x' + y"

(Feet +

Inches)

Multiply by

2.54 to get the

Height

in cm

Female Femur 17.9"

Male Femur 17.9"

NOTE: The same length is shown to illustrate the different calculations

required for the same measurements, depending on the sex of the deceased.

Female Humerus 11.5"

Male Humerus 11.5"

Female Radius 9.3"

Male Radius 9.3"

Sex Bone Length Calculations

SHOW YOUR WORK!

Height

in cm

Multiply by

0.3937 to get

the Height

in inches

Height in

Feet &

Inches

Female Femur 45.5 cm

Male Femur 45.5 cm

NOTE: The same length is shown to illustrate the different calculations

required for the same measurements, depending on the sex of the deceased.

Female Humerus 29.2 cm

Male Humerus 29.2 cm

Female Radius 23.6 cm

Male Radius 23.6 cm

QUESTIONS (Please answer in your own words, on your own paper, in complete sentences, and hand in

to Ms. G.)

1. What is the easiest way to determine the sex (using the skeleton) of an individual, and why?

2. What is the easiest way to tell (using the skeleton) whether a teenager is lying about her/his age, and

why?

3. Why can determining sex from a skull be difficult?

4. Why should a forensic anthropologist use more than one bone (if possible) to determine the height of an

individual?

5. What other issue is important to question four, especially if there is only one bone from which to work?