I am well aware there are extremely technical medical terms for the bones I am going to describe. I thought that it is much easier to read an article and absorb the information when you are not fighting a bunch of unknown terms. Therefore, as usual, I have reverted to terms like "cheek bone" or "thigh bone" to make things more enjoyable to read.
Part Two
In the last addition I finished with discussing the common methods used to determine the age of skeletal remains. I discussed the difficulties in determining age especially if it involves immature remains. Put more simply it is far more difficult to determine the age of a child based on only skeletal remains. Simply put boys and girls develop physiologically and skeletally at different rates. It is there for important to try to determine the sex of the individual before giving and age estimate. For children under the age of about 18 the best way to determine an approximate age is to study the pattern of eruption of the teeth. Even using this technique the approximation can be +\- 2 years as the child grows older ( White & Folkens, 2005)(Bowers, 2005). Determining the gender of the remains can be crucial in narrowing this field.
Determining Sex (gender)
Determining gender in adult skeletal remains is said to be one of the easier tasked asked of a forensic osteologist, pathologist or forensic Anthropologist. When the hip bones, skull or an entire skeleton is present some researchers estimate the accuracy at 95%. When only the skull is present the accuracy drops a bit but still stands at 80-92%. Even if the skull and hip bones are not present it is possible to estimate given the differences in the configuration of the female and male joints of the knees and elbows (Donilak, Matshes & Lew, 2005).
In general males have more robust bones and more prominent muscle attachments than females. This however may not always be true. I have only to think of myself at 5 feet and built slightly (bone wise that is) and my best friend who is over 6 feet tall and built like a brick (you know the rest).
Even given these differences in stature the female sacrum(tail bone area) is wider than in the male. The pelvic outlet is oval in response to the process of childbirth. Simply, those women whose pelvic outlet was narrow tended to die in childbirth. This caused an evolutionary selective process for women with oval pelvic outlets and generally wider hips.
There is a position on the hip or pelvic bone known as the Sciatic Notch. This is where the "rule of thumb" literally applies. In a female's pelvic bones if you place you thumb in this notch and you can move it back and forth this indicates it is a female. If your thumb is restricted and seems to fit into the notch this indicates male. In females the shape if the notch is closer to a half circle where as in males it is more oval shaped (Donilak, Matshes & Lew, 2005).
A quick test to determine gender can be done but roughly measuring the angle of the bones in the sub pubic area. By holding ones index finger up and then extending the thumb to the side one can roughly create a 90 degree angle. This angle can determine the gender associated with skeletal remains. With the index finger placed against the top outer edge of the sub pubic bones and the thumb extend if the remains belong to a male the thumb should touch the lower portion of the bone. If the remains are from a female the lower portion of the bone will slope away from the thumb (Donilak, Matshes & Lew, 2005).
In women who have had children there is a pitting or rippling on the surface of the pubis. Before and during labor the bones of a woman "soften". The rippling seen on the pubis may be caused by the infant's passage under pressure through this area while the bones are soft. This ripple appearance (known as dorsal pitting) of the pubis will tell an investigator that the remains are from a female or childbearing age. This feature will not indicate the number of children the woman may have had. As well there is some speculation that dorsal pitting can be caused by increases in weight which causes changes to the pelvic region (Donilak, Matshes & Lew, 2005).
If the pelvic bones are not available for study the next most reliable method is to study the features of the skull. In general the female skull exhibits smoother more rounded features. It is often smaller than the male skull. For those of you thinking of a joke at this moment this does have do with less brain capacity.
One of the most obvious indications of a skull belonging to a male is the presence of a boney ridge which runs across the brow just above the eye sockets. This feature can be quite pronounced or barely visible. As with everything scientific or otherwise there is always an exception to the rule, however, this feature is usually attributed to males.
In males the lower jaw bone tends to be squarer than in females and the ends of the lower jaw where it attaches to the upper portion of the skull tend to span a wider distance. The male jaw bone tends to project out with a square chin. A female's lower jaw tends to slope slightly back toward the vertical plane of the face.
The eye sockets of a skull can be tested by simply running a finger along the upper edge of the eye socket. If the surface is rough it is female. If it is smooth it is male.
On the back of the male skull there is a protrusion which makes the skull appear rounded. Female skulls have a flattened area which starts at the crown and extends about half way down the back of the skull.
Racial Affiliation
One of the other things a Forensic Osteologist may be asked to determine is the likely racial affiliation associated with the remains. I have always thought that in countries like Canada and the U.S. where the population has arrived from every corner of the world and often inter married that assigning racial affiliation could be next to impossible. However, attempts are still made at a "best guess".
The three main categories used to define racial affiliation are Caucasian (white), Negroid (black) and Mongoloid (includes Asian, Native American, Hispanic some areas of the Middle East and parts of Eastern Europe). Most of us are capable if looking at a person and determining what a person racial affiliation is by their facial features. A person's facial features are determined by the underlying structure of the bones of the skull. The shape of the ears or the nose and the complexion may not be reflected in the structure of the skull but the general features are.
Please note that the racial features described here are broad generalization and by no means cover all of the minute differences in bone structure between the three main categories of race.
If you can imagine a skull viewed from the side and then imagine a vertical line which starts at the forehead and runs straight down toward the chin this is known as the vertical plane of the face.
Caucasian
In people classed as Caucasian the nasal bone extend perpendicular to the vertical plane of the face.
The top of the nasal opening has a pinched appearance. At the base of the nasal opening there is what is called a 'nasal spine' which protrudes outwards from the vertical plane. The upper margins of the eye socket may appear to slope away from the nasal opening (Donilak, Matshes & Lew, 2005). The eye socket may have the appearance of receding from the vertical plane.
The lower jaw bones (not the teeth) has a square appearance. The shape of the palate is generally v shaped. The muscle attachment sites on the skull are more pronounced in Caucasians than in the other races. The sutures of the skull tend to be straighter than in Negroid or Mongoloid skulls (Donilak, Matshes & Lew, 2005).
Mongoloid
As opposed to Caucasians which have projecting nasal spine the nasal root in people of Mongolian descent slopes back into the nasal opening. The facial bones tend to be oriented along the vertical plane. The nasal opening also known as the Fossa is generally wider than in Caucasians.
The upper margins of the eye socket (orbital opening) can either appear round or square but do not slope downward as in Caucasians.
The zygomatic arches or cheek bones are prominent. Some Asian populations have a genetic predisposition for the bones which make up the zygomatic arch to be divided by sutures into two or even three parts. This is associated with people from Japan and parts of China (White & Folkens, 2005).
Another feature of the skull commonly but not exclusively associated with people of Mongoloid descent is the shape of the incisors. The incisors are the top and bottom four front teeth. In Mongoloid populations these teeth tend to be fairly thick. The back surface of the teeth may have prominent depressions giving the tooth a spoon shape (White & Folkens, 2005) (Donilak, Matshes & Lew, 2005).
The sutures of the skull are generally more complex than in Caucasians. The palate is a half circle shape (Donilak, Matshes & Lew, 2005).
Negroid
Persons of Negroid descent are sometimes referred to as being of Sub Saharan descent. However given the long and world wide dispersal of people for the continent of Africa this term can be misleading.
In people of Negroid descent the upper and lower jaws tend to project outward from the vertical plane (Donilak, Matshes & Lew, 2005).
The nasal opening lacks the pinched upper portion typical in Caucasians but is not as rounded as in Mongoloids. The feature most commonly associated with people of Negroid descent is a prominent nasal gutter. The nasal gutter is the depression below the nasal opening. The nasal opening is described as square (Donilak, Matshes & Lew, 2005).
The cheek bones tend to slope back from the vertical plane giving them a sunken appearance. In life this gives the person the appearance of cheeks bones that stick out at the front of the vertical plane (Donilak, Matshes & Lew, 2005).
The palate may be described as rectangular.
The sutures of the skull tend to be less complex than in Mongoloids but not as straight as in Caucasians (Donilak, Matshes & Lew, 2005).
Disease, Trauma And Other Changes To Bone Either Pre Or Post Mortem
One of the other things a Forensic Osteologist may be asked to examine is the presence of damage to the bones. Damage can be caused before or after death. Damage may include accidental or intentional trauma, disease and infection or wear caused by aging. Interestingly there are also some changes to bone which occur during pregnancy and after menopause in women (Ortner, 2003). These changes to bone can be extremely helpful in determining both the sex of a skeleton and the approximate age.
Many of the books written about Osteology deal with burials and skeletal remains of antiquity. However, a lot of the findings can be applied to modern forensic investigations. The estimation of the evidence available for recovery in an Osteological investigation is a follows. Approximately 80 to 90 % of skeletal remains will show evidence of either trauma, infection or arthritis (Ortner, 2003). Trauma may be pre or post mortem (before or after death).
Signs of infectious disease can help investigators determine the area of the world from which the person came and the general health including posture and gait of the person. For instance remains that show and old healed ossification of the bone due to a specific disease such as Leprosy can indicate origin from an area of the world where this disease is common. As well, if the damage to the bone is severe it can indicate that in life he/she may have walked with a limp or been disfigure in some way. All of these things can aid in the identification of the person and add to a guess as to race and age.
Finally signs indicating age can be found by observing the damage to bone. Arthritis is a common indicator of age although is can occur at any age. Osteoporosis is another indicator of age. Changes to bone which occur in women of childbearing age and after menopause can also aid in the estimation of age (Ortner, 2003).
This again is a much generalized description of some of the types of trauma and diseases which can cause changes to bone. It is by no means comprehensive.
Trauma
Trauma to bone can occur in many ways. Fractures are common and can occur either through stress or blunt force or sharp force (Donilak, Matshes & Lew, 2005). Stress fractures can be from weigh or torsion. Blunt force injuries occur when the bone is struck with enough force to break it. Car accident, attacks with fists, base ball bats and other weapons can cause blunt force fracture. Sharp force fractures occur when the bone is pierced with a bullet, knife or other sharp object (Ortner, 2003).
The most common question for a forensic osteologist is whether the fracture occurred before or after death. In other words in a forensic investigation it is helpful to know if the injuries where as a result of a crime or where they sustained sometime before death. Even if the injuries where sustained before death identifying them can be useful in determining the identity of the remains.
Bones which have been broken or damaged tend to show signs of healing about a week after they occur (Ortner, 2003). So in the case of fractures, knife marks, bullet wounds and other trauma to the bone if healing has occurred or started to occur one can say that the injury did not occur at the time of death. Lack of healing can indicate that the injury occurred less than a week before death. Unhealed fractures of the arms and wrists may also be defense wounds (Ortner, 2003).
In the case of spousal or child abuse there may be many healed fractures which may not be the cause of death but can indicate long term abuse. Some fractures occur naturally as the result of disease such as Osteoporosis. Again this can be a clue as to age, gender and general health of the individual.
So called fresh or 'Green" bone still retains a lot of the moisture in it and breaks in a different manner than a dry brittle bone. It is possible the microscopically examine bone to observe the stress fractures and determine whether the bone was damaged at or around the time of death or whether the damage occurred much later.
Old healed fractures may show signs of ossification around the injury site. Some professions can be associated with multiple fractures which have healed. Professional wrestlers, football players and rodeo riders come to mind. Again, knowing the medical and work history of the possible victim in a forensic investigation can help narrow down the identity of the person.
It is quit possible to mistake the signs and damaged caused by disease as signs of trauma. Therefore the Osteologist should posses some working knowledge of the patterns of bone damage caused by both trauma and disease.
Fracture may also occur due to certain medical or dental procedures. It is good to know the medical history of a missing person when trying to correlate remains with actual missing persons.
The diseases which can cause damage to bone are hugely varied. Some will not indicate the cause of death but many can narrow down the age, origin (geographical region) and the possible physical impairment of the person involved. In the next issue I will examine these conditions and there implications in forensic investigations.
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