The next most reliable method is to examine the skull's features. In general the female skull exhibits smoother more rounded features and is somewhat smaller. A male's skull typically has a bony ridge that runs across the brow just above the eye sockets. This feature can be quite pronounced or barely visible. In males, the lower jaw bone is squarer and the ends of the lower jaw where it attaches to the upper portion of the skull span a wider distance. The male jaw bone projects outward, while a female's slopes back slightly. If a skull's eye socket surface is rough it is female; if it is smooth it is male. On the back of the male skull, there is a protrusion that makes the skull appear rounded. Female skulls have a flattened area that starts at the crown and extends about half way down the back of the skull.What is the victim's race?
A forensic examiner also may be asked to predict the racial affiliation of the remains.
Three main categories are used to define racial affiliation: Caucasian (white), Negroid (black) and Mongoloid (includes Asian, Native American, Hispanic, some Middle Eastern and some Eastern European). Imagine a skull viewed from the side, then imagine a vertical line that starts at the forehead and runs straight down toward the chin. This is known as the vertical plane of the face. From this area, it is possible to guess the race of the human skeleton. Donilak, Matshes and Lew report the differences between the three as follows:
- Caucasian. The nasal bone extends perpendicular to the vertical plane. 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 outward from the vertical plane. The upper margins of the eye socket may appear to slope away from the nasal opening. The eye socket appears to recede from the vertical plane. The lower jaw bones (not the teeth) have a square appearance. 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 are straighter than in Negroid or Mongoloid skulls.
- Mongoloid. The nasal root slopes back into the nasal opening. The facial bones tend to be oriented along the vertical plane. The nasal opening 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. The zygomatic arches or cheek bones are prominent. The incisor teeth tend to be fairly thick. The back surface of the teeth may have prominent depressions, giving them a spoon shape. The sutures are generally more complex than in Caucasians. The palate is a half-circle shape.
- Negroid. The upper and lower jaws project outward from the vertical plane. The nasal opening lacks the pinched upper portion typical in Caucasians but is not as rounded as in Mongoloids. There is a prominent nasal gutter, which is the depression below the nasal opening. The nasal opening is square. The cheek bones tend to slope back from the vertical plane giving them a sunken appearance. The palate is rectangular in shape. The sutures of the skull tend to be less complex than in Mongoloids but not as straight as in Caucasians.
A forensic osteologist also may determine whether there has been any damage, both before and after death, to the bones. Approximately 80-90 percent of skeletal remains will show evidence of trauma, infection or arthritis, reports anthropologist Sherry Ortner.
Signs of infectious disease can help determine the area of the world from which the person came, and his or her general health at the time of death. For instance, remains that show an old healed ossification due to a disease such as leprosy can indicate the victim originated from parts of the world where the affliction is common. If the damage to the bone is severe, it can indicate that in life, the person walked with a limp or was disfigured in some way.
Trauma to bone can happen in many ways, report Donilak, Matshes and Lew. Fractures are common and can occur either through stress, blunt force or sharp force. Ortner reports stress fractures can be from weight or torsion; blunt force injuries take place when the bone is struck with enough force to break it, such as a car accident or a strike from a baseball bat or other weapon; and sharp force fractures occur when the bone is pierced with a bullet, knife or other sharp object.
The most common question is whether the fracture occurred before or after death. Ortner reports damaged or broken bones show signs of healing about a week after injury. If healing has begun or has already taken place, the injury did not occur at the time of death. A lack of healing indicates the injury occurred less than a week before death, and unhealed fractures of the arms and wrists may be defense wounds.