For unidentified human bone identification is important for both legal and humane reasons. Anthropology is defined as the application of the science of physical anthropology to the legal process. Forensic anthropologists have a set list of questions to answer:
1. Are the bones human?
2. How many individuals are represented?
3. How long ago did death occur?
4. What was the person’s age at death?
5. What was the person’s sex?
6. What was the person’s ancestry?
7. What was the person’s height?
8. Are there any identifying characteristics such as old injuries, disease, or unusual features?
9. What was the cause of death?
10. What was the manner of death (homicide, suicide, accidental, natural, or unknown)?
Forensic and physical anthropologists use the same standard techniques but forensic anthropologists use these techniques to identify human remains and detect the presence of crime. Bones can determine age, the time of death and the manner of death. Approximate age can be determined many different ways; one way is by the size and the development of the skull. This method is fairly accurate when it comes to fetuses. Analysis of the frontals, or soft spots, is another way to try to identify the approximate age of a fetus using the skull. As the skull becomes more developed the frontals become smaller and eventually become the sutures. As we age, the sutures fill in more and become harder. Besides using the skull, approximate age can sometimes be determined by the severity of arthritis or the inflammation of joints. As arthritis progresses it changes the shape of the bone. Also in the arthritis range is osteoarthritis which is when the joint’s cartilage becomes bone which results in a bigger bone. Finally comparative age can be determined by looking at the long bones in x-rays. In a child the area of bone growth is cartilage and in an x-ray it will appear as clear space and run close to parallel with the bone. In an adult the growth plate has turned completely to bone and in an x-ray will appear as white lines in the same location as the clear space in a child’s x-ray.
A person’s sex and ancestry can usually be determined by the skull. Most differences occur in the distance between the eyes and the shape of the teeth.
Approximate height can be determined by measurements of the bones. The best way to find approximate height is to measure the femur, which is the bone that runs from your hip to your knee. It is helpful to know the sex of the person because this factor affects the calculation of height.
To calculate the estimated height based on the person’s femur, first measure the femur in centimeters. If the subject is female, multiply the length by 2.47 and add 54.1 to arrive at the approximate height. If the subject is male, multiply by 2.32 and add 65.53. These calculations are accurate to within five centimeters.
Another common bone used to estimate height is the humerus. For this bone, the calculations are slightly different. For a female subject, multiply the length in centimeters by 3.08 and add 64.67. For a male subject, multiply the length by 2.89 and add 78.1. Again, these calculations are accurate to within five centimeters of the subject’s height.
A forensic anthropologist does not work alone to determine the age, time of death and manner of death. Forensic pathologists, forensic odontologists, forensic entomologists and homicide investigators can be consulted for their expertise. For example, an entomologist may be contacted for their expertise on bugs to help determine time of death, or a homicide detective can be called in to help determine cause of death and the manner of death.