What is Forensic Osteology? Well it is the child of Physical Anthropology (study of the human physique) and Pathology (study of the processes causing death). Its grandparents were Medicine and Anatomy. Its other relatives are Paleontology (study of ancient humans and related species) and Zoology (study of animals). Forensic Osteology is one of the newer disciplines in forensic investigations. This youngster may call on any of his/ her relatives for help and expertise during an investigation. At times Physical Anthropology and Pathology may argue about who is in charge but in the end they usually co-operate to get the job done. Not so long ago Criminology approached Osteology and said "Hey, I could use your help". Osteology gave itself the title of forensic osteology.
Technically speaking Osteology is the study of bones. Forensic osteology is the study of bones as they relate to a crime. Many sources will define this as Human Osteology, Physical Anthropology or Forensic Pathology according to the source. I agree in part with some authors that a pathologist's experience in medical aspects and anatomy may be the best person for the job. However, few pathologist have experience in excavation of outdoor site were remains are located. As well, few Pathologists/medical examiners/coroners have extensive knowledge of the anatomy of animal remains. Even an experienced archeologist/anthropologist may seek a veterinarian or zoologist for further advice on remains which are hard to identify.
Finding the Remains
In most cases it is not a Physical Anthropologist or an Osteologist that finds the remains. Frequently it is a hiker, hunter or people doing excavation for construction purposes that find bones. Sometimes they contact the police or a local museum or university to help identify the bones. If enough suspicion about the bones is raised the police may be asked to conduct a search or excavation. In turn they may contact a Forensic Anthropologist, Search and Rescue personnel or the Medical Examiner depending on the local policies.
No matter what the circumstances, if an outside burial is to be examined someone experience in archeological techniques should be consulted. There is no point in sending search and rescue personnel to collect bones and throw them into a body bag. I know this is often done both in Canada and the U.S. but it only serves to confuse the scene especially in areas which may contain animal and human bone. As well, by co-mingling remains for transport the bones may sustain damage which further confuses the analysis of pre and post mortem damage. Finally it is somewhat unethical to co-mingle remains because it may cause further trauma to the surviving family members.
Documentation and Removal of the Remains
I have repeated this next section on documentation so many times I should sound like a broken record by now. That is if there is anyone out there that remembers what a record is. Maybe I should say a scratched C.D. or damaged MPV player for those younger readers. Well you get the point I am sure.
When remains are discovered unless there is an immediate threat due to weather or other factors there should be no panic to execute a speedy removal. The entire scene has to be properly mapped, photographed and documented as to scope. Although the find may be exciting the people or person in question is not going anywhere so it is advisable to do a systematic analysis of the scene.
Every scene involves different circumstances and will require modified approaches. The remains may be located in a number of ways. Remote sensing, sonar, radar, heat sensing and aerial photography are mechanical methods of finding remains. As well, scent dogs, divers and search and rescue teams may be employed in a more physical type effort to discover remains. There are two main methods of conducting the removal of suspected human remains (White & Folkens, 2006).
Once the remains have been located the principal investigator must determine whether the remains are scattered on the surface or whether the remains are buried in a relatively intact state. Of course there are some cases of dismemberment which involve buried intact sections which are scattered but this is rare.
Scattered surface remains can be documented as a sketch using stationary objects as landmarks or if they are in a relatively small area a grind created with string can be used. Some agencies use Global Positioning Systems (Foothills Search & Rescue, 2005). Scatter surface remains can be marked with flags or other visible markers and added to the sketch or grid before removal.
Buried remains involve a different sort of collection procedure. The same grid is used but the removal of the remains is somewhat trickier. If a burial site is located the remains must by removed in one of three ways. Under no circumstances should heavy machinery be used to excavate burial sites.
The first method of removal is used when an intact burial is discovered. The earth around the burial is removed using a series of shovels and trowels in descending size as you near the actual bones. In the final stages of exposing the remains brushes are used. When the intact remains have been exposed they can be photographed with an indicator of size and orientation in the picture. Removal of the remains can then proceed in two ways. The bones can be removed one by one and packaged separately with labeling indicated the type of bone and the side of the body from which it came. If inspection of the pelvic region indicates the presence of fetal remains or if the remains appear to be from a child then another method can be employed. Juvenile and fetal remains contain many very tiny bones which have not yet fused with others and are extremely easily lost into the soil around the remains. In this case it is advisable to employ a method used originally by Paleontologists to remove fragile dinosaur bones.
The remains are exposed and then a pedestal of earth is made by excavating the earth around the remains. Wet paper towel is draped over the remains which are then wrapped in burlap. The remains are then coated in plaster. As the plaster dries the remaining bottom sections are slowly encased and the entire burial is transported to the lab as a whole (White & Folkens, 2005). Even using this method the surrounding area should be processed using a series of ever diminishing screen sizes to check for small bones and other evidence such as the remains of clothing.
The Osteologist
The questions which the Forensic Osteologist will be asked to try to answer are as follows.
- Is it Human?
- How long has the person been dead?
- How many individuals are associated with the remains?
- What is the age, sex, height and possible racial affiliation of the person or persons in question?
- Do the remains show and signs of pathological conditions or medical treatments which might identify the individual's age, or antiquity?
One of the most common questions I am asked is how to tell whether a bone is human or not. This is also the first priority of the Osteologist whether it is an Anthropologist or any of the other fields involved in this question. The straight answer is twofold. If there are long bones or a skull which are intact it can be fairly straight forward. If the bones are fragmented it becomes increasingly more difficult to judge. Human bones are quit variable in there size and shape which can also complicate the process. I once saw a photograph of the skeleton of a man named Joseph Merrick who most people would know as the "Elephant Man". If I had unearthed his remains without knowing his history I think I would have been skeptical as to whether they where of human origin. Bears paws are often mistaken for human feet. Pet rabbits and Guinea pigs are also mistaken for human fetal remains.
The questions to be answered by the Forensic Osteologist are first is it human. If the answer is yes then what is the antiquity of the burial. Generally in forensic investigations 50-75 years antiquity is the cut off time (Donilak, Matsches & Lew, 2005). Forensic investigations focus on solving a crime. If the burial or death occurred more than 50-75 years ago it is unlikely that and criminal prosecution will occur. However, the relatives of a missing person may still have interest in knowing if the remains are likely to have been there missing loved one.
Antiquity can be difficult to establish. It is often dependant on the retrieval of non biological artifacts such as clothing, buttons, dental implants or work and medical implants or procedures (Donilak, Matsches & Lew, 2005). Each of these items can usually be assigned a manufacture date or a time period in which it was used.
What is a Bone?
Bone is made up of proteins and minerals. It is the strongest biological material in terms of load bearing capabilities (White and Folkner, 2005). The skeleton as a whole is a series of levers (bones) connected by hinges (joints) and controlled by pullies (tendons and muscle.
The actual components of bone are called Osteons and are sometimes counted microscopically to help determine the age of an individual since the numbers decrease with age.
Adult bones are made up of two main types of bone. Cortical or compact bone is found in the walls and external surfaces of bone shafts. As well it is found at the sites at which cartilage would normally be attached. The second type of bone is spongy and is found at the end of long and short bones (White and Folkner, 2005).
The following information was taken from (www.medlib.med.utah.edu/kw/osteo/index2.html)
There are four main bone shapes. The first are the "long bones". These include the bones of the legs (Tibia, Fibia and Femur) and the bones of the arms (Humerus, Radius and Ulna). Long bones have hollow shaft and are jointed at both ends.
Second, are the "Short bones" which include all of the metacarpals and phalanges (hands) and all of the metatarsals and phalanges (feet). In this group is also the clavicle or collar bone. Short bones are hollow and jointed at both ends.
The third category is the "Flat Bones". Flat bones include the Innominate (upper portion of the pelvis), the Scapula (shoulder blade), the ribs and the sternum. As the name implies these bones are flat with broad surfaces.
Finally there are the "Irregular bones" which include the entire vertabral column, 8 carpal bones, 7 tarsal bones and the patella (knee cap).
One of the common questions I get asked is "How many bones are we looking for?" My standard answer is " I don't know." Of course the person asking always looks a bit bewildered at first. They look at me with a "but you are supposed to know" look. I then give in and explain that unless you know the age of the person whos remains you are recovering you will not know the number of bones you are looking for. A fetus has somewhere between 275 and 300 bones while a baby or infant will have 275 or les depending on the age. An adult human has 206 bones. (taken from www.bbc.co.uk/science/humanbody/factfiles/bonegrowth/femur.shmtl (2006))
Age Determination
At the end of many bones there is an area known as the epiphysis or epiphyseal plate. As a person ages these plates ossify and become fused to the adjoining bone. The fusion of these plates and the adjoining bone occurs at a fairly predictable rate in most people. Most plates and bone are fused by the time a person reaches about 25 years of age. After 25 the bones begin to show loss in density and wear patterns.
Adults
In adults the pelvis and skull are frequently used to estimate age. As well, the shape of the ends of the ribs and the pubic symphysis may also be used to estimate age. Degenerative diseases such as osteoporosis and arthritis may be useful in determining if the remains are from an adult or youth.
In youth the pubic symphysis appears rippled. As the person ages it become smooth so that at age 50 the ripples have generally disappeared. The degree of rippling is rated or scored using a method called the Todd Method with a 1-10 scoring system.
The skull is often used as a good indicator of age because the sutures which join the various bones of the skull fuse at a know rate according to age. Keep in mind though that there is always a margin of error and that individuals mature at different rates as do each gender. The skull is useful because unlike long bones which complete ossification at around 25 years of age the sutures of the skull continue to fuse throughout life at various locations. However, the age at which the sutures close may vary according to genetic predisposition, nutrition and disease. Generally there are 17 sites on the skull which are graded from 1-4 as to the degree of closure (Donilak, Matsches & Lew, 2005).
Children and Teens
Some sources suggest that measurement of the long bones can be used to estimate age in young people. Other sources refute this idea citing the extreme variability in growth and stature. Measurement of the long bones seems to be accurate in fetal skeletons and very young children. The accuracy diminishes as the child ages. After the age of four or five the long bone length is not a good predictor of age.
A more reliable method of estimating age is to examine the degree and sites of epiphyseal fusion. It has be noted that females show 25% more advanced ossification at the same age as there male counterparts. This puts the maturity rate of females about two years in advance of males. This fact then requires the examiner to know the sex of the remains before and accurate age can be estimated.
The most accurate method in determining the age from skeletal remains is to examine the dentition. Just as with epiphyseal fusion teeth erupt at a fairly standard rate. At birth the margin of error is +/- 2 months. By the age of 15 the margin of error increases to +/- 3 years. Again the sex and the variable rates of maturity between the two can create significant error. It is advisable when examining the remains of children to try to determine the sex first.
In the next issue I will examine how to determine age at death from skeletal remains.
| < Prev | Next > |
|---|
