Anthropology is the study of humans and humanity. "Forensic Anthropology" also examines humans, but as a means of identification of human remains, to discover legal evidence, to determine cause of death / traumaand many other applications.
Forensic anthropology can be used to to determine many variables, examples include:
- species
- cause of death*
- age
- gender
- health (prior to death)
- family ancestry
- height / morphology
- other physical factors
* ("cause of death" describes the events which terminate a life; "manner of death" is a legal descriptor including natural causes, homicide, accidental death, suicide or "causes unknown".)
Forensic anthropology can also examine human remains in a broad range of conditions - from recently deceased to highly advanced decomposition, although obviously the specific techniques to be employed will vary significantly. The study of human bone structure (osteology) plays a significant role since bone structures can remain largely intact over significant time intervals, and even provide significant information when all other tissues have been destroyed (dental records are often the only remaining identifier in cases where there has been a significant fire.
The primary focus for forensic anthropologists is what are described as "hard tissues". This includes bones (intact or fragmented), teeth, as well as cartilage (if available). A forensic anthropologist obviously needs skills in osteobiology / skeletal biology, but also may require what are traditionally thought of as "archeological" skills in order to locate, excavate and secure skeletal remains.
General information that is sought can include:
- Locate bones / physical remains at crime scene
- Identify whether or not the remains are human - there are many instances where animals bones are initially thought to be human remains
- Following on-site evidence collection of investigators, the skeletal remains will need to be safely transported back to the laboratory for analysis
- A biological profile which may include:
- physiological ancestry / race and gender
- age, height, weight and health prior to trauma event
- trauma causing mortality
Types of Trauma
There are three fundamental types of trauma: postmortem, perimortem and antemortem.
Postmortem Trauma - trauma events which have occurred after death. Postmortem trauma can be differentiated from pre-death (antemortem) trauma in several ways. First and foremost there is obviously no healing at injury sites after death - a strong indicator of postmortem injury. As well, bones desiccate significantly upon exposure to air, cau
sing them to be far more brittle than bones in a living individual, and often to stain / discolour in a noticeably different manner. Therefore, both visually and texturally there are therefore significant differences between skeletal trauma ante and postmortem.
Antemortem Trauma - trauma which has occurred prior to death. Antemortem trauma will show signs of healing on the bone structure. Furthermore, bones that have healed will likely have medical records (such as x-rays) which could provide a positive identification if no other is avaialble.
Perimortem Trauma - trauma events which occur close to, or at the time of death. Perimortem trauma is determined by a process of elimination. Skeletal remains which display trauma without healing (but also without a brittle texture and staining) indicate neither antemortem or postmortem injury, leaving only perimortem injury as the cause.
Specific Data
Height
Establishing a victim's height can be useful in many other aspects of forensics. Height data can help support BPA (blood pattern analysis), ballistics, relative location and other aspects of an investigation. The simples technique for determining height is to re-assemble the skeleton and add additional height (approximately 10.5 cm) to account for connective tissues and muscle mass.
In circumstances where incomplete skeletal remains are available there are specific bones which can be used as an estimate of height. In general, longer individual bones provide more accurate data. Multiplying the length of the human femur by 2.67 provides an estimate of height. This however can vary depending on age, gender, health and other factors.
Gender Determination
Pelvis / Hip Bones - a significant difference exists between male and female hip bones. Male hip bones are more narrowly spaced as compared to female hips, which have to have sufficient spacing for childbirth.
Skull - the human skull has three indicators of gender. These three groups of bones are all larger and more pronounced in males. Skull gender indicators include:
- Occular ridges (just above the eyes)
- Occiput - the bone at the rear base of the skull
- Lower ear - the bone located just below the ear
All three of these human skull bones are larger in most males.
Age Determination
Age can be approximated through careful examination of skeletal remains. Teeth are commonly used for identification of human remains against known dental records but also can provide valuable information independently.
Children have "baby" or "milk" teeth as young children. The presence of such teeth can be used as an approximation of age, although there are congenital / familial tendencies which can cause significant variation. The presence of "wisdom teeth" which typically appear at age 17-18 which can also be a useful indicator of general age.
Ossification - this refers to tendency of bones to fuse together and increase in relative hardness, thickness. There are hundreds of ossification sites in the human body providing strong evidence for aging a child or youth's skeleton.
Key Ossification Periods:
- Age 6 - formation of bone plates on outer radius (arm)
- Males age 17 - radius and lower bone plate fusion
- Females age 19 - radius and lower bone plate fusion
- Age 28 - cessation of collarbone growth / development
- Post 28 - gradual degradation of bones and joints
Other indicators include signs of arthritis in joints, knee deterioration, tooth / enamel decay For young children specifically, the skull has both sutures and a fontanel which close over time.
Bone Artifacts and Characterizing Injury
Over a lifetime the human body is subjected to numerous trauma and natural degradation. This phenomena is highly useful to a forensic anthropologist in several ways. General deterioration and "wear and tear" can be indicative of age, lifestyle and a wide range of other factors (such as those described above). However, some skeletal remains can provide key data based on specifc injuries, healing events or other trauma sustained over the individual's lifetime.
The nature of bone breakage occurring postmortem is significantly different that in a healthy individual - there is no healing in injuries incurred postmortem. Even the way bone breaks can be significantly different as it begins to desiccate. The nature of a weapon may also be revealed by specific styles of injuries to bone structures, be it a blunt trauma verses a bullet entry. The nature of the wound and presence or absence of bone chips or fragments may also be indicative of the nature of the weapon used or distance from the victim.
American Association of Physical Anthropologists: http://physanth.org/
