Forensic Anthropology

The practice of forensic anthropology centers on the assessment of every aspect of skeletonized human remains in a medicolegal context for the purpose of establishing identity and, where possible, the cause of death and circumstances surrounding this event. It also encompasses facial image analysis, reconstruction, identification, and comparison of both the living and the dead.

Identification: Degrees of Certainty	Forensic Taphonomy	Demographic Characteristics	Personal Identification	Cause of Death
Possible Indeterminate Positive Identification	Time since death Burned bones	Age   Sex Race Stature and build	Individualization Facial imaging Superimposition Photo Comparison Facial Reconstruction	Disease Trauma

If there is nothing to rule out a potential match, the degree of certainty of an identification depends on the accuracy of the techniques and the presence of indisputable factors of individualization.

A match is “possible” if there is no major incompatibility that would exclude an individual from consideration. However, it must be emphasized that, while this assignment prevents immediate exclusion, it does not imply probability. A judgment of “possible” merely makes this individual eligible for further, more rigorous and specialized testing. Numerous prospective matches survive initial screening, but most of these will wind up in the “indeterminate” category. This is due to the fact that a large number of very similar features are shared by the members of any given age, sex, race group, or nationality, and thus cannot be deemed diagnostic of identity. General examples include pattern baldness, squared jaw, brown eyes, pug nose, and ear protrusion. Population-specific features such as alveolar prognathism in blacks, shovel shaped incisors in American Indians, and brachycephaly in whites are also not definitive. If no idiosyncratic characteristics or factors of individualization can be isolated and matched, the comparison can only be considered “indeterminate or inconclusive”. A positive identification can only be declared if there is absolutely no contradiction or doubt. This conclusion can only be reached based on the presence of unique factors of individualization. Taphonomic analysis traces events following the death of an organism to explain the condition of the remains. Numerous factors must be considered, including decomposition, animal predation and scattering, weathering and temperature variation, burial, submersion in water, erosion, burning, etc. Establishing when death occurred is one of the key determinations to make. It is rarely easy to estimate time since death precisely, and this determination gets more difficult with each passing hour. The forensic anthropologist is not usually called in on a case until decomposition or mutilation renders a victim unrecognizable and obliterates other identifying features. The degree of decomposition and sequence of insect infestation yield important clues but can only be interpreted properly if the examiner is familiar with how factors such as temperature and burial conditions affect the rate of these processes. For example, cold, coverings, and burial retard deterioration; heat, humidity, and exposure accelerate it. Even wily criminals on television are imbued with a smattering of this knowledge and attempt to mislead authorities by storing a body in a freezer to alter the apparent time of death. There are many forensic situations where this is vital, ranging from fatal building fires to car or plane crashes to attempts to destroy the body of a murder victim. The color and texture of a bone gives important clues to the heat and intensity of the blaze, as well as the approximate duration of exposure. Limited or indirect exposure to the heat source may produce only streaks of soot or yellow/brown discoloration, while direct, intense exposure will cause cracking and char or blacken the bones. If burning is direct and prolonged, only white ash may remain. A skeleton or even a single bone may show various levels of destruction based on position relative to the fire. The burning process also causes drying and shrinkage, thus distorting the size, weight, and shape of the bone. All skeletal assessments are acknowledged  as the “big four” — age, sex, race, and stature. Each characteristic narrows the pool of possible “matches” considerably — sex alone cuts it by half. If a skeleton is complete and undamaged, these attributes can be assessed with great accuracy. Using the latest techniques, sex can be determined with certainty, age estimated to within about 5 years, and stature approximated with a standard deviation of about 1.5” (3.5 cm). Assignment to the Caucasoid, Mongoloid, or Negroid race group can be accomplished with a high degree of certainty in the absence of admixture.

skeleton

During the early years of growth and development, the skeleton undergoes an orderly sequence of changes beginning with the formation and eruption of deciduous teeth and their replacement with permanent dentition by about the age of 12 years (excluding third molars). Although the timing of this process varies somewhat by sex, race, and health factors, age at death can be estimated to within 1 year in a normal subadult. Once growth is complete, age estimation becomes much more difficult because postmaturity age changes are subtle, irregular, and often highly variable from one individual to the next because remodeling rates and patterns are sensitive to a myriad of internal and external factors. Thus, there is a great deal of variation in the aging process itself, as well as in how it is reflected in the body. Even among the living there are always individuals who “look” much older or younger than their chronological age. It is the same, if not worse, in the skeleton.

Dental record & Human Teeth

Age changes can also be detected in long bones, but only radiographically or histologically. X-rays can reveal alterations in bone density that reflect the thinning that occurs with advancing age, but not with any degree of exactitude. Changes can also be observed at the cellular level based on histomorphometric analysis of a cross-section of long bone or rib. Teeth can also be thin sectioned for age assessment. Several features can be subjected to regression analyses. Scanning electron microscopy is used to quantify incremental growth layers in the dental cementum. This approach was originated by wildlife biologists and was only recently attempted on humans.

Cranial morphology

A thorough knowledge of cranial morphology can allow experts to

approach 90 to 95% accuracy. However, the observer must be familiar with population-specific variants because sex-linked characteristics vary from one group to another. In general, however, males tend to have rougher bones with larger crests and ridges, because these are often sites of muscle attachment.

Race may be defined as a rough classificatory mechanism for biological characteristics. There are three major race groups to which most people may be assigned: Caucasoid, Mongoloid, and Negroid. However, there will always be equivocal cases because of admixture. Almost every bone contributes to the overall stature of an individual; however, the relative contribution varies greatly. Singularly and collectively, the femur and tibia are the most important components of height. In contrast, a foot bone has very little input. Therefore, the best assessment of height is obtained from regression formulae derived from femoral and tibial lengths. These equations have been calculated for all of the long bones — even though an arm bone will not be as accurate as one from the leg, it may be the only part found. Attempts have been made to increase accuracy by using the combined contributions of multiple bones. Skeletal biologists and forensic anthropologists are often confronted with damaged bones, formulae have been devised to estimate stature from fragmentary remains. Establishing identity is not limited to skeletal remains. It is becoming increasingly important to be able to determine if two or more photographs depict the same individual. Photo-to-photo comparison entails the comparison of photographic images taken at different times under different conditions. This relatively new type of analysis relies on both metric and morphologic assessment and comparison of facial features. In any type of facial reconstruction, once the average tissue thicknesses are calculated and bony contours followed, many remaining details are left to conjecture because the skull does not provide all the indicators necessary to predict every soft tissue formation. Even the most skilled practitioner cannot determine such vital features as fatness, hair color or style, exact flesh tones, facial hair, or if a person looked older or younger than his chronological age. One of the most challenging issues is the attempt to match pictures of the same person at various ages. There appear to be two types of morphological features: (1) those that are clearly vulnerable to the effects of age, and (2) those that remain relatively stable throughout adulthood. The manifestations of the aging process and the rates at which they occur vary greatly from one individual to another because there are so many genetic and environmental factors involved. This makes it impossible to predict all but the most general trends. To complicate matters further, changes over time are not all due to aging; some can be linked to alterations in lifestyle and health, such as fluctuations in nutrition, physical activity, smoking, exposure to sun … .

Forensic anthropologists can sometimes determine the cause of death, but only if evidence of trauma or disease is registered in the bones. The expert must first be able to distinguish antemortem lesions that occurred during life from perimortem trauma at the time of death and postmortem destruction after death. If projectiles (bullets, shotgun pellets, arrow heads, etc.) or their characteristic imprints are embedded in the bones, the trajectory of the object can be tracked to determine if a vital organ or major blood vessel would be transected. Powerful bullets can shatter a skull, but careful reconstruction can usually reveal the entry and exit wounds. The presence of beveling at the edges of the wound gives important clues to the angle and direction of entry. Because bone is solid, measurement of the entry wound can indicate the caliber of bullet or size of buckshot. It is also important to analyze the fracture patterns. In cases where more than one bullet is present, the pattern can help designate the point of entry of the first and subsequent shots. Metallic traces deposited in a cut mark could indicate the use of a knife, ice pick, screwdriver, etc. Blunt trauma can leave its mark on bones in many ways, ranging from incomplete breaks and depressed skull fractures to clean breaks and crushed ribs. Even when perimortem trauma is obvious, it may not be possible to determine if a skull fracture, for example, resulted from a murderous blow to the head, an accidental fall, or followed collapse from a fatal heart attack, especially if months or years have elapsed.

The complexity of this discipline makes it imperative that the proper authorities call in a qualified, up-to-date specialist whenever badly decomposed, dismembered, or skeletonized remains are found. Moreover, an otherwise strong criminal case may be jeopardized if the credibility of the forensic anthropologist is challenged because of a deficiency in training or lack of familiarity with the most current literature and the advantages, liabilities, and limitations of it.

Acknowledgements:

The Police Department; 

https://www.politie.nl/mijnbuurt/politiebureaus/05/burgwallen.html and a Chief Inspector – Mr. Erik Akerboom                                 ©

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