Forensic Anthropology

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Diane L. France, Ph.D., D.A.B.F.A.

Director, Laboratory for Human Identification

Colorado State University

Contents

INTRODUCTION

WHAT DO FORENSIC ANTHROPOLOGISTS DO?

SEARCH AND RECOVERY

LABORATORY ANALYSIS

DETERMINATION OF SEX

DETERMINATION OF AGE AT DEATH

Bone GrowthPubic Symphyseal FaceRib PhasesOld AgeDental Attrition

DETERMINATION OF ANCESTRY/RACE

STATURE

FACIAL RECONSTRUCTION/APPROXIMATION

PHOTOGRAPHIC SUPERIMPOSITION

PATHOLOGY

Mechanical ForcesBlunt Force TraumaCut MarksGunshot WoundsHealing of BoneDisease ProcessResolution of the Case

CAREERS IN FORENSIC ANTHROPOLOGY

Acknowledgements

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Bibliography

This module will introduce you to the essentials of forensic anthropology, especially as practiced in the United States and Canada.Forensic physical anthropologists take the basic understanding of the human body, as provided by physical/biological anthropology,and add to it the principles of medico-legal investigations of identity and the circumstances of death.

Forensic physical anthropologists specialize in the research and application of techniques used to determine age at death, sex,population affinity, stature, abnormalities and/or pathology, and idiosyncrasies to (usually) modern skeletal material. Forensicscience is defined as the application of scientific methods to the law. Forensic physical anthropology is the application of varioustechniques of physical anthropology to legal questions. The term "forensic anthropology,” in a strict sense, can be used to describe anysituation in which the techniques of any aspect of anthropology are applied to the law. Archaeology, primatology, paleoanthropology,etc., can be called forensic anthropology if they are applied in this way. However, in this module (as in common professional usage),forensic anthropology will refer to the use of physical/skeletal biological methods only. In keeping with the holistic nature ofanthropology, forensic anthropology incorporates information and techniques from fields such as anatomy, physics, chemistry,pathology, law enforcement, and others. As in many other fields in science, the advancement of forensic anthropology developed as aneed to find improved methods in order to identify remains in law enforcement or in war.

The techniques used in forensic physical anthropology are often used in describing non-forensic cases — such as archaeologically-derived specimens — but that use, strictly speaking, is not forensic anthropology. In fact, it is this difference in application andcontext that distinguishes forensic anthropology from the other subdisciplines of physical anthropology. Moreover, forensicanthropologists know they must be prepared to defend any professional statements they make in court.

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The first contact a forensic anthropologist receives usually comes from law enforcement officials. Moreover, forensic anthropologistsdo not strictly work for the prosecution, and, likewise, they are not solely involved in criminal cases. Forensic anthropologistsfrequently work with the defense in criminal cases, and they assist in civil cases as well. Strictly speaking, forensic anthropologistsshould be willing to answer questions as they arise, regardless of from which side they originate. If, in a criminal case, the expertwitness — such as a forensic anthropologist — was to choose not to fully answer questions for either the prosecution or the defense,he or she has already determined the guilt or innocence of the defendant. In our judicial system, that right belongs to the jury orjudge, not to the person who has been asked to render an expert opinion about certain facts in that case. Forensic anthropologistswork for the victim, and, as long as they tell the truth, justice will be served.

Forensic anthropologists often work with coroners and medical examiners in the identification of individual skeletons in which theidentity of the remains cannot be established by other means (dental identification, fingerprints, or DNA, for instance). Thoseremains do not have to be skeletonized in order for skeletal clues to be useful, and frequently forensic anthropologists are called toassist with decomposed, burned, or fragmentary remains. As referenced in Box 1, forensic anthropologists are also called to assist inthe recovery and identification of remains from mass fatality incidents, including plane crashes, building explosions, and othercircumstances in which the remains are fragmentary and commingled (remains from one individual mixed with those of otherindividuals). The information from the skeleton can even be used to help establish whether two photographs likely represent thesame individual.

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Mass Fatality Incidents: The World Trade Center

Increasingly, forensic anthropologists are responding to massfatality incidents to help other experts in the identification of thedeceased and to help recover materials and evidence from thescene of the incident. We have responded to, among otherdisasters, airplane crashes, building explosions, cemetery floods,and the more recent terrorist attacks on New York City,Washington DC, and Pennsylvania.

In the early 1990s, a team of forensic specialists called DMORT(Disaster Mortuary Operational Response Team) was formed. Thisteam is supported by the United States government under the U.S.Public Health System. It consists of forensic pathologists, forensicodontologists (dental experts), forensic anthropologists,radiologists, fingerprint experts, security officers, funeral directors,computer specialists, photographers, and others, all working toestablish the identity of the victims and to investigate thecircumstances surrounding their deaths. Team members are onstandby 24 hours a day, seven days a week, prepared to respond tofederally declared mass fatality incidents on U.S. territory. We donot respond to all disasters but only to those which involve moredeceased individuals than can be processed by the local experts. Atthat point, the team members who are called to assist becometemporary federal employees for the duration of their response.

I am a long-term member of DMORT and have responded to manymass fatality incidents, including plane crashes and buildingexplosions. Although I have worked on many human identificationcases since I received my Ph.D. in 1983, nothing compares to amass fatality incident. We are required to work twelve to thirteenhours a day, seven days a week for two weeks. At that point, we arestrongly encouraged to leave the scene for at least a short time sothat we don't burn out. The work is intense. The emotions areintense. Many people ask what goes through my mind when Ireceive the call to respond, and the short answer really is“everything.” Sometimes you must arrive at your closest airportwithin hours, so some of what goes through a person's mind is of apractical nature. I have to prepare my home, my dog, my smallbusiness, and pack within those few hours. At the same time,though, my mind is becoming focused on the mission. What will berequired in setting up the temporary morgue? What will we have todo at the scene to recover the remains? When the plane is leavingthe runway, I always wonder how I will be a changed person whenI return.

When we arrive at the scene, the adrenalin level and the focus levelare both high. Frankly, I think that this is part of the appeal forresponders, as well as for firefighters and law enforcement officers,who are in the middle of intense situations. Unquestionably, it ishorrible to see this level of human tragedy, and we certainly see

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things that no person should ever have to see. But, an experiencedresponder will look beyond those things to search for clues whichwill identify the deceased. That is what I mean by focus. During thetime we are at the scene, almost nothing else in the world exists(even to the point of having to be reminded to drink plenty ofwater, eat, and to rest).

Also, it has long been recognized that people who share a commonintense experience often form a close bond that lasts forever. Manyof the people with whom I have responded to mass fatalityincidents are now like family to me.

When I hear of a plane crash or some other mass fatality incident, Iusually start to pack, thinking that I may be called to assist. OnSeptember 11, 2001, I initially could only stare at the television,stunned as the rest of the world was, when the second plane hit theWorld Trade Center. After about a half hour, I started to pack, but,because the airports were immediately closed, I was not able torespond to the disaster until late September.

For the duration of my stay, I was asked to work at the landfill onStaten Island. The situation was incredible. In fact, this is a termthat is used repeatedly by everyone describing the events and theresponse: “incredible.” The environment at the landfill was dirty,noisy, and dangerous. Materials were brought from “Ground Zero”to the landfill on barges and were stacked at the landfill waiting tobe processed. The large pieces of metal (primarily beams) werestacked at one end of the landfill to await transportation to therecycling centers. Everything else was sorted by large machines andby hand. At first, the materials were taken from the stacks — whichwere up to about 35 feet tall — by cranes to giant shakers andconveyor belts. These machines sorted the materials into differentsizes. The larger materials were taken from this process to therecycling areas or to permanent disposal, but the medium andsmaller materials were sorted by workers with rakes or literally byhand. We were looking for only two things: human remains andairplane parts, especially the “black boxes.” We wore hazmat suits,complete with heavy boots, masks, goggles, hardhats, gloves,earplugs, and tyvek coveralls. This protected us from most of theenvironmental hazards — not the sharp objects, of course — but itdidn’t isolate us from the heat, cold, and noise. It was like aJurassic ballet with all of the cranes working at once. When onecrane dipped its head, another lifted its cargo. The ground shookevery moment from the vehicles with tracks moving across thelandscape. Methane bubbled from the ground from the previouslandfill debris. The work continued around the clock.

And believe me, it was hard work. The lines of individuals whowere sorting this debris by rakes and by hand were primarily fromvarious law enforcement and investigative agencies. When I wasn’tin the crime scene trailer sorting human from nonhuman remains

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(nonhuman because there were many restaurants in the WTC area),I was among those sorting on the lines. I regularly work out in agym and am in pretty good physical shape, but I was soonexhausted. All of the sorted organic materials were sent to the NewYork Medical Examiner’s office, where materials were logged andidentification techniques were initiated.

But the truth is that no one works independently at a mass fatalityincident, and that is even more true in a situation as horrific andmassive as those events that occurred on September 11. Manyresponders have written of their personal experiences on that day— from the mountain climbers who descended into the jaggeddepths of the debris to the chefs from across the country whovolunteered to cook for the workers. I worked with the New YorkPolice Department detectives who were reassigned from theirregular shifts or who, in some cases, worked their regular shiftsand then reported for extra duty. Most of these detectives hadwatched as the Twin Towers were built, and now they had to siftthrough the debris. I would work with them again in a heartbeat.Everyone from DMORT was able to go home to a regular routineafter staying for two weeks or a little longer. These folks had to stayfor the duration and will still be there years from now. All of usresponded in different ways to the national tragedy. However, forthe local emergency responders, this tragedy happened in theirhome.

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How do forensic anthropologists work with other experts in the investigation of the kinds of cases described above? Involvementvaries, depending on the nature of the case, but often the first step is to help in the location and recovery of bodies from surfacedeposits or from “clandestine” (secret and, usually, with criminal intent) graves. This, by the way, is a relatively new aspect offorensic anthropological work, in that previously most forensic anthropologists only performed laboratory analysis. It makes sense,however, that the context in which a body is discovered can be important to the evaluation of the remains, including marks on thebones, the amount of time that has elapsed since death, etc. For example, if a body with blunt force trauma to the legs is brought tothe laboratory, the diagnosis of the mode of trauma might be different if the body was discovered near a highway, under a cliff, or inthe middle of a flat field. In another situation, the analysis of a crime and the presentation of evidence in court might be different ifthe victim’s left arm was missing because the grave was disturbed by scavengers as contrasted to a grave undisturbed at the time ofdiscovery.

In the search for a clandestine grave, forensic anthropologists should be part of a team of experts who look for changes in thesurrounding environment that tell them the area has been disturbed. This team is always under the direction of the law enforcementagency in charge of the case, so that the inquiry is not compromised by well-meaning, but uninformed, volunteers arriving at a sceneto help.

Naturally, a disturbance in the environment does not necessarily mean that a grave has been discovered. So, what are some of theclues to look for in finding a clandestine grave? When someone digs a hole, the site is changed in predictable ways, depending onenvironmental circumstances. For instance, the changes to a grave over time in very wet environments will be different than those invery dry environments. In any environment, plants within the hole are destroyed as the root system is compromised. Plants under the

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dirt thrown from the hole will be damaged, but they will usually recover relatively quickly from the insult. If the ground hadpreviously been completely undisturbed, the layers of dirt are predictable, in that the more organic layers (those formed by thedecomposition of plant materials) are close to the surface, while the rockier layers are deeper. When the dirt is removed, those layersare mixed, so that when the dirt is placed back into the hole, the layers no longer exist. In addition, often the lighter layers (lessorganically rich) will show on the surface. The ground is often mounded if the perpetrator wants to return all of the dirt back to thehole, and it will become quickly depressed after precipitation compacts the soil within the grave, particularly if the perpetrator left thesurface flat. So, for starters, one would look for damaged plants or bare ground and either mounded or depressed ground with thelayers mixed — which is determined when a small test trench is dug into the suspected grave.

If a significant period of time elapses between the time of burial and the time of the search, plants will begin to colonize thedisturbed area. Again, environmental circumstances have an influence here. For instance, the plants in a wet environment maycolonize the grave within a season while a grave in an arid environment may remain relatively bare for years. Even smallerenvironmental differences, such as the seasons of the year or whether the grave is on a north slope or a south slope, will influence thecolonization rate. Often the plants that initially invade the disturbed area are the same plants that invade other disturbed areas in thevicinity — such as road cuts or overgrazed areas — and frequently they will be different species from those in surrounding,undisturbed areas. These new, colonizing plants can include many species — such as thistle, cheat grass, and kudzu — that are able toroot quickly because the soil in the grave has recently been aerated.

Because the soil in the grave is aerated, it is less dense than in the surrounding area. Therefore, methods such as ground penetratingradar, infrared detection, and electromagnetic techniques may be of some help in finding an area after the surface indicators arefading. Even though years may have passed since a body was buried, the soil within a grave can remain less dense and can havedifferent conductivity values than the surrounding soil.

Additional search techniques may be used as well, depending on environmental situations and on the experts who are available in thearea. For instance, highly trained detection dogs may be used to assist in locating remains. However, the standard pedestrian searchis the technique most often used. Searchers, who are experienced in recognizing the clues, walk an area in a straight line in a way thatthe area searched by their eyes overlaps the area searched by the individuals walking next to them. If one person sees a clue, theentire line stops until that area is flagged for further investigation or until the item or area is determined to be insignificant.

Obviously, great care must be used in recovering remains from a grave. Exhuming the body destroys the context within the grave, soone must be proficient in recording all of the bits of evidence, including the precise locations of evidence. All of this seems obvious,but there are countless examples of law enforcement agents, and even archaeologists and physical anthropologists, moving tooquickly through a grave exhumation and missing important contextual information.

Modified archaeological techniques are often used to accomplish this task. Archaeologists usually establish a grid system over an areato be excavated and often over an area where remains were scattered on the surface. The excavation takes place within each grid(usually 1 meter square), and all of the dirt removed from each level within the grid is screened. In this way, even if the archaeologistsmiss an item in situ (in its original location), at least some locational information will be recovered as it is screened. As each item isuncovered, it is given a number, its location is mapped (using vertical and horizontal coordinates), and it is photographed.

Who picks up and records the evidence at a scene? Technically, anyone can do this, as long as proper chain of custodyrequirements are met. The chain of custody is fulfilled with a series of documents which record who had control of material, when itwas received, when it was released to another individual, and what was done to the material at each step. This documentation isimportant so that each side in a court case knows exactly how the evidence was processed, by whom, for what reasons, and how thevarious procedures may or may not contribute to solving the crime. Often the anthropologist will help locate and uncover theevidence at the scene and let the law enforcement crime scene technician actually recover the evidence to reduce the number of linksin that chain. The anthropologist is not removed from the chain by doing this — his or her involvement is recorded in the crime scenelogs. Also, if, for instance, a specific test is performed on a piece of evidence, that test must be documented. In fact, everything mustbe documented. If, for example, a forensic anthropologist is to study a set of remains and if a bone is nicked with a scalpel duringautopsy, that damage must be documented by the forensic pathologist so that the anthropologist will not mistake it for damagepotentially caused at or about the time of death.

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Case A

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A man's decomposed body was discovered in a rural area. Thesheriff's officers, who responded to the scene, suspected that theindividual was the victim of homicide because of the obviousdamage to the clothing and to the body underneath. It appearedthat the shirt had numerous cuts. The body was transported to thelocal medical examiner's office for an autopsy, while the area thatwas around and under the body was searched for evidence.

The forensic anthropologist was called to the medical examiner's office so that she could attend and then participate in the autopsy.Forensic anthropologists work as a team with the forensic pathologist, forensic odontologists, forensic radiologists, and all otherforensic experts. In this case, the forensic pathologist performed the autopsy, which was somewhat modified because of the extensivedecomposition of the body. Because the evidence that forensic anthropologists need is usually obtained from the skeleton, their workusually starts after the pathologist is finished. The soft tissue is usually removed from the skeleton so that the clues are more obvious.

In every step of the way through the search and recovery and also throughout the laboratory analysis, the forensic anthropologist isaware of, and is working toward, fulfilling an incredible set of responsibilities. This was once a living person, and there are very fewprofessionals who are trained to tell his or her story. It is important to provide information so that the family members of the victimcan have the answers they seek concerning the circumstances surrounding the death of that individual. It is equally important thatthe anthropologist be prepared to go to court with the findings.

The investigation of the identity of human remains must begin with a determination of whether or not the remains are human. If theremains are not human, the case usually ends, although the author has been asked to continue on cases in which, for instance, a doghad been shot. In this case, the shooter claimed that the dog was attacking him. The direction of travel of the bullet was important inthis case, as the dog was not facing the man when he was shot.

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After the remains in question are determined to be human, the next question is usually sex determination, as this eliminatesapproximately 50% of the reported missing individuals from further consideration. Because skeletal differences between males andfemales are not fully established until puberty, sex determination is very difficult and unreliable in very young individuals.Consequently, the techniques used to establish sex are approximately 60% to 70% accurate in very young individuals. After puberty, males are usually bigger than females. The bones are larger overall and the areas devoted to muscle attachment arelarger and more rugged, just as in other primate species — for example, gorillas and orangutans — and in many other mammals. Thisdifference is what has been defined in the textbook as sexual dimorphism. However, in order to utilize this size difference in sexdetermination, the researcher must be able to identify the population from which a skeleton came, as populations differ greatly inaverage skeletal size and degree of sexual dimorphism and proportions. For example, populations native to India usually have smallerskeletons and exhibit less sexual dimorphism than Australian Aborigines. An adult male Asian Indian skeleton placed alongside amale (or many females) adult Australian Aborigine skeleton would, if judged on the basis of size, be misclassified as a female. A studyperformed on humeri of Arikara vs. Pueblo (North American Native groups) misclassified almost 70% of the male Pueblo humeri onthe basis of size alone. This indicates that size differences between these two populations could easily confuse sex differences (France,1983). For this reason, morphological differences are usually more reliable than are general size differences, particularly if one is notsure from what population an individual is derived. Another complication can arise from cultural practices, since variability in muscle use can also reduce the reliability of skeletalindications of sex. For instance, a female who lifts heavy weights will have upper arm measurements that are closer to her malecounterpart, particularly if he sits behind a desk and does no heavy lifting. Likewise, in a culture in which burden baskets are carriedon the female heads, the size of the mastoid process of the cranium will increase so that a population would show less dimorphismfor that trait.

The most reliable skeletal area for the determination of sex is, as one might guess, the pelvic girdle. As is easily remembered, the sexdifferences are greatest in this area because the female pelvis is shaped differently to accommodate the needs of childbearing. Severalareas of the pelvic girdle show these differences (see Figures 1a and 1b).

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Figure 1a Female pelvic girdle

Figure 1b Male pelvic girdle

It has been widely taught that the second best area for sex determination is the cranium (see Figure 2). Measurements of thepostcranium, while important, should be the basis for sex estimation only when the cranium and pelvic girdle are not usable. Whenthe entire skeleton is available for inspection, the other areas of the skeleton should not be ignored, even though the pelvis is present.Always remember, the more information gathered, the better. In fact, if one knows the population from which a skeleton is derived,postcranial measurements can be highly reliable. Some researchers report an accuracy rate of over 90% in some measurements (cf.Krogman and Iscan, 1986; Dittrick and Suchey, 1986; France, 1983) (see Table 1). For a more thorough discussion of some of thetechniques being studied, consult Krogman and Iscan (1986).

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Figure 2 Male (left) and female (right) skulls

Table 1 Table of some metric determinants of sex

Maximum Head Diameter of Femur (in mm.)

Population Sex N Mean S.D.Cutoff

CorrectlyClassified

African Americans(Tennessee DataBank) M 70 48.0 >=46.0 84%

F 40 42.4 <=45.0 90%European Americans (TennesseeData Bank) M 150 49.0 >=46.0 92%

F 100 42.4 <=45.0 93%Native Americans (CentralCalifornia Combined Horizons) M 175 47.0 >44.6 88.7%

F 171 42.2 <44.6 Central California Combined Horizons (Early Horizon, beginning circa 2500 B.C. through Late Horizonbeginning after 500 A.D. from Dittrick and Suchey, 1986).

Maximum Head Diameter of Humerus (in mm.)

Population Sex N Mean S.D.Cutoff

CorrectlyClassified

African Americans(TennesseeData Bank) M 70 47.4 >=45.0 86%

F 40 40.8 <=44.0 91%European Americans (TennesseeData Bank) M 150 49.0 >=46.0 89%

F 160 42.3 <=45.0 93%

Vertical Head Diameter (in mm.)Population Sex N Mean S.D. Cutoff Correctly ClassifiedNative Americans Pecos Pueblo M 86 43.4 >=41.0 91.6%

F 69 37.9 <=40.0

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Native Americans Arikara M 93 46.7 >=44.0 90.5

F 86 41.2 <=43.0 From France, 1983

From these photographs, what is the sex of the individual in Case A (see Figures 3, 4, and 5)?(The answers to this question, and other questions will be revealed at the end of the module in the resolution.)

Figure 3 Left pubis from Case A

Figure 4 Right greater sciatic notch from Case A

Figure 5 Cranium from Case A

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Several methods are commonly employed in the determination of the physiological age of a skeleton. Researchers hope that thephysiological age will give an accurate estimate of chronological age, but environmental, nutritional, and disease stresses will oftencause changes in the skeleton which will mask the true age of the individual. Dental formation and eruption times are less affected byinsults, such as disease and nutritional deficiencies, than are the formation and maturation of the bony skeleton. Therefore, whereappropriate, these dental criteria are more reliable age determination techniques. Because of variation in disease and nutritionaleffects, the diagnosis of age in a skeleton will always be represented as a range, as the physiological age can span severalchronological years.

The most appropriate specific age determination technique applied to a skeleton depends on the general age category of the skeleton.If the individual is relatively young, dental formation and eruption times are the most accurate means of identification. Thedetermination of the ages in which the deciduous and permanent dentition erupts is useful in identifying age to approximately 15years (see Figure 6). The third molar (wisdom tooth) erupts after this time, but the age of eruption is so variable that it is, by itself,not a very reliable age indicator. There is also the possibility that the tooth may never erupt.

Figure 6 Dental age determination chart (courtesy Douglas Ubelaker)

Even though bone growth occurs concurrently with dental development and eruption, it is not as reliable as an age indicator. Ofcourse, there are times when no dental evidence is available, so it is important to know about bone growth.

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Bone Growth

Postcranial bones, except for the clavicle, are formed initially in cartilage — that is, a cartilage model precedes actual formation ofbone. In addition, several bones of the cranium are formed from cartilage models. Depending on the bone in the body and atdifferent times during growth, osteoblasts (bone-forming cells) invade the cartilage to lay down bone. The ossification centers arethe points at which this initially occurs in each bone. The diaphyses (singular = diaphysis) (primary centers of growth) areresponsible for most of the length of long bones. The epiphyses (singular = epiphysis) (secondary centers) are separated from thediaphyses by metaphyses (singular = metaphysis), which are thin layers of cartilage being sequentially overtaken and replaced bybone. The metaphysis is the actual site of bone growth. When the diaphysis meets the epiphysis, the metaphysis disappears, the endsof the bones fuse, and the longitudinal growth ceases. Because this epiphyseal closure occurs at different times in different bones, the

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age of an individual can be determined by which epiphyses have fused and which have not. Figures 7 and 8 show an epiphysis anddiaphysis which have not yet fused. Notice the characteristic undulating appearance of the unfused surfaces of bone.

In evaluating a fully adult skeleton in which the teeth are erupted and all epiphyses are united, it is necessary to look atdevelopmental and degenerative changes in other parts of the skeleton. At one time the ages at which the cranial sutures (theareas separating the bones of the cranium where growth occurs) become obliterated was used quite extensively. However, with moreresearch, the ages of suture closure were found to vary widely, making this technique unreliable in the precise determination of age.In addition, endocranial sutures (the sutures as seen inside the cranium) are often difficult to see and interpret in intact crania.

However, a review of a sample of crania from people (144 males and 51 females) of various ancestries from the Los Angeles Coroner'sOffice (Baker, 1984) indicates the following general guidelines:

Endocranially:

1. If all sutures are completely open, the individual is less than 36 and usually less than 27.2. If all sutures are completely closed, the individual is 26 or older.

Figure 7 Epiphyseal surfaces from left femur and its distal epiphysis

Figure 8 Distal epiphysis from femur in proper position

Pubic Symphyseal Face

The pubic symphyseal face (where the two pubic bones are joined through cartilage in the front of the pelvic girdle) in a youngindividual is characterized by an undulating surface, such as seen on a normal epiphysis. But it undergoes relatively regular changesfrom age 18 onwards. Several researchers have developed age determination techniques based on the changing morphology of thesymphyseal face. Earlier systems (Todd, 1920; McKern and Stewart, 1957) have been largely replaced by a system using a moremodern, representative sample (the Suchey-Brooks system). This is a six-phase system based on a large sample of individuals forwhom legal documentation of age is provided by death certificates. This autopsy room sample, comprised mostly of individuals bornin the United States and Mexico, is more representative of the general population than was true of previously used samples.

Figures 9a and 9b show the key features distinguishing the pubic symphysis phases in both males and females. Note from thephotographs that, at very young ages, the surface of the pubic symphysis somewhat resembles a young epiphyseal surface. As theindividual ages, this surface and the surrounding aspects of the bone proceed through regular changes until at old age it presents amore porous bone, sometimes with spicules of bone growing away from the surface. The pubic symphysis of both females and malesgo through similar phases, but the exact nature of these changes can be altered in several ways (see Table 2).

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Figure 9a Male pubic bone age determination (courtesy Judy M. Suchey)

Figure 9b Female pubic bone age determination (courtesy Judy M. Suchey)

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Table 2 Descriptive statistics related to the Suchey-Brooks pubic age determination system

Female Male

Phase mean S.D. 95%range mean S.D.

95% range

I 19.4 2.6 < 24 18.5 2.1 < 23II 25.0 4.9 19-40 23.4 3.6 19-34III 30.7 8.1 21-53 28.7 6.5 21-46IV 38.2 10.9 26-70 35.2 9.4 23-57V 48.1 14.6 25-83 45.6 10.4 27-66VI 60.0 12.4 > 42 61.2 12.2 > 34

These are intended to be brief introductions of this system. For the complete information on the system, please consult Suchey and Katz, 1998.

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Rib Phases

The changes experienced by the rib are similar in some ways to those changes in the pubic symphysis. Iscan, et al. (1984, 1985) haveselected and illustrated specific phases for age-related changes in the sternal end (anterior, near the sternum) of the fourth rightrib. In the earliest phases, the surface which articulates with the sternum is flat or billowy with a regular rim and rounded edges. Thebone itself has a young appearance. As the individual ages, the center of the face is indented relative to the edges, and thisindentation increases throughout the life of the individual. The rim become less regular in shape, and spicules of bone project fromthe edges. The bone becomes more porous and brittle as the individual becomes older.

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Old Age

Basically, the developmental changes which characterize young skeletons give way to the degenerative changes of old age. Arthritis(see the changes in Figure 10) becomes more prevalent and pronounced, as does osteoporosis (increased porosity of the bone,particularly in post-menopausal women). These changes can give corroborative evidence to determinations of older age, but are notreliable by themselves, as injury and disease can lead to many of these changes in the skeleton.

Figure 10 Degenerative joint changes in tibia at knee

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Dental Attrition

The amount of attrition on teeth has been traditionally used to determine the relative age of individuals within a population. It shouldbe stressed, however, that humans eat a variety of foods which promote enamel attrition at different rates. Consequently, dentalattrition should not be used to determine the absolute age of an individual, particularly when the dietary and other uses of the teeth

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in that individual are not known.

What is the age range of this individual in Case A (see Figure 11)? Notice that a range is requested. It is inappropriate and impossibleto give a specific age in these cases because of the range of human variation, in addition to nutritional and health differences betweenindividuals of the same age.

Figure 11 Pubic symphysis from Case A

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A controversy in anthropology exists today over whether or not "races" exist. For centuries peoples in the world have beencategorized into groups, the most recent titles being Caucasoid, Negroid, Mongoloid, and usually Australoid and Polynesian. (See textfor further discussion.)

There are many reasons to discontinue the use of racial terminology for humans. The terms used — as well as the identification ofdifferences between groups in general — have made it easier in history for groups of people to attempt to demonstrate that they aremore intelligent, more fit physically, and more deserving of the benefits of society than those individuals who are different. Racismhas used these terms as its tools.

Racial terms place people in pigeonholes even when they do not physically fit. It is generally recognized, and often stated, that thereis more variation within races as they are usually defined than between racial groups. There is a continuum in each of the traditionalpolygenic characteristics — such as skin color, hair form, etc. — which makes it impossible to categorize every individual in the worldinto rigidly defined racial groups. Thus, it is more accurate to investigate traits as clines instead of absolute defining characteristics.(See text.)

Forensic physical anthropologists, however, would be derelict in their duty if they ignored the morphological differences which canhelp to identify an individual. When an anthropologist is asked to assist in the identification of a parcel of bones, part of thatidentification must include a statement as to probable ancestry or "race," because this feature is included in the social identity of thatperson. This identity was traditionally made in racial terms and was usually made by the person him- or herself. This identification ofancestry, however, is changing, in that more of the world's inhabitants are identifying themselves according to the geographic orpolitical location of their ancestors — i.e., German or Spanish or Bosnian instead of Caucasian or even European. The question forforensic physical anthropologists then becomes, How closely can we estimate these more refined identities from the physicalremains? The answer is, It depends. If a person identifies himself as an African American, it implies that his recent ancestors werefrom Africa but that he is currently living in America. The forensic anthropologist, of course, cannot determine the person's currentplace of residence by the bones alone, so perhaps we would be misleading the law enforcement official if we say that this is an"African American." However, it is becoming more feasible to determine, with experience, the probable ancestral background withmore refinement, even to the point that many forensic anthropologists can determine the regional ancestry of many Native Americangroups by looking primarily at the facial morphology. Many forensic physical anthropologists are now stating in their reports that, forinstance, the remains are from an individual with European ancestry, or with African ancestry, or even with western African ancestry.

One thing must be stated, however. Even as forensic physical anthropologists are becoming more skilled in their abilities to detectclues about ancestry in the skeletal morphology, it is important to realize that no matter what terms are used to describe the

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individuals we study, those terms, also, will initiate objections if they are misused. If any term is used maliciously or with intent tocreate a political hierarchy between recognized groups, its use will increase suspicion and ill will between peoples. Reputable forensicphysical anthropologists want the terms they use to be clues to the eventual identification of remains and nothing more.

In the final analysis, students must decide not only the appropriateness of the terms used, but also whether or not it is legitimate anduseful to have a group of scientists endeavor to determine the identity of unidentified human remains and to allow them (and you) todevelop better methods of determining ancestry. Without that tool, forensic physical anthropologists are less well equipped to help inthat identification process.

Figure 12 European American cranial features (courtesy J. S. Rhine)

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Figure 13 African American cranial features (courtesy J. S. Rhine)

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Figure 14 Native American cranial features (courtesy J. S. Rhine)

What is the probable ancestral background of the individual in Case A (see Figure 15)?

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Figure 15 Cranium from Case A

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Estimates of living stature from the skeleton are a routine part of the analysis of remains, but they are not very precise. Therefore,they should never be used alone in establishing identity. An example in which stature reconstruction becomes more important is insorting of commingled remains — that is, remains of several people where it is more difficult to sort the remains into individualsagain. In a simple situation with two individuals, one tall and one short, it is a relatively simple matter to sort the remains by stature.

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The ability to apply a face to a skull is dependent on the ability to predict the thickness of soft tissue on the face. In early studies thethickness of the soft tissue of many individuals was measured as soon as possible after the person had died by inserting a pin intostandard locations and measuring that thickness directly. Today tissue thickness is measured using ultrasound on living individuals.Not only is this technique an improvement esthetically, but more importantly it is an improvement as the soft tissue has not had achance to lose its tone.

Facial approximation is typically used only after other methods for identification have not yielded results. A face is applied to theskull either in clay or with two dimensional drawings or computer renderings. That rendering is placed in newspapers and ontelevision in the hope that it will trigger someone to call law enforcement and say something like "That resembles Uncle Joe whodisappeared two years ago." At that point, the antemortem (before death) medical and dental records, and perhaps DNA samples,for Uncle Joe are obtained, and experts decide if these are the remains of Uncle Joe.

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Occasionally a skull is compared photographically to antemortem photographs of the suspected victim. Usually the photograph of theperson is videotaped with one camera while the skull is videotaped with another video camera, and the two video feeds are digitallymixed to perform the superimposition. Of course, it is important that the skull be in the same plane as the photograph, otherwise,even if it is a positive match, the superimposition will not match. This technique should not indiscriminately be used as a means ofpositive identification. Even with the best equipment and the best results, there is still about a 10% chance that with one view therewill be a positive match even when the two images are not from the same individual.

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Many mechanical forces and disease processes leave their marks on bone. Large volumes are dedicated to the study of theseconditions, but we will view only a few of them here. It is important to note, though, that while forensic anthropologists can describeand diagnose many of these forces and disease processes, they cannot (by law) determine cause or manner of death. This is theresponsibility of the coroner or medical examiner.

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Mechanical Forces

Many types of mechanical insults — such as, cut marks and sharp force injuries, blunt force trauma, gunshot wounds, and others —are seen by forensic physical anthropologists, pathologists, archaeologists, and medical examiners. Obviously, some injuries arecombinations of two or more of these categories. For instance, sharp force injuries — such as saber cuts or hatchet cuts — include thecutting action of the sharp end of the implement and, also, the impact forces released as the weapon strikes the bone. Victims ofplane crashes or building explosions sometimes exhibit many different types of forces.

Bone is elastic in life and can "bounce back" from many mechanical forces, particularly if the force is slow to build and contains littlepower. However, if a great deal of force is quickly applied, bone will fracture before it has a chance to exhibit its elastic qualities.Slow-loading or slower-impact forces produce more elastic response from bone before it fractures. Fracture lines usually radiateaway from the point of initial impact, hence, they are called "radiating fracture lines." Radiating fracture lines from multiple injuriesusually do not cross each other, but they stop at other fractures or cranial sutures. Depending upon the degree of force and the areain bone, concentric rings may also radiate away from the point of initial injury (likened to dropping a pebble in a pond). They are alsohelpful in identifying the initial point of contact with bone. In contrast, trauma to dry bone usually results in fractures with raggededges and without the radiating fracture lines or concentric rings. Thus, these fracture patterns are also crucial in distinguishing freshbone injuries from dry bone damage.

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Blunt Force Trauma

Blunt force trauma is as its name implies, damage caused to bone by objects with relatively broad surfaces as opposed to a sharpinstrument. This type of injury usually results from a relatively slow-loading force and can cause significant plastic deformation of thebone before the bone fractures. Blunt force trauma often results in the separation of wedge-shaped fragments of bone, as bone canwithstand compression forces to a greater degree than it can withstand tensile forces (those which pull bone apart) (see Figure 16for example). See Figure 17 for an example of blunt force trauma in the human occipital bone.

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Figure 16 Diagram of forces in bone

Figure 17 Blunt force trauma in cranium

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Cut Marks

Cut marks are caused when a sharp object incises bone. Upon close inspection with a dissection microscope or scanning electronmicroscope, cut marks typically have a "V" shape or a series of "V" shapes — such as made by stone tools which have a series ofparallel cutting edges along the worked edges (see Figure 18). Vascular grooves (channels in bone through which blood vesselspass, most often the grooves along the lateral aspects of the frontal bone) are often mistaken for cut marks, but they have a roundedor "U" shape in cross section. Rodent tooth marks can also be mistaken for cut marks, but typically they are paired and have a squarecross section (see Figure 19). Sharp force injuries that combine cut marks with force often leave a "V" cross section with compactedbone near the center of the cut that is frequently lifted and has somewhat displaced edges.

Figure 18 Scanning electron micrograph of cuts made from stone tool. Notice parallel striations

Figure 19 Rodent tooth marks on bone

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Gunshot Wounds

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Gunshot wounds are produced by bullets of different size (caliber) and are projected by a wide range of explosive force. They aresomewhat predictable in that the missile usually creates a round opening, depending on the degree of wobble and tumble in thebullet. This is smaller at the initial point of impact of the bullet to the bone and larger at the point of exit from bone. In this way thedirection of travel can often, but not always, be determined by looking at the direction of beveling in the bone (see Figures 20 and21).

Figure 20 Gunshot entrance wound

Figure 21 Gunshot exit wound

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Healing of Bone

How does one determine whether or not an individual has survived a mechanical insult to bone? In all of the above examples, theedges left by the insult are sharp. Bone reacts to fractures by immediately forming a callous around the point of fracture. This callousis initially soft tissue but is replaced quickly by deposits of bone, which are thereafter remodeled into sturdy new bone. The process offormation of loosely woven bone stabilizes the fracture within weeks, depending upon the age and health status of the individual. Theremodeling process continues until all woven bone is replaced by dense bone tissue. If the bone is properly set, it should be nearlyidentical to its condition prior to fracture. In cases where fractures are not properly treated, there can be considerable deformity (seeFigures 22 and 23).

Figure 22 Healed displaced fracture of tibia

Figure 23 Healed displaced fracture of tibia, longitudinal cut view(courtesy Armed Forces Institute of Pathology, National Museum of Health and Medicine)

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Disease Process

It is often very difficult to diagnose the specific pathogen responsible for disease changes to bone, as bone can react to the entiredisease spectrum in limited ways — i.e., the addition of new bone and/or the destruction of existing bone. Because evidence ofdisease and/or trauma can greatly assist in the identification process by comparisons with medical records, experiencedanthropologists and pathologists will describe the changes seen in the entire skeleton. Remember that it is more important toaccurately describe the bony changes you see than to diagnose the specific pathogen responsible for those changes. As we learn moreabout disease processes in bone, the diagnosis may change, but the description most likely will not.

Describe the damage to the body in Case A. In your opinion, what could have caused the damage shown in each photograph? Notethat there may be different "tools" used in each case. (Use Figures 24 through 29 for your analysis.)

Figure 24 Cranium from Case A

Figure 25 Ribs from Case A

Figure 26 Pelvic girdle from Case A

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Figure 27 Occipital bone from Case A

Figure 28 X-ray of cranium from Case A. Notice spot of radiopaque substance at arrow

Figure 29 X-ray of ribs from Case A

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Resolution of the Case

Case A: According to the evidence and to eyewitness reports, this individual, who was a 45 year old male of European ancestry, wasattacked and robbed by several teenagers. They later confessed to stabbing him multiple times with a knife, and then, after he hadfallen, shooting him in the chest. As they were driving away, they ran over the victim twice with a car.

As can be seen, however, one part of their story is not supported by the evidence. There is no evidence of a gunshot wound in thechest by the gross morphology of the bones of the chest — i.e., there are no round holes with beveled edges. In addition, as the bulletpasses through bone, it often leaves metal "smears" on the bone which can be seen by x-ray. There are no metal "smears" on thebones of the chest in this victim.

However, a gunshot wound can be seen on the left frontal bone. This is a classic "keyhole" fracture in which the bullet enters the bonetangentially, and, because the skull is rounded, exits the skull close to the entry. The combined hole then has beveled edges on boththe inside and the outside of the bone!

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Because of the angle of this wound, it is logical to assume that part of their story is true. The victim probably was already on theground when shot. According to the story, although the shooter was aiming for the chest, the bullet went off its mark and struck thehead.

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With the continuing popularity of forensic programs on television and in thepopular press, more students want to pursue careers in forensic physicalanthropology. Moreover, by taking an introductory physical anthropology classor a more advanced course, some students are stimulated to begin thinkingseriously about pursuing a career in this field.

There is an array of career possibilities within the forensic sciences as broadlydefined. Some of these career paths can be effectively pursued with abachelor’s degree, while other more specialized careers (discussed below)require more advanced training. For example, students who have begun withan undergraduate forensic anthropology orientation have gone on to careers asregular police officers or as detectives. Others have obtained positions asautopsy technicians in coroner’s offices, and several have pursued relatedcareers in biomedicine as physician’s assistants or as medical doctors — manyof these needing advanced degrees.

Numerous opportunities as a forensic specialist exist in crime laboratories.Usually this requires considerable academic course work and significanttraining in chemistry — i.e., at least the equivalent of a bachelor’s degree and,ideally, a master’s degree in chemistry.

A full-time professional position is the most romanticized career pathassociated with forensic physical anthropology. This would be an expert whoworks closely with law enforcement personnel and testifies routinely in court.Such positions, however, are extremely scarce and, understandably, requiremuch advanced training as well as demonstration of competence.

Forensic physical anthropologists, who wish to be professionally established atthe highest level, must become certified as an expert by the American Board ofForensic Anthropology. In order to gain such board certification, one must firsthave a doctoral degree in physical anthropology, be working in the field forthree years, and be invited to sit for an eight hour examination (both writtenand practicum). Presently, not all individuals who identify themselves asforensic anthropological experts are board certified; although almost all haveat least a master’s degree and several years of experience. Moreover, the vastmajority of practicing experts never obtain full-time positions. Most forensicanthropologists consult part-time while simultaneously pursuing parallelcareers, usually as university professors.

Finally, most experts — whether board certified or not — are members of the

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physical anthropology section of the American Academy of Forensic Sciences.This professional organization also has sections in engineering, jurisprudence(law), psychiatry, pathology/biology, odontology, criminalistics, questioneddocuments, and toxicology. There is also a general section for those expertswho are not members in any of the above mentioned fields. In order to be amember of the physical anthropology section, one must have at least amaster’s degree or must be working toward a graduate degree. For moreinformation about this organization, contact:

The American Academy of Forensic Sciences410 North 21st StreetSuite 203Colorado Springs, Colorado 80901-0669

Currently, only a few universities offer doctoral programs with an emphasis inforensic anthropology. Most practicing forensic anthropologists hold doctoraldegrees in physical anthropology with concentrations in osteology. They thengain experience in forensics with someone who is working in the field. Also,classes in anatomy, physiology, and physics are useful in calculating how bonereacts to different forces. For more information about the colleges anduniversities offering graduate degrees in physical anthropology, go to thereference section in your library or access specific university programs on theInternet.

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Acknowledgements

Lynn Kilgore and Robert Jurmain offered helpful editorial suggestions, and Judy Suchey gave helpful recommendations about pubicage determination. Most of the techniques that describe how to locate clandestine graves relate to work done by NecroSearch, International. You canlearn more about this group by visiting the web site: www.necrosearch.org.

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tents]