Forensic Anthropology: What Bones Can Tell Us

Transcription

1 CE U P D A T E F O R E N S I C S II John K. Lundy, PhD, DABFA Forensic Anthropology: What Bones Can Tell Us The discovery of skeletal remains prompts immediate questions: Are they human? If so, was the person male or female? What population was he or she from? How old was the person at death? How tall was the person? How long has the person been dead? What was the most probable cause of death? Forensic pathologists, coroners, and police officers usually are not properly trained to recover and analyze skeletal remains. The forensic anthropologist is best suited to recover and examine these remains and provide answers to these questions. Recovery Because forensic anthropologists are familiar with the human skeleton, their assistance is invaluable in the recovery of skeletal remains. The most common situation where skeletal remains are found is the surface scatter, which occurs when a body is dumped on the ground and the remains are scattered by animals over a wide area. The forensic anthropologist can determine at the scene which remains are nonhuman and which are human, saving investigators' time. If the remains are buried, archaeological methods are used to ensure that the amount and quality of remains recovered are of the highest standard (Fig l). 1 ' 2 Analysis After the remains have been recovered in the field, they usually are transported to a medical examiner's office or other laboratory facility for examination.3,4 The remains are described as found, and if necessary, cleaned and prepared before examination. For each set of human remains, forensic anthropologists attempt to provide a general physical description of the following factors: ABSTRACT The discovery of skeletal remains poses numerous questions that are best answered by those trained in forensic anthropology. Forensic anthropologists not only are able to determine at the site whether skeletal remains are human, but they also employ various methods to determine the gender, age at death, race, and height of the deceased. With advances in DNA techniques, forensic anthropologists will soon be able to derive information from older and older skeletal remains. This is the second in a three-part continuing education series on forensics. At the end of the series, the reader will be able to describe the traditional as well as new molecular pathology techniques used in detecting sexual assault; describe techniques used to recover, examine, and identify skeletal remains; and describe DNA techniques used in the forensic pathology laboratory. Gender Age at death.race.height o They also try to determine whether the bones provide evidence of the cause of death, to identify any individualistic features in the skeleton, and to estimate the time since death. Determining Sex The human pelvis provides the most reliable means for determining the sex of skeletal remains. The female pelvis is designed to offer optimal space for the birth canal, which is reflected in its morphology and the relationship of its parts to each other. Although measurements may be taken to determine the gender of the remains, an experienced anthropologist often can tell simply by visual inspection.5 The skull also can be used to determine the sex of an individual. From the Anthropology Department, Clark College, Vancouver, Wash, and the Medical Examiner Division, Oregon Department of State Police, Portland, Ore. Reprint requests to Dr Lundy, Clark College, 18 E McLoughlin Blvd, Vancouver, WA 98663; or jlundy@clark.edu 423 e 3 s O c I n

2 Fig 1. Students excavating a buried skeleton to learn forensic exhumation techniques. the degree of fusion of the first and second sacral bodies (S1-S2) to be useful, and the medial clavicular epiphysis in the early twenties.9 In later adulthood, one can use changes in the pubic symphysis as an indicator of age at death. A series of casts is available to compare with the unknown symphysis to estimate age.1 In older adults, we see degenerative changes in the spine and joints associated with the aging process. Other methods include microscopic aging of bone tissue11 and age-related changes to the ventral ribs.12 Race As the female progresses from puberty to adulthood, her skull retains many of the prepubertal traits, such as smoothness and gracility. The male skull, on the other hand, exhibits more robustness and larger muscle attachment areas, more pronounced brow ridges, squared lower jaw, etc. If the skull and pelvis are missing, determining the sex may be difficult. While various measurements and calculations are available to estimate sex from long bones and other parts of the skeleton, morphology seems a more accurate feature than size in determining sex. Age at Death The criteria used to estimate age at death depend on whether the individual is an infant, subadult, or adult. In fetal and infant remains, age can be estimated based on the length of certain bones.6 The most reliable means to estimate age in children is the development and eruption of the teeth.7 We know the developmental pattern and mean age of eruption for each tooth. The subadult skeleton also can provide information about the age at death. To allow for growth, the ends and shafts of long bones are separated by cartilage plates (epiphyses). The cartilage plates disappear and the extremities of the various long bones fuse at different ages. Similar processes take place in other bones, such as the clavicle and pelvis. By knowing the sequence of this epiphyseal union, we can estimate the age of an individual.8 In younger adults, I have found The word race is an unfortunate label for the population-based physical diversity we see in the human species around the world. The term is widely used among the lay public, however. Methods used to determine the race of skeletal remains include measurements and observations of both the skull and the postcranial skeleton. My experience has been that the skull, especially the facial region, is the most diagnostic for racial attribution. Nonmetric racial features of the skull have been outlined by Rhine13 and include such features as overall shape of the skull, shape of the nasal region, shape of the orbits, degree of protrusion of the jaw or prognathism, shape of the lower jaw, and certain features of the teeth, to name a few. Cranial and facial measurements diagnostic for race have been reported in a volume on assessing race from the skeleton,14-16 as have postcranial methods for determining race.17 Stature The most common method to estimate living height from skeletal remains is to use equations originally developed for this purpose by measuring the lengths of long bones of American casualties from World War II and the Korean War.18'19 We usually measure a leg bone, such as the femur or tibia, and use the length in the equation listed for males or females of a particular race. The result is an estimated living stature, reported as a range, such as 66 to 68 inches. Another method to estimate living stature is known as the anatomical method.2'21 The height of the skull is measured, along with components of the spine, and the lengths of the leg bones, including the ankle. To this "skeletal height" is added a correction factor for the soft tissues at the joints, scalp, and soles of

3 the feet. A major drawback of this method is that it requires a fairly complete skeleton. Methods for estimating height from the spine have been reported,22 as have methods for estimating stature from incomplete long bones.23 While these methods can be fairly accurate, they rely on antemortem records of height for comparison. Military data24 indicate that men tend to overestimate their height more than women do, and a study of heights reported on driver's licenses also showed overestimation.25 We must remember that the statures we calculate from skeletal remains are estimates. Fig 2. Healed fractures in ulna and radius with metal plates screwed to bones to stabilize bones during healing. Evidence of trauma and medical implants such as these may assist in identifying skeletal remains. Trauma Trauma seen in skeletal remains falls into three categories: 1. Antemortem 2. Perimortem 3. Postmortem Antemortem trauma includes injuries sustained during life, and evidence of healing usually exists (Fig 2). Perimortem trauma are injuries sustained at or about the time of death, and often contribute to the cause of death (Figs 3 and 4). Postmortem trauma is that which is sustained after death, usually by environmental or animal action. Antemortem injuries, such as healed broken bones or surgical implants may assist in identifying an individual or may provide evidence of a long-term pattern of injuries in child abuse. For a general discussion of trauma, the reader should consult a forensic pathology text such as the one by DiMaio and DiMaio.26 Trauma in skeletal remains is addressed by Merbs,27 and postmortem damage and influences are detailed in a text edited by Haglund and Sorg.28 Fig 3. Cranium reconstructed from 7 pieces showing an entrance gunshot wound behind the right ear. Time Since Death Estimating how long skeletal remains have been at the location where they are found is one of the most difficult questions for forensic anthropologists to answer. An estimate of the time since death can narrow the number of missing persons we compare with the unknown victim. Fig 4. Reconstructed cranium showing blunt force trauma to the face and head.

4 However, bones of a person who died 1 years ago may differ little from those that are from a person who has been dead only 5 years. Prompted by a case involving a Civil War grave mistakenly estimated to be about a year old,29'3 one of the best studies to obtain data on postmortem decomposition and changes has been undertaken by Professor Bill Bass at the University of Tennessee. Ubelaker discusses current research on estimating time since death, including the use of insects (forensic entomology).31 Establishing Individual Identity Test Your Knowledge Look for the CE Update exam on Forensics (85) in the August issue of Laboratory Medicine. Participants will earn 3 CMLE credit hours. The preferred method for establishing the identity of skeletal remains is by dental identification. If the anthropologist's general description of the deceased matches the description of a missing person, we then ask the missing person's dentist to provide dental charts and radiographs for comparison. A forensic odontologist (dentist) then compares the data to either rule out that the remains belonged to the missing person or confirm that the unknown and the records represent the same individual.32 In some cases, the teeth or skull may be missing, requiring alternatives to a dental identification. Postmortem radiographs can be compared with antemortem radiographs, if available. Cranial anatomy, especially the sinus form can be compared. Chest radiographs often show some of the vertebral detail. Evidence of healed fractures or medical implants may be used to confirm identity.33 Photographic or video superimposition can be used to superimpose the unknown skull and a portrait of an individual to see if they "fit" anatomically.34 Advances in DNA technology are making it possible to extract DNA from human bones. This will allow us to compare the DNA from skeletal remains with the DNA of family members when we have an idea who the victim is, but more traditional methods of identification are not available due to incomplete remains, etc. The military is using DNA to assist in the identification of MIA/POW remains from the Vietnam War. 426 VOLUME 29. NUMBER 7 Qualifications and Training in Forensic Anthropology The usual minimum academic preparation for work in forensic anthropology is a master's degree in physical or biological anthropology with additional training in forensic applications. Those desiring to make forensic anthropology their major professional focus, however, will normally seek the doctoral degree and board certification in forensic anthropology. My advice to those interested in pursuing a graduate education in anthropology and the practice of forensic anthropology is to contact board-certified forensic anthropologists who teach at colleges and universities for information about the programs available. A list of such instructors is available at the American Board of Forensic Anthropology (ABFA; District of Columbia) Web site: [accessed May 22, 1998]. The ABFA also offers a voluntary certification program. Requirements for certification include permanent residency in Canada or the United States, a doctoral degree in biological/physical anthropology from an accredited university, and 3 years of postdoctoral forensic experience. The applicant must also submit to a background investigation to prove his/her good moral character and pass written and practical examinations. Employment Most forensic anthropologists teach in colleges and universities or work in museums. A small number are employed by government agencies. Usually, forensic anthropologists' caseloads35 are insufficient to make a living from forensic cases alone so most forensic anthropologists serve as consultants to medical examiners or coroners and the police. Forensic science is a fascinating field, with each case presenting new questions and challenges. For me, the most rewarding aspect of my work is collaboration with forensic pathologists, forensic odontologists, police investigators, and other specialists, all cooperating to put the puzzle pieces together to identify the victim, and often to help solve a murder.

5 Acknowledgments I wish to thank Shirley Sackman, Tana Hasart, EdD, and Daniel M. Baer, MD, for their valuable comments and suggestions, and the anonymous reviewers for their thoughtful input. Very special thanks are due Patti for her love and support. Forensic Anthropology. Albuquerque, NM: Maxwell Museum of Anthropology; 199: Trotter M, Gleser G. Estimation of stature from long limb bones of American whites and Negroes. Am J Phys Anthropol. 1952;1: Trotter M, Gleser G. A re-evaluation of stature based on measurements taken during life and of long bones after death. References Am ] Phys Anthropol. 1958;16: Hunter J, Roberts C, Martin A. Studies in Crime: An Intro2. Fully G. Une nouvelle methode de determination de la duction to Forensic Archaeology. London, England: Batsford taille. Ann Med Leg. 1956;35: Archaeology Books; Lundy JK. The mathematical versus anatomical methods 2. Boddington A, Garland AN, (anaway RC. Death, Decay of stature estimate from long limb bones. Am J Forensic Med and Reconstruction: Approaches to Archaeology and Forensic Pathol. 1985;6: Science. Manchester, England; Manchester University Press; 22. Tibbets G. Estimation of stature from the vertebral col1987. umn in American blacks. / Forensic Sci. 1981;26: Stewart TD. Essentials of Forensic Anthropology: Especially 23. Steele DG. Estimation of stature from fragments of long as Developed in the United States. Springfield, 111: Charles C. limb bones. In: Stewart TD, ed. Personal Identification in Mass Thomas; Disasters. Washington, DC: National Museum of Natural His4. Krogman WM, Iscan MY. The Human Skeleton in Forensic tory; 197: Medicine. Springfield, III: Charles C. Thomas; Giles E, Hutinson DL. Stature and age-related bias in 5. Sutherland LD, Suchey )M. Use of the ventral arc in pubic self-reported stature. / Forensic Sci. 1991;36: sex determination. / Forensic Sci. 1991;36: Willey P, Falsetti T. Inaccuracy of height information on 6. Weaver DS. Forensic aspects of fetal and neonatal skeledrivers licenses. / Forensic Sci. 1991;36: tons. In: Reichs KJ, ed. Forensic Osteology: Advances in the 26. DiMaio D, DiMaio V. Forensic Pathology. New York, NY: Identification of Human Remains. Springfield, 111: Charles C. Elsevier; Thomas; 1986; Merbs CF. Trauma. In: Iscan MY, Kennedy AR, eds. 7. Ash MM. Wheeler's Dental Anatomy, Physiology, and Reconstruction of Life from the Skeleton. New York, NY: Alan R. Occulsion. Philadelphia, Pa: WB Saunders; 1984: Liss; 1989: McKern TW, Stewart TD. Skeletal Age Changes in Young 28. Haglund WD, Sorg MH, eds. Forensic Taphonomy: The American Males. Analyzed from the Standpoint of Age Identifi- Postmortem Fate of Human Remains. Boca Raton, Fla: CRC cation. Natick, Mass: Quartermaster Research and DevelopPress; ment Center; 1957; Technical Report EP Bass WM. Time interval since death: a difficult question. 9. Owings Webb PA, Suchey JM. Epiphyseal union of the In Rathbun TA, Buikstra JE, eds. Human Identification; Case anterior iliac crest and medial clavicle in a modern multiracial Studies in Forensic Anthropology. Springfield, 111: Charles C. sample of American males and females. Am ] Phys Anthropol. Thomas; 1984: ;68: Bass WM, Meadows L. Time since death and decompo1. Brooks S, Suchey )M. Skeletal age determination based sition of the human body: variables and observations in case on the os pubis: a comparison of the Acsadi-Nemeskeri and and experimental field studies. / Forensic Sci. Suchey-Brooks methods. Hum Evol. 199;3: ;35: Kerley ER, Ubelaker DH. Revisions in the microscopic 31. Ubelaker DH. Taphonomic Applications in Forensic method of estimating age at death in human cortical bone. Anthropology. In: Haglund, WD, Sorg MH, eds. Forensic Am J Phys Anthropol. 1978;49: Taphonomy: The Postmortem Fate of Human Remains. Boca 12. Iscan MY, Loth SR. Osteological manifestations of age in Raton, Fla: CRC Press; 1996;77-9. the adult. In: Iscan MY, Kennedy AR, eds. Reconstruction of 32. Bowers CM, Bell G, eds. Manual of Forensic Odontology, Life from the Skeleton. New York, NY; Alan R. Liss; 1989: rd Ed. American Society of Forensic Odontology. Ontario, 13. Rhine S. Non-metric skull racing. In: Gill GW, Rhine S, Canada: Monticore Publishers; eds. Skeletal Attribution of Race: Methods for Forensic Anthro- 33. Lundy JK. Establishing positive identification...when all pology. Albuquerque, NM: Maxwell Museum of Anthropol- else fails. / Oregon Dent Assoc. 1985;54: ogy; 199: Webster WP, Brinkhous W. Identification of human 14. Ayers HG, Jantz RL, Moore-Jansen PH. Giles and Elliot remains using photographic reconstructions. In: Reichs KJ, race discriminant functions revisited: a test using recent ed. Forensic Osteology: Advances in the Identification of Human forensic cases. In: Gill GW, Rhine S, eds. Skeletal Attribution of Remains. Springfield, 111: Charles C. Thomas; 1986: Race: Methods for Forensic Anthropology. Albuquerque, NM: 35. Reichs KJ. A professional profile of Diplomates of the Maxwell Museum of Anthropology; 199: American Board of Forensic Anthropology: / 15. Gill GW, Gilbert M. Race identification for the midfacial Forensic Sci. 1995;4: skeleton: American blacks and whites. In: Gill GW, Rhine S, eds. Skeletal Attribution of Race: Methods for Forensic Anthropology. Albuquerque, NM: Maxwell Museum of AnthropolSuggested Reading ogy; 199: Curran B. The application of measures of midfacial pro- For those looking for a more general account of forensic anthropology, two books will be of interest. Doug Ubelaker's jection for racial classification. In: Gill GW, Rhine S, eds. Skeletal Attribution of Race: Methods for Forensic Anthropology. Bones: A Forensic Detective's Casebook (Harper Collins, 1992) and the late Bill Maples' Dead Men Do Tell Tales: The Strange Albuquerque, NM: Maxwell Museum of Anthropology; and Fascinating Cases of a Forensic Anthropologist (Doubieday, 199: ) are both good reads. For those who might like mystery 17. Iscan MY, Cotton TS. Osteometric assessment of racial novels with a forensic anthropology focus, try books by Aaron affinity from multiple sites in the postcranial skeleton. In: Gill Elkins, the pen name of an anthropologist. GW, Rhine S, eds. Skeletal Attribution of Race: Methods for LABORATO