Forensic Anthropology Week 3
Forensic Anthropology Week 3 Anth 310
Edinboro University of Pennsylvania
Popular in Intro to Forensic Anthropology
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This 8 page Class Notes was uploaded by Danielle Johnson on Wednesday February 17, 2016. The Class Notes belongs to Anth 310 at Edinboro University of Pennsylvania taught by Dr. Barbian in Winter 2016. Since its upload, it has received 17 views. For similar materials see Intro to Forensic Anthropology in anthropology, evolution, sphr at Edinboro University of Pennsylvania.
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Date Created: 02/17/16
Forensic Anthropology Week 3 2/8/2016 Presumptive Identification ● Logically associate remains with a specific individual ● Investigators assign probative value to evidence ○ Based on assumptions and context ● Circumstantial evidence at the scene ○ personal effects and documents ● Problems can occur Example: Mass Grave Human Rights Excavation ● Group characteristics (age and sex) have low probative value ● Multiple decedents ○ single sex ○ same age category ○ same ancestral/ethnic group ● Artifacts with the bodies has to help separate these people out (jewelry, clothing … etc) Why use Presumptive Evidence? ● Practical realities ● Probative value of several avenues of presumptive evidence may be very high ● add it together makes it more competent ● DNA isn’t always available Example: Fractured Right Arm ● Missing persons case ○ Unknown skeletal remains with a healed fracture of the right radius and ulna ○ multiple people may have broken this particular bone ● Military aircraft crash ○ only one of the two individuals had a history of a broken right arm ○ much greater probative value Personal Identification from the Skeleton ● Biological factors ○ Idiosyncratic morphology ○ Life history variables ● Relies on known physical data ○ Personal recollections ○ Official documentation ■ Medical history ■ fingerprints ■ Retained tissue samples Idiosyncratic Morphology ● Traits unique to a specific person ○ Deoxyribonucleic acid (DNA) ■ unique except for monozygotic twins Forensic Anthropology Week 3 2/8/2016 ■ can be extracted from bone ○ Anatomical structures ■ Vary in size and morphology ■ Unique morphology must be recorded during life ● extra teeth ● missing/extra limbs Life History Variables ● Skeletal Indicators of Stress ○ Trauma ○ Disease ● Cultural Modifications ○ Medical or surgical ○ Cosmetic Biological Factors and Identification ● Compare gross feature with known information ○ radiographs or photographs ○ surgical appliances ○ bone/tooth DNA ○ Artistic renderings ○ biological Antemortem/Postmortem Radiographic Comparison ● Accomplished by gross evaluation, overlaying the films including computer/video superimposition ● Areas of interest: ○ Sinus patterns ○ Meningeal arteries ○ Transverse processes ○ Trabecular bone patterns Medical and Surgical Artifacts ● Safe Medical Devices Act (1993) ○ Require recording of lot and serial numbers of orthopaedic devices ● Enable investigator to contact manufacturer leading to identification of surgeon, hospital, and patient DNA Identification ● Nuclear DNA ○ (mostly used for) Recent remains, e.g. muscle tissue ○ One copy per cell (only one nucleus per cell) ■ not a lot of DNA to use for testing ■ tends to be more fragile Forensic Anthropology Week 3 2/8/2016 ○ Patrilineal and matrilineal descent ■ Parent to offspring ○ Can’t always get DNA Mitochondrial DNA ● Bone ● Multiple copies per cell ○ allows for multiple samples ● Matrilineal descent ○ not unique to you, shared with your maternal family ○ mother to offspring ○ easier to get a sample from a relative DNA from Bones and Teeth ● Use skeletal analysis to produce short list of possible candidates ● Comparison of nuclear DNA with known exemplar → positive identification ● mtDNA compares to known maternal relatives ○ unique sequence with large database → strong presumptive identification ● nuclear DNA Used to establish biological sex and ancestry ● Reassociate commingled remains Video Superimposition ● superimpose one video image over another ○ photograph over a skull ○ morphological features onto a radiograph ○ Antemortem radiograph onto a postmortem radiograph ○ Always use data on skin tissue thickness ○ With computers can now include facial growth parameters and degree of fit ● Exclusionary or presumptive evidence ○ Except in rare cases of unique dentition or unusual morphology ○ not used as presumptive ID ○ used to rule in and out of a category ○ used as a last resort Forensic Art and Computer Modeling ● Goal = accurate representation of decedent's facial feature ● Based on assessment of sex, ancestry and biological parameters of the skull ● May include hair, clothing and jewelry found at scene ● Blend of art and science ● One of last methods used ○ “last resort” ● Stimulate investigative leads ○ not meant to scientifically identify anyone Forensic Anthropology Week 3 2/8/2016 ● Identity established through traditional forensic techniques ● Not expected to yield positive identification Methods and Standards in Osteology Osteology 1. the branch of anatomy dealing with bones 2. the bony structure of an organism Physical Anthropology ● Forensic Anthropology ● Paleopathology ● Paleoanthropology INformation Available from the skeleton ● Age ● Sex ● Stature ● Habitual Activities ● Race/Ethnicity ● Pathology Two Methodological Approaches ● Visual Comparison ● Mathematical Approach Visual Approach ● Visual Comparison ● Investigator attaches weight to observations ○ multivariate statistical considerations ■ professional training ● beginners make mistakes ■ intuition Advantages of Visual Approach ● Less restricted in choice of variables ● Use traits that cannot be expressed as quantitative variables ○ can’t always measure everything Mathematical Approach ● Numerical Characterization (metrics) ● Computations and numerical evaluation ● Intercorrelations between variables explicit Forensic Anthropology Week 3 2/8/2016 ○ allows for statistics and percentages of probability of correctness ○ less training involved Advantages of Mathematical Approach ● Construct probabilities ● Reveal biological structures not easily observed FORDISC 3.0Personal Computer Forensic Discriminant Functions ● Computerized program that analyzes human remains ● Developed at the University of Tennessee ● Skeletal measurements from modern (post 1950) individuals of known demographic categories ● Use set of measurements taken from unidentified skull ● Creates unique multiple discriminant function formula ○ classifies skull with regard to percent likelihood that it falls into demographic categories ■ Categories selected by user ■ Posterior probabilities ■ Typicality scores ● Analysis it uses is a Best Fit Analysis (It has to give you an answer, it's best answer that fits your categories. Does not mean it's a good fit.) SucheyBrooks Female Pubic Age Determination System (Brookes & Suchey 1990) Statistical Terms ● Population ○ “Individuals living in a certain area at a certain time. As the area and time may vary widely a population may contain individuals of varying taxonomic origins.” Van Vark 1992 ○ Ex: ■ All individuals who died in the first half of the century in a town ■ All neanderthal individuals found ■ All females or all males ● Sample ○ Subgroup of a population ■ Individuals chosen independently ■ Individuals selected at random ■ Estimates the population’s parameters ● Sample Effects ○ Population does not look the same as the sample ○ Loss of diagnostic power ○ Biased results ○ Misinterpretations ■ Especially bas id sample is small Forensic Anthropology Week 3 2/8/2016 ■ With human samples this normally happens ● Mean ○ Sum of all observations divided by the number of observations total ○ Uses all observed values ○ Sensitive to outlying points ■ Good thing because of small sample sizes (uses whole sample) ■ Bad thing because of outliers (which can skew the data) ● Standard Deviation ○ Spread of observations around the mean ○ Basis for probability statements when data normally distributed ■ Bell shaped curve assuming this perfect scenario which is believed to not be probably ■ Examples that it does occur: ● Height in adults ● Blood pressure in healthy population ● Random error in laboratory measurements ■ +/ SD (standard deviation) accounts for 68% of observations ■ +/ 2 SD accounts for 95% of observations (good enough) ■ +/ 3 SD accounts for 99.7% of observation ● Confidence Interval ○ If the procedure for computing a 95% confidence interval is used over and over, 95% of the time the interval will contain the parameter. Source of Osteological Data ● Archaeological Data ● Reference Samples ● Anatomical Samples of Known Age, sex and Race ○ Hamann Todd Collection ○ Terry Collection ○ War Dead Characteristics of Archaeological Samples ● Ancient ○ Older than 100 years ○ People living differently causing life expectancy differences ○ Secular Trends ■ Different life experiences ■ example ● Height: increase of 6 inches in the past 100 years ● Life expectancy has increased ■ Closer in time eliminates the trends ● Estimated ageatdeath ● Crosssectional Forensic Anthropology Week 3 2/8/2016 ● Nonsurvivors Cemetery Samples ● Assume age transgression ● 6yr old→ 35yr old→ 85yr old ○ Assumed to grow up to the next age ○ Biological death will never be known ● Skeletal samples are made up of individuals who have not survived aka nonsurvivors Standards Developed from Archaeological Samples ● Age and Diaphyseal length ○ Ubelaher 1989 ● Sex assessment based on femoral midshaft ○ Black 1978 Characteristics of Reference Samples ● Modern ● Living ● Longitudinal ● Chronological Age ● Imaging Technology ○ Can trace a person’s development based on image technology ○ Xray or other such technology Anatomical Samples ● Historic ● Known ageatdeath ● Crosssectional (6 yr old → 35 yr old) ● Non survivors ● Biased samples collected from dissections Terry Collection ● 1,728 individuals of known age, sex, ancestry, cause of death, and pathological condition ● Age of death ranged 16 102 ● Birth dates ranged from 18221942 ● Collected between 1910s and 1960s ● Cadavers used anatomy classes in Washington University Medical School, St. Louis, Missouri ○ Unclaimed Bodies ○ Relatives donated bodies Forensic Anthropology Week 3 2/8/2016 Changes to Terry Collection ● Willed Body Law of Missouri 19556 ○ Signed release required ○ More individuals from the middle class ● Dr. Trotters collecting efforts ○ Focused on younger individuals ○ Especially white females HamannTodd Collection ● Collected from 1893 to 1930s at Western Reserve Medical School ● Unclaimed bodies from Cuyahoga County Morgue and city hospitals ● Anatomical Laws of state of Ohio ● More than 3,000 Individuals ● Detailed age, sex, ancestry, cause of death ● Reflected Cleveland's industrial development ○ Tuberculosis ○ Chauffeur's fractures Suchey Brooks Sample ● Autopsies performed at the Dept. of the Chief Medical Examinercoroner, County of Los Angeles ● Only individuals positively identified ● Collected JuneAugust of 1997 ● Homicides, Suicides, Accidents, Unexpected Natural Deaths ● Individuals born every state except Alaska and 31 foreign countries