Exam 2 Study Guide.docx

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Department
Anthropology (Science and Mathematics)
Course Code
ASM 275
Professor
Christopher Stojanowski

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ASM 275: ForensicAnthropology Exam 2 Study Guide 1.Basic elements of initial forensic examination should Identify basic demographic information Screen for features leading to a positive identification 2.Reconstruct cause of death, manner of death, help interpret crime scene (unit 3) SexAssessment: -Know the techniques for assessing sex and which are most and least accurate. -Know what features are associated with each sex (for example, ventral arc presence is a female condition) Sexing- discriminating between male and female 1. metric (measurement based) 2. non-metric (not measurement based) Aging- estimation of an individuals age of death 1. absolute age 2. age class (e.g. prenatal; infant 0-3, child 3-12….) 3. Seriation- relative age; youngest to oldest Ancestry- estimation of heritage, race/population affinity Estimating stature- determining height of indidual Use relationship between some measureable feature to height: regression analysis By determing sex, you eliminate 50% of pool of missing people -women give birth and men don’t= restructuring of pelvis -men tend to be larger than women, again evolutionary history of children Determining biological sex: male, female, indeterminate Based on sexual dimorphism NOT gender (social term) Methods Metric- dimensions with breakpoints (ex max diameter of humeral or femoral head) -if larger than X, male; if smaller than X, female Nonmetric- more accurate -pelvic morphology (shape or appearance) -cranial morphology Assessing Sex from the Skeleton Order of accuracy: Pelvis- primary sexual characteristics Can be 95% accurate Cranium- secondary sexual characteristics Postcranium and dentition- bases on sexual dimorphism Can only use this for ADULTS ONLY! Sex characteristics of skeleton (pelvis and skull) don’t form until advanced adolescent, early 20s and even 30s Terms: *Sexual dimorphism : sex-based two forms tendency for males and females of a species to vary in size, males being larger in primates males have sharp ridges on top of skull- muscle attachment sites have larger, sharp pointy canines   *Non-metric vs. metric variables *Pelvic morphology: can be 95% accurate Sub-pubic angle: female has much wider sub-pubic angle; males like 90deg Iliac “Flare”- what gives women hips- male have smaller angle, no flare out Top portion called ilium, and it is wider and flare in women Pelvis inlet- males have narrow or small pelvic inlet (size of red arrow) Females need more room to give birth For only portions of the pelvis: Pubic bone most informative (red part) Isn’t very dense though, so it can break down pretty easily 5 Primary observations: 1. Sciatic notch morphology (red arrow): preserves the best, densest part 2.Ventral arc 3. Subpubic concavity 4. schio-pubic ramus ridge 5. Pubic bone size/width *Shape of sacrum Sciatic Notch Morphology Ox coxa:  Male: narrow Female: wide to allow birth Female Male Male   Phenice’s Technique: 1969: focus on pubic bone; if you have all 3, 95% of sex Ventral Arc­ raised area of bone that is only present in females Subpubic concavity­ looking through pubic bone, looking out front of body  (posterior/ dorsal side of pubic bone) Straight, even convex, profile into ischium for men Concave in female       Indicates female because of concavity Ichiopubic ramus ridge­ medial aspect of pubic bone, just below face of pubis;  raised piece of bone only in females Looks like someone grabbed the boned and pinched it and made a ridge in  FEMALES Pubic bone size: how wide it is (not part of Phenice) *Sex-SpecificAspects of CranialAnatomy: use when no pelvic remains not as high of a degree of accuracy, ~90% use 5 things 1. Mastoid Process- hard bumpy piece of bone behind ear Male has much larger, larger in volume and extends farther down from ear hole Protrudes more 2.Nuchal Crest where neck muscles attach males have larger neck muscles ergo larger nuchal crest how much raised bone there is in the back of the skull very little= female elaborate hook like features= male 3.Supraorbital Margins above the orbit margin stick eyes on outside portion of upper orbits and feel how thick it is Much thicker in males, thinner in females 4.Glabella projection area between eyes, above nose females have small glabellas and don’t project very far in profile males have larger brow ridges and more projection 5.Mandible/chin development degree of development of chin females have poorly developed, defined males are defined and developed (right side of schematic) -Forehead profile females have more vertical, males or more sloping foreheads -Frontal/Parietal bossing gentle general inflating of forehead region, as well as sides of head -Root of Cheek bone males- go well back behind ear females- tends to stop where earhole is Caveats for cranial distinctions Less accurate than pelvis for sex determination Skull is plastic- responds to mechanical forces and can change over course of lifetime Activities such as carrying loads on head will increase rugosity in males, femals Female skull become more “masculinized” with increasing age (postmenopausal) Loss of teeth change shape of jaw in men, women with extensive alveolar resorption Male; lack of forehead, more sloping; glabella is very well defined and forward projecting; top of orbit is quite thick MALE -projecting glabella - sloping forehead -large mastoid process -not much nuchal crest development -red arrow: root of cheekbone well behind earhole -blue line: size of cheekbone FEMALE - not glabella -much more vertical forehead -mastoid process much smaller -nuchal area in back of skull very rounded, little extra bone red arrow: root of cheek near earhole Smaller cheek bone height Much more grasile, less Metric Measurements *Population Specific: metric based ^^^^^^ Accuracy: how close a measures value is to the actual/true value (degree of veracity, systematic error, near bullseye) Precision: how close the measured values are to one another (degree of reproducibility, or dispersion) Males on average how longer tibia Male and female clavicle Male and female femur head Female and Male ankle bone (Talus) -Focus on weight bearing bones lower limb more sexually dimorphic than upper limbs dimensions of width or breadth are better than dimensions of length femur neck height (Y) vs. width of diameter of femoral head (X) Both male femora, but there is still lots of variation in length, shape, curvature Humerus- female humerus larger than male in different populations (vice versa) Tooth sexual dimorphism -based on same basic principle as postcrania: males bigger teeth than females in POPULATION canines/molars most useful 6-9% incisors least useful 102% *Subadults: CAN use teeth for sexing subadults BabyAND adult teeth sexually dimorphic Adult teeth more sexually dimorphic First permanent molar erupts about 6 months old, followed by incisors -Deciduous Tooth Crown Dimensions- baby teeth are sexually dimorphic Adult tooth crown dimensions- because adult teeth form and erupt in childhood Above white line: baby teeth; red lines show how teeth are measures -DNA Sexing can be used for small fragments of bones or teeth look for sex-specific DNA markers XY/XX CONS: is destructive to bone, expensive, subject to contamination, used for only highest profile cases Age Estimation- know the different techniques, as well as the pros and cons of each Top out at ~50-60 years old Estimation of an individual’s age of death Try to correlate chronological age (actual age when they died) vs biological age (developmental and degenerate age expressed in body) May not be highly correlated, “age beyond your years” or younger Differences between males and females in aging POPULATION SPECIFICITY- some may age differently Absolute vs relative age- want absolute, in calendar year, age or an age category Seriation (relative age) Age based on age of other skeletons in a sample (ex this skel. Is older than this skel, etc) More useful in archaeology than forensics Use different approach depending on age of skeleton/person Subadults: age estimation based on growth processes throughout the body Adults: age estimation based on joint deterioration after body has completed growth Subadults—these techniques are based on growth and development -more accurate than adult aging techniques -sex specific, females advanced over males of same age in terms of development -based on European growth standards, often from poor house or indigent (homeless) samples around turn of century -population specific, can create a problem 1. Dental development: crown and root completion, eruption 2. Skeletal development: appearance of ossification centers, fusion of ossification centers and epiphyses, females more advanced 3. Metric data: long bone lengths *Dental Formation Patterns teeth grow from crown toward root: root last thing to finish growing use data from known cases to generate growth curves Pros: highly accurate, can be used for fetal through teenage ages, can age 1 tooth if it happened to still be growing at time of death Cons: can be sex and population specific Deciduous teeth on sides, adult teeth on middle Tooth: mandibular P3 (red box) 1: crown mineralization begin stage: ~age 1 2: crown complete stage: ~age 6 4. root complete stage: ~age 13 erupts ~age 10 *Dental Eruption Patterns: teeth fairly fully formed by eruption through gum based on eruption of teeth through gum-line requires near complete mouth to assess patterning of teeth less accurate than dental formation population specific First molar erupts around 5-6, picture shows mixed dentition (none of permanent teeth have erupted yet), individual ~4 Deciduous teeth begin mineralizing 4 months before birth/ 5 months in utero Most deciduous teeth forming at birth and in bone but not erupted About age 1 (9 months +- 2 months) first teeth (incisors, front of mouth) erupting Permanent incisors and molars forming By age 3, all deciduous teeth erupted, adult teeth really starting to form Age 6: landmark age: first permanent molar erupts through gumline Losing front teeth: ~7 deciduous incisors lost and permanent erupt through gum, first molar present Lose last baby tooth ~10-11 Eruption of second molar ~12 *Long Bone Length: no teeth to use? Use long bones that increase in size as children age certain sizes associated with age ex 200mm tibia ~6 Cons: population specific, (if adult population varies in height of pop x vs y, reach certain long bone lengths at different ages Inaccuracy increases with increasing bone length and age (ex teenage growth spurt variable) Long bone length less accurate than dental standards Requires complete long bone, can’t use fragmentary *EpiphysialAppearance: diaphysis= primary growth center, epiphyses= secondary growth center that mineralizes after diaphysis 206 bones form from 800 different growth centers, epiphyses age of appearance of each center is known approximately, looking at xrays for epiphysis presence Cons: based on large part on preservation and complete recovery of skeleton Is the epiphysis missing, or improperly collected? *Epiphysial Closure once an epiphysis appears and is fully formed, it will fuse to diaphysis to form adult bone tibia and fibula; white arrows are line of recent fusion epiph and diaph are fusing along this line but not completed yet; age about 16-22 (red) 1: epiph not formed yet; measure length of bone and compare to growth chart 2: femur length diaph has increased, little dot is diaph 3: use length of long bone 4: use length of long bone 5: epiph and diaph have fused 6: adult femur, can’t use it really unless to say older than 18 EXAMPLES Red box: deciduous incisors erupted, fully in eclusion White arrows: deciduous canines still within bone and not erupted Red arrows: first deciduous molars not yet erupted
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