Biological Profile- Ancestry PDF

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Summary

Amanda Friend...

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The concept of "race" ◦ Does race exist? • Yes and no • Not a biological reality • Race has a social reality, but is not a valid biological entity ◦ Continuous spectrum of variation; no discrete groups

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Biological Ancestry: ◦ Based on the preponderance of metric (things you're measuring) and non- metric skeletal traits, distributed along broad geographic- population lines.

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Why Determine "Race"? ◦ Forensic anthropologists are applied anthropologists • Interact with lay persons (law enforcement/ public). • Social context • Provide a service (use terminology that lay people understand).

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Ancestry in Forensic Anthropology ◦ Ancestry: broad, geographically- defined biological populations. ◦ Ancestry categories used must reflect everyday use in our society.

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Determining Ancestry: ◦ Three main biological ancestry groups in the US 1. Asian & Native American (Native Americans have similar skeletal traits to Asians) 2. European 3. African ◦ Non- metric (morphological) ◦ Metric (measuring) ◦ Skull (cranium and mandible) is the best place to look for ancestry ◦ With caution, use postcranial elements

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Non- Metric Traits ◦ Visually determined ◦ Not easily measured ◦ Normal skeletal variants ◦ Not pathologic or traumatic 1 Be careful or not score it at all b/c it effects how you are assessing the trait Non- Metric Traits must be: ◦ Documented for large samples 1 Large data sets ◦ Clearly illustrated and unambiguously defined 1 Other people know what you're talking about 1 Want a method that other people can use ◦ Rigorously quantified Scoring Non- Metric Traits ◦ 2 methods 1 Present or absent ▪ Complete, incomplete

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1 Quasicontinuous ▪ Small, medium, large ◦ Methods that anyone could be able to use. Determining Ancestry: Non- Metric ◦ Traits (facial skeleton): 1 Interorbital breadth: distance between eyes ▪ Scored as: • Broad • Intermediate • Narrow 1 Orbit shape 1 Nasal aperture ▪ Width of the nasal aperture is scored as: • Wide • Medium • Narrow ▪ Scored relative to the entire midface 1 Nasal bone shape/ form ▪ Scored as: • Round (quonset hut) • Oval • Plateaued (tented) • Vaulted • Triangular (steepled) 1 Midface prognathism 1 Shape of the zygomatics 1 Inferior nasal aperture ▪ Scored as: • Guttered • Incipient

• Straight • Partial sill • Complete sill 1 Post- bregmatic depression: small concavity on the sagittal suture past bregma ▪ !

◦ Traits (other): 1 Dental 1 Sutures ▪ Zygomaticomaxillary suture: • Scored as: • Angled • Smooth • S- shaped • Obilterated 1 Mandible ▪ Shape, rusticity 1 Skull form 1 Palate shape: ▪ Scored as: • Parabolic • M3 molars are pushed in • Rounded • Hyperbolic • M3 molars are angled out 1 Midface: ▪ Asian: flatter face, rounded cranial vault, anterior projecting zygomatics ▪ African: long cranial vault, intermediate zygomatics

▪ European: medium cranial vault, midfacial prog, prom chin ! •

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Non- Metric Associated with African Ancestry ◦ Square orbits ◦ Quonset hut nasals ◦ Guttered nasal area with no nasal sill • Oval nasal bones ◦ Post bregmatic depression ◦ Simple suture pattern ◦ Slanted ascending ramus ◦ Rectangular palate ◦ Alveolar prognathism ◦ Vertical zygomatics ◦ Multiple mental foramina Determining Ancestry: Non- Metric- African ◦ Wide nasal aperture ◦ Rectangular orbits ◦ Broad interorbital breadth ◦ Quonset- hut nasal bones ◦ Long headed (long cranial vault) ◦ Anterior facial prognathism ◦ Small nasal spine Non- Metrics Associated with European Ancestry ◦ Sloping orbits ◦ Tower or church steeple nasals ◦ Often have trace of metopic suture ◦ Depressed nasion ◦ Large nasal spine

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◦ Sharp nasal sill ◦ Simple suture pattern ◦ Pinched ascending ramus ◦ Parabolic palate ◦ Retreating zygomatics ◦ Prominent chin Determining Ancestry: Non- Metric- European ◦ Includes all populations of European descent ◦ Receding zygomatics ◦ Narrow nasal aperture ◦ Narrow interorbital breadth ◦ Steepled nasal bones ◦ Long headed ◦ No facial prognathism ◦ Large nasal spine Non- Metrics Associated with Asian/ Native American Ancestry ◦ Rounded orbits ◦ Tented nasals ◦ Malar tubercle ◦ Indistinct nasal sill ◦ Complex suture pattern ◦ Wide, vertical ascending ramus ◦ Straight palatine suture ◦ Round palatine ◦ Shoveled incisors ◦ Buccal pits ◦ Wormian bones ◦ Projecting (anteriorly) zygomatics

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Determining Ancestry- Asian ◦ Comparatively flat face ◦ Forward projecting zygomatics ◦ Medium width nasal aperture ◦ Rounded orbits ◦ Tented nasal bones ◦ Brachycephalic • Round headed • Wider breadth ◦ Little facial prognathism ◦ Moderate nasal spine ◦ Shovel- shaped incisors

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There are no human skeletal markers that correspond perfectly to a geographical origin. Be sure to look at many traits, not just one.

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Disadvantages on Non- Metric Analysis ◦ Inter- observer Error • Assessment is subjective • More experienced people can make better guesses on ancestry. ◦ Not clearly defined • Possible intra- observer error ◦ Rudimentary statistics • Simple trait frequencies

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Metric Analysis ◦ Standardized measurements validated with statistics

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◦ 1962: Giles and Elliot take measurements to assess ancestry • Use discriminant function analysis • Separated between African and European ancestry ◦ UT: Forensic Databank

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Metric Analysis and Fordisc ◦ Measure the remains and then enter the data into FORDISC • Computes the likelihood of the skeleton belonging to a particular ancestral population • Compares skeleton to other reference samples of known ancestry ◦ European and African ancestry are skewed towards Western European and Western African ◦ FORDISC will always classify

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The true nature of human variation ◦ Large specturm The public perception of human variation ◦ Discrete groups ◦ Not true

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