LECTURE 3: FORENSIC ANTHROPOLOGY // CHAPTER 8 Flashcards
Define forensic anthropology
- identification of human (can be animal) remains (fresh, partially or completely decomposed) for legal purposes
- uses osteology, anatomy, metrics, and radio imaging to identify individual and cause and mechanism of death
The role of a forensic anthropologist
Biological identification
- species
- gender/ sex
- age
- biological group/ethnicity
- stature
- pathology
Personal identification
- odontology
- pathology
- emispheric dominance
- genetics
- facial reconstruction
- provenancing
- post-mortem interval
determining sex
- male/female pelvis
- female pelvis is wider with longer horizontal diameter
- femoral and radial head diameter
- femoral (female < 43mm) (male > 48mm)
- radial (female < 21mm) (male > 23mm)
all are either greater/smaller and equal
determining age
- public symphysis
hip bones change with age - ridges in the bone disappear and the boarder becomes less defined
in old age pitting occurs - Iscan method
examination of the 4th left rib
starts smooth and changes with age - Clavicle medial epiphysis
examination of the clavicle - flakes form over age stages
determining ancestry
- skull measurements
- Femoral Head Torsion Angle (with reference to diaphysis and condyles): wide in asians, very small to none in negroids, intermediate in caucasoids.
- shape of hair when cut in a cross-section
- skin distribution of pigment
determination of stature
- formulas/tables based on long bone length or vertebral body height
- only an estimation as living people have soft tissue
Post mortem interval
- Time since death / how long the body has been dead
- 4 stages:
• Fresh body
• Bloating, skin slippage, imperfection
• Much body lost and draining of fluids, decomposition
• Skeletonization
4 main functions of skeleton
1) Support – provides infrastructure for attachment and support of softer tissues
2) Motion – these attachments allow bones to acts as levers
3) Protection – bones protect soft organs from physical damage
4) Growth – bones are centres for growth and RBC production, readily available calcium source
1) Endochondral ossification
- Bone grows by replacing cartilage
- Growth starts with a ‘model’ of a bone consisting of cartilage and centres of ossification
- From these centres bone is produced and infiltrates the cartilage model
- Developing shaft (diaphysis) and ends (epiphysis)
- These areas then meet and bone knits together
- Not all epiphysis unite at the same time – can be used for estimating age for those below 25 years old
2) Intramembranous ossification
- Bone grows from mesenchymal connective tissue
- Ossification occurs within a membrane rather than cartilage
Bone cells
Osteoblasts:
- produce bone (osseus tissue) and deposit it in layers
Osteocytes:
- maintain matrix
Osteoclasts:
- Resorb and remodel bone as required for growth - these are giant, multinuclear, phagocytic, and osteolytic cells
Sex determination - Pelvis
METHOD MALE FEMALE
Pelvis in general Large, rugged Smaller, gracile
Subpubic concavity Narrow Wide
Acetabulum Large Medium to small
Sciatic notch Narrow Wide
Preauricular sulcus Absent May be present
Ventral arc Absent or very small Present, can be strongly
Subpubic concavity Absent/shallowPresent/can be deep
Ischiopubic ramus. Thin, narrow Wide, possible ridge
Sex determination - Cranium
- Males tend to be larger with more muscle attachments
- Areas of interest:
Brow ridges, mastoid processes, occipital area, upper palate, general architecture - Metric enthusiasm extends to determination of sex
- Measurements are taken with specialised rulers (callipers – either spreading callipers or sliding callipers)
- Take references and compare against reference population’
- Postcranial bones can help but most info is from measurements – quantitative measures
Determining age - Pubic symphysis
- Is the junction of the two pubic bones lying roughly 4-5in below the navel
- The junction is bridged by cartilage that acts as a cushion bet the two bones
- The symphyseal surface is a raised platform that changes from a rough, rugged surface to a smooth well-defined area
- Considered most reliable morphologic indicator of age at death
Determining age - Ribs
- Sternal end of end of fourth left rib
- As cartilage between rib and sternum ages, it begins to ossify at a known an predictable rate
Determining age - Sacroiliac joint
- Changes in auricular surface where ilium attaches to sacrum (sacroiliac joint)
- As age progresses the surface of bone becomes less bumpy and more smooth, with smallish pores opening up – a decrease in the surface organisation traits
Determining age - Remodelling
- Constantly remodelling in response to stresses placed on it, seen in the microscopic structure of bone
- Constant erosion and renewal of bone leaves permanent markers in bone and once we die, these changes cease – correlation between the amount of bone reworking and the amount of time the body has expended energy on this remodelling
- Sample taken – microscope; whole osteons, fragmented osteons, interstitial bone fragments – only downside is taking the sample off evidence, may not be allowed due to case requirements
Determining ancestry - skull
- White, black, Hispanics, Asians, native American, other
- Can be estimated by morphological or quantitate analysis – both centred around skull
- Morphological features
General structure
Eye orbits
Nasal aperture
Dentition
Surrounding bones of face
Scooped-out appearance of lingual side of upper central incisors (often found in Asian ancestry) // some native Americans show shovel-shaping on incisors - Metric means of categorising human populations was established
- Fairly accurate but based on historic populations not modern populations
Determining Stature
- Length of long bones, especially lower limb
- Sex and ancestry are required to correctly estimate – as humans vary within and between these categories
Cause vs. manner of death
- Cause is the action that initiates cessation of life
- Manner is the way in which death came about: natural, accidental, suicide, homicide
Odontology
- Conducted by comparisons of dental remains to either antemortem or post-mortem records – antemortem comparison are most common
- Forensic dentist produces post-mortem records by descriptions of dental structures and taking radiographs
- Comparison between post and ante can then be done
- Fillings, gaps and restorations are main points of identification or even good hygiene and few restorations
- Noting similarities and discrepancies
