Forensic Anthropology Flashcards
1
Q
What profile can be produced by a forensic anthropologist?
A
- The age of the deceased
- The gender of the deceased
- The stature of the deceased
- Ancestry/race of the deceased.
- Diet of the deceased.
- Evidence of any diseases.
2
Q
What do enamel growth lines show?
A
- Counting the number of Retzius growth lines in teeth show the age of the person.
- Cross striations are formed every 24 hours and can be used to estimate age to an exact day that they began forming.
- Retzius lines are formed every 6-12 days and are less accurate and determining age.
3
Q
What are the implications of estimating the age of juvenile bones?
A
- Less likely to survive in a burial environment as lower bone mineral content makes it more susceptible to decay.
- Graves of children are smaller and shallower compared to adults, making them harder to detect.
- Those dead from infanticide will be less likely to receive formal burials
- Inexperienced excavators who do not recognise small bones as a human may not make a complete recovery.
4
Q
How is age estimating using long bone length?
A
Age and long bone length are linear, across populations.
This means that age can be estimated by measuring the length of the long bones.
As age increases, the linear relationship decreases, thus reducing the reliability of the technique.
5
Q
How is stature derived from long bone length?
A
- Based on the idea that short people have short bones and tall people have longer long bones.
- Height can be reconstructed from partial measurements which can be related to regression equations to estimate height.
6
Q
What are the advantages and disadvantages of estimating stature?
A
- Not always accurate as the relationship between bone length and structure has changed with time.
- An issue is that some tables require sex and ancestry to be known which isn’t always possible.
- The advantage is there has been a strong relationship between long bone length and height, and it does not matter which bone (left or right) is used in the calculation.
7
Q
How is age estimated through ossification of the epiphyses?
A
- Long bones grow to their adult length by deposition of osseous material at the ends under the epiphyseal caps
- At a genetically predetermined time, the epiphyses fuse to the diaphyses, causing long bone growth to cease.
- By measuring the degree of fusion in young adults/juveniles, age can be estimated.
- This has been found to be quite variable and therefore is not always accurate.
8
Q
How is age estimated through tooth formation?
A
Using radiographs of the deceased’s teeth, the amount of calcification for each tooth is matched with the appropriate stage of tooth formation, which is matched to an age range.
9
Q
What are the strengths and weaknesses of age estimation through tooth formation?
A
- Requires specialists to interpret radiographs
- Information on deciduous dentition is restricted to lower canines and premolars; if not present, technique is useless.
- Schedules are divided by sex for deciduous teeth and sex and ancestry for permanent teeth - demographics must be available
10
Q
What is the Pubic Symphysis and how is it used to estimate age?
A
- Is a cartilaginous joint that sits between the pubic bones.
- When young, it exhibits ridges separated by furrows that run transversely across the surface.
- With age, the surface becomes flat with a granular look.
- In old age, the face becomes pitted and eroded.
- By measuring the phase, a mean age can be estimated for the adult, however, as age increases, the accuracy of the method decreases.
11
Q
How is age estimated through dental wear?
A
The degree of dental wear is measured in six areas of the teeth.
A matrix is used to calculate the age of the deceased from a score of each of the six areas measured.
Dental wear can be quantified by % of dentine exposure.
Is subject to lifestyle factors, such as diet, dental care, chewing techniques etc.
12
Q
How is age estimated through cranial suture closure?
A
- Cranial sutures are lines that open up in young people but close through time until they are completely obliterated at old age.
- There are three areas of the skull whose sutures close according to a rough timetable - the ectocranial, endocranial and palette.
- All areas are subject to variability, reducing effectiveness.
13
Q
Why is adult age estimates less precise than sub-adult estimates?
A
- Age-related morphological changes in adult skeleton do not progress as regularly as morphological development of the sub-adult skeleton.
- Biological processes involved in the degradation of the adult skeleton are largely influenced by environmental factors.
- There is quite a large overlap between ranges for each stage of adult age at death.
- Amongst adults, ranges are smaller for young adults and broader for older adults.
14
Q
What are key size differences between the male and female skeleton?
A
- The diameter of the head of the femur is < 43 mm in females and > 48 mm in males.
- The bicondylar width of the femur is < 72 mm in females and > 78 mm in males.
- The diameter of the head of the radius is < 21 mm in females and > 24 mm in males.
15
Q
What are the skull profile differences between males and females?
A
- Supraorbital ridge (the brow ridge) is more defined in males
- Supraorbital margin is more curved in males and more pointed in females.
- The mental eminence (chin) is wider and more angular in males than females.
- The mastoid process (prominence of the temporal bone behind the ear) is larger in males than females.
16
Q
What are the morphological differences between the male and female pelvises
A
- The female pelvis is shorter and broader, with flatter iliac blades and a wider, ovular pelvic inlet (heart-shaped in men)
- The iliac crest is less angulated in females
- The hip joint faces more anteriorly in females.
- Females have a wider sciatic notch due to a widening of the sacro-iliac joint.
17
Q
What are gender variations in the pubis?
A
- Female pubis is more rectangular, whereas the males are more square
- Female pubis appears stretched in comparison to the males.
- The subpubic angle of the male pelvis is V-shaped and less than 90o, whereas in females it is rounded.
18
Q
What influences the accuracy of sex determination?
A
- ID of sex is influenced by age, population affinities and completeness of the skeleton.
- Typical accuracies for adult skeleton are:
- 95% for whole skeletons
- 90% for pelvis alone
- 80% for the cranium alone
- 70% for long bones.
19
Q
Why is sexing juveniles difficult?
A
- Reliable sex differences only appear after puberty.
- Pre-pubescent juveniles will not have distinguishing sex characteristics.
20
Q
How do morphological features differ between populations?
A
- A European face has:
- Narrow nasal aperture
- Simple, sharp inferior nasal margin
- Palate is a narrow, parabolic curve of dental row.
- An African face has:
- Wide nasal aperture with guttered inferior margin.
- Palate is intermediate width with a hyperbolic dental row.
21
Q
What is the craniometric analysis?
A
It uses anthropometric points and looks at paired landmarks and unpaired landmarks to determine race.
22
Q
What is the cranial index?
A
- A numerical device for characterising the size of a skull.
- Dolichocephalic means a relatively long, thin skull
- Brachycephalic means a relatively broad, short skull.
23
Q
What is Geometric Morphometrics?
A
- Uses coordinates of the anatomical landmarks
- Can account for size differences in the skull.
- Can give an appreciation of shape differences, unlike craniometric analysis.
24
Q
How may scavengers affect the biological profile?
A
- Can scatter bones, break them through trampling or by chewing bony elements.
- Pits are marks that fail to penetrate through the bone. These look like those caused by sharp instruments, and thus can mislead the investigator into thinking there was sharp-force trauma.
- Punctures are areas of collapsed bone. Resemble projectile wounds through thin section of bone.
25
What effect does fire have on a bone?
* Exposure to fire causes a number of distinct changes in bone beyond charring and discolouration.
* After being completely burned, only the calcium salts deposited in the bone during growth remain.
* The bone can be broken by the slightest ill-treatment, affecting the use of bones in creating a biological profile.
* Affects stature calculation, age and sex determination.
* Bones can shrink above 700 oC, leading to incorrect profile.
26
What effect does weathering have on bones?
* Exposure to sunlight dries out the bone, causing all dimensions to decrease in size.
* The bone can crack to relieve tension between the cortex and the underlying bone.
* Can lead to incorrect stature calculations, age estimations and sex determinations.
27
What are the different types of long bone fractures?
* Partial or complete - either the bone partially breaks or completely breaks.
* Closed/open - the bone either penetrates through the skin, or the skin remains intact.
* Impact - the ends of a fractured bone are jammed together through force
* Pathological - caused by weakening of the bone through disease.
28
What are the two types of sharp-force trauma, and what is characteristic of each type?
* Glancing blow trauma is where the sharp instrument poorly connects with the bone.
* Characterised by jagged, poorly defined edges that are rough.
* Direct blow is where the sharp instrument makes direct contact with the bone.
* Causes a linear slice, with well-defined, flat, smooth edges.
* Microscopic scratch marks may also be present.
29
What are the two types of blunt force trauma, and what is characteristic of each type?
* High force blunt trauma is characterised by radiating AND concentric lines. There is also inward bevelling of the point of impact due to the pressure bending the skull inwards.
* Low force blunt trauma is characterised by only radiating fractures.
30
What is characteristic of projectile trauma?
* Entrance and exit wounds should be present.
* Entrance wounds will be smaller, rounder, bevelled inwards with radiating fracture lines
* Exit wounds (if present) are larger, irregular and bevelled outwards.
* Power of the weapon dictates whether concentric lines will be present.
31
What information is obtained from ante-mortem trauma?
* Porosity near the breaks indicates bone activity and resorption; contrasts with usual smooth surface.
* Bone remodelling due to trauma, which causes the borders of broken/fractured surfaces to become blunt, losing sharpness; can occur 1 week after break.
* Callus develops six weeks after the break; covers bone ends and can extend some distance away from the local area of the break. Cannot occur at TOD.
32
What is characteristic of perimortem trauma?
* Perimortem trauma is indicated by sharp edges of borders of broken surfaces and fracture lines; irregular due to no remodelling.
* Hinging may be present, where a section of the bone is bent away from the direction of the blow - only occurs if the bone is moist.
* The formation of fracture lines can only occur when the bone is moist - distinguishes postmortem and perimortem.
* Broken ends are angled with a jagged surface.
33
What information can be obtained from postmortem trauma?
* Breaks in dead, dry bone rarely exhibit fracture lines, as it snaps like a dry twig.
* Long bones break nearly at right angles; nearly flat ends and no signs of healing.
* Trauma colour indicates whether the trauma is postmortem
* The broken surface is usually lighter in colour due to uncovering of the original off-white colour.
34
How is diet reconstructed from hard dental tissue?
* Diet leaves behind chemical signatures:
* Stable carbon isotopes differ in diet. C12/C14 and N14/N15 isotopes are found in varying concentrations depending on the protein that is consumed in the diet.
* Looking at dental microwear (dental pits and scratches) may show dietary hardness/abrasiveness
* Dental diseases such as caries are linked to dietary carbohydrates.
