WEEK 4-taphonomic studies of human remains

Question 1

Taphonomic

Answer 1

study of how organisms decay and become fossilized

Biosphere to lithosphere

Question 2

Taphonic processes- the biological and physical changes that occur

Answer 2

• post mortem= before burial
• post burial= before excavation
• Post excavation= before study

Question 3

What does taphonomy help the investigator determine?

Answer 3

The depositional history of a given set of skeletal remains
identify agents of modification and destruction
cultural activates as opposed to natural changes- human intervention?
biases of human composition

Question 4

Agents, processes and factors?

Answer 4

1. Agents- source which causes the modification eg. human, animal
2. process- action performed by the agent that causes the modification eg. scavenging butchery
3. factor- chemical, physical, biological, cultural

Question 5

Why was it originally developed?

Answer 5

for palaeontology to explain how and why extent animals become fossilised and preserved in the geological record

Question 6

taphonomy impetus from research advances in forensic anthropholgy

Answer 6

Understanding the post mortem history of human skeletal remains, trauma analysis, violence vs excavation damage

Question 7

How can you tell whether remains are human or animal?

Answer 7

Surface of animal bones are more polished and bones are more denser

Question 8

How can you tell if bones are modern or archaeological?

Answer 8

Modern bones has organic collagen component present, it is heavier and denser and has a more greasy feel
archaeological= more rougher

Question 9

Assessing the condition of the bones

Answer 9

• Completeness- % of skeleton present
• fragmentation-post mortem breakage
• preservation- condition of the cortical surfaces (erosion, burning, weathering)

Question 10

Scavenging affect on bones

Answer 10

canviores disarticulate animal carcasses in a regular sequence
early - femur from hip, mandible from cranium, atlas from cranium, humerus from scapula, caudal vertebrae, distal phalanges
middle- femur to hip bone, tibia from femur, tarsals, metatarsals, ribs, humerus from radius, carpals, metacarpals etc
late- sacrum from hip, cervical thoracic and lumbar vertebrae

Question 11

Fragmentation- incidental

Answer 11

• Disturbance in burial
• breakage during excavation- depending on condition of soil, breaking bones,
• trampling
• peri-mortem fracturing

Question 12

Intentional fragmentation

Answer 12

• Peri mortem fracturing- can result from interpersonal violence
• butchery- animal
• amputation/ disemberment

Question 13

Bone surface modification- like amputation with saw

Answer 13

sharp edges would suggest patient did not survive

could also be intentional disposal of human body parts

Question 14

Intrinsic preservation factors of bone degradation

Answer 14

size- larger bones more likely to survive
porosity
amount of compact or cancellous bone- high amounts of cancellous vs compact

Question 15

extrinsic Factors for preserving bone degradation

Answer 15

Soil PH- more acidic causes pitting of bone together and thinning of cortical bone margins
Presence of H20 and O2
temp
microbial organisms- action of bacteria is driving decay
duration of burial

Question 16

Recording surface preservation (brickley et al 2004)

Answer 16

0) absence of modification of surface
3) most surface affected with some details obscured
5) heavy erosion of surface and modifying profile
* increase degradation down scale

Question 17

Fluvial transport and dispersal

Answer 17

Action of water on bone, influence of water currents on preservation
fluvial dispersal on bones depends on bone shape and density

Question 18

Fluvial dispersal bone groups

Answer 18

1- light bones that tend to float and are easily moved: ribs, vertebrae, sacrum, sternum
2- intermediate bones that sink and are intermittently lomved- long bones, scapula, pelvis, metapodials, phalanges
3- dense bones that sink and are relatively immobile, forming a lag deposit : mandible, animal skull, deer antler

Question 19

How can you tell if there is carnivore and rodent gnawing?

Answer 19

Puncture marks and removal of epiphyses (human bone)- tend to be around the long bones
Chiselling pattern
*rodents gnaw to wear down their teeth

Question 20

Criteria for identifying cutmarks by structural features

Answer 20

• linearity of groove
• steep sided, v shaped cross section
• parallel scratch marks along walls-shouldering of displaced bone
• regularity in deep groove

Question 21

Criteria for identifying cutmarks by location

Answer 21

• purposive anatomical location
• clustering of grooves, repeated in location and direction
• directionality

Question 22

What marks are made by trampling?

Answer 22

rough and random marks , not linear cuts

Question 23

Marks on bones by root marks?

Answer 23

root grow around skeleton and leave impressions on it
more sinuous impressions
randomly occurring
chemical etching may leave residue of discolouration

Question 24

Marks from teeth

Answer 24

going around bone rather then in it

Question 25

Curation damage

Answer 25

V shaped, random, projecting regions light colour clean groove *anything happening to remains after excavation

Question 26

What do cutmarks on animals indicate?

Answer 26

Butchary at the joints | humans= body disposal, cannibalism, burial, ritual

Question 27

Speed of bone decay can depend on intrinsic influences

Answer 27

- age- children faster decay - sex - health problem- someone suffering from acute or chronic disease- sepsis

Question 28

Extrinsic factors for speed of bone decay

Answer 28

``` climate and temp depth of burial soil type PH, O2 ,H20 insects and scavengers bacteria ```

Question 29

What happens if human remains are left above ground

Answer 29

weather, insects and carnivores | normal conditions- loss of soft tissue, leave only bone and teeth

Question 30

How does mummification affect bone decay?

Answer 30

if bacteria cant survive in certain conditions, you wont see the same decay preservation of soft tissue

Question 31

Rate of decay underground

Answer 31

4x more slowly | depends on depth and type of burial

Question 32

What is fossilation

Answer 32

process where remains are embedded into sediment | soft tissue decay, minerals infill bone and form crystals, causing hardening

Question 33

Rate of decay underwater

Answer 33

Slower than bodies exposed to air- less O2 and lower temp different type of scavengers currents of water influence dispersal some bodies float some stay submerged

Question 34

Bog bodies

Answer 34

natural mummification highly acidic water, anoxic conditions preservations of internal organs and skin Bones are generally not that well preserved bc of high acidity

Question 35

What is a cremation

Answer 35

funeral rite cremated skeletal remains can survive across acidic soil burned- not efficient, difficult, requires high temperatures over prolonged period of time

Question 36

What is the weight of cremated remains?

Answer 36

0.2-2kg

Question 37

Increasing the heat affect on colour change

Answer 37

200 degrees- natural colour 500- darkens to blue/ black 800- white

Question 38

Physical changes in bone during cremation when heat is increased

Answer 38

200- dehydration 300- conversion of organics 500- loss of organics, shrinkage and some discolouration 800- conversion of hydroxyapatite to tricalcium phosphate, shrinkage, more discolouration, cracking

Question 39

structure of bone and composition

Answer 39

myriad of circular structures (osteons) with an outer layer of straight lamellar bone each osteon has a central canal (haversian canal) where nutrient vessels pass through layers contain both inorganic and organic structures- mostly collagen

Question 40

What do the miscroscopic view of human bones show

Answer 40

Plain light- inorganic component of bone Polarised light- osteons 'light up'- birefringence and a cross structure can be seen dissecting each osteon (bc collagen fibres transve in different directions and so break the light differently)

Question 41

Measures of microbial decay

Answer 41

useful to see how much microbial infiltration is going on

Question 42

Histology

Answer 42

microbial damaged bone shows localised mineral alteration and loss of birefringence

Question 43

Porosimetry

Answer 43

increase in porosity at 0.6-1.2 micrometres

Question 44

Crystallinity

Answer 44

increase in minimum dimension of apatite crystals above ~5nm

Question 45

example measurement of microscopic degradation

Answer 45

good external cortical preservation dark areas are bacterial tunnelling below the periosteal and endosteal surfaces microscopic longitudinal section through the cortex shows pattern of bacterial tunnelling

Question 46

Poorly preserved bone shown in polarised light

Answer 46

Due to microbal sction very limited reflection of collagen fibres big patches showing loss of quality and distinctive maltese crosses Cremation- loss of optical birefringence due to heat damage to collagen

Question 47

Mechanism 1 of bone degradation pathway

Answer 47

Hydrolysis of bone collagen--- infilling of interstitial pore spaces--- fossilisation

Question 48

Mechanism 2 of bone degradation pathway

Answer 48

dissolution of bone mineral--- chemical or microbial collagen degradation-- complete loss

Question 49

Mechanism 3 of bone degradation pathway

Answer 49

microbial attack of organic component--- focal destruction and re-crystallisation --- partial loss