Week 3 - Forensic Taphonomy

Question 1

taphonomy

Answer 1

• > the study of processes that biological organisms undergo as they lead to fossilization
• > they study of processes as we decompose and become a bare skeleton

Question 2

forensic taphonomy

Answer 2

• > study the post mortem processes which affect the preservation and recovery of human remains from time of death to time of recovery

Question 3

what does forensic taphonomy research do?

Answer 3

• > reconstructs events surrounding and following the death
• > helps with context of discovery
• > estimate the post-mortem interval
• > identify trauma and other effects of human modification

Question 4

Post-Mortem Interval (PMI)

Answer 4

amount of time that has elapse since the death of the individual

Question 5

what are the three methods used to determine TOD

Answer 5

1. Algor Mortis
2. Rigor Mortis
3. Liver mortis
   - > after 24hrs, these methods become unreliable

Question 6

algor mortis

Answer 6

• > the cooling of the body after death (98.6 degrees during life)
• > body begins to cool down to the temperature of the surrounding environment
• > usually, the body cools down at 1degree/hour for the first 12 hours (dependant on the environmental conditions

Question 7

rigor mortis

Answer 7

• > muscle stiffening caused by the binding together of the muscle fibres
• > typically seen first in the jaw and face
• > sets in several hours after death, peaks at 12 hours, subsides over the next day when decomp of the muscle fibres sets in
• > dependant on environmental conditions or activity at time of death

Question 8

livor mortis

Answer 8

• > pooling of blood due to gravity and lack of blood circulation
• > some pressure points hinder this as the weight of your body on theses portions doesn’t allow much blood to enter and pool (see picture)
• > typically begins 30mins - 4hrs after death
• > fixed and unfixed (if body is moved blood has coagulated then the pooling areas can change

Question 9

decomposition

Answer 9

the breakdown or destruction of organic tissues resulting in the loss of all components of a biological organism

Question 10

2 main processes of decomp

Answer 10

1. Autolysis/”self digestion”

2. Putrefaction

Question 11

Autolysis

Answer 11

• > destruction of cells through the action of their own enzymes

Question 12

putrefaction

Answer 12

• > microbial deterioration of tissues due to the proliferation of bacteria in the digestive tract
• > can cause colour marbling, bloating from subcutaneous gas accumulation, skin slippage from deterioration of connective tissue between the dermis and epidermis

Question 13

list all the stages of decomposition

Answer 13

1. Fresh
2. Bloat
3. Active decay
4. Advanced decay
5. Skeletal/dry remains

Question 14

fresh state of decomp

Answer 14

• > period from death until first signs of bloating
• > decrease in body temp
• > lack of odour
• > the stage ends with the arrival of blow flies and laying of eggs

Question 15

bloat stage of decomp

Answer 15

• > gas accumulation with distended abdomen
• > discolouration, strong odour
• > this stage ends with the development of the maggot mass

Question 16

active decay stage of decomp

Answer 16

• > sizeable maggot masses, strong odour and greasy appearance of soft tissue
• > this stage terminates with the collapse of the thorax

Question 17

advanced decay stage of decomp

Answer 17

• > disappearance of maggot masses, decrease in body mass
• > soft tissue changes are extensive
• > this stage ends with the disappearance of beetles and non desiccated/mummified soft tissue

Question 18

skeletal/dry remains stage of decomp

Answer 18

• > terminal stage
• > only bones, cartilage and desiccated soft tissue remain
• > no odour or insect activity
• > depending on environmental conditions, a body can remain in this stage indefinitely

Question 19

factors that affect decomp

Answer 19

• > insects
• > animal scavenging
• > plants
• > soil acidity
• > climate
• > sun
• > water
• > decomp context
• > temp

Question 20

forensic entomology

Answer 20

the study of arthropods - scavenging insects, arachnids, centipedes, millipedes and crustaceans associated with forensic context

Question 21

when is insect activity the most useful to determine TOD

Answer 21

in early stages of decomp

- > i.e. blowflies are the first to arrive, then maggots then dermestid beetles

Question 22

animal scavenging

Answer 22

the consumption and associated modification of remains by other animals which can lead to disarticulation

Question 23

stages of animal scavenging

Answer 23

0. Minor scavenging
1. Thorax destruction and disarticulation of upper extremities (scapula, clavicle, arms)
2. Removal of lower extremities
3. All skeletal elements are disarticulated EXCEPT vertebral column
4. Total disarticulation

Question 24

signs of carnivorous animal scavenging

Answer 24

Puncture wounds
- > areas of bone that have collapsed under the force of carnivore tooth pressure, most diagnostics, small perforations
Pits
- > similar to punctures, except they fail to penetrate through the cortical surface of the bone
Scoring
- > linear grooves across the cortical surface of the bone, usually occurs as a group or parallel lines
Furrows
- > similar to scoring, except deeper and usually towards the ends of bones

Question 25

forensic botany

Answer 25

the discipline concerned with the medical-legal impact of plants found in association with human remains - > the amount of plant growth in and around human remains can help provide a PMI

Question 26

roots effects of remains

Answer 26

roots have been found responsible for the articulation, as well as damage, of remains

Question 27

soil acidity and its affect of decomp

Answer 27

- > as soil pH decreases, the rate of decompt increases - > most healthy soils range between 4-8 - > the majority of bacteria function best at a pH of 6, furthering decomp - > however, the more acidic the soil, the less functional microbial bacteria is - > at extremely low pH levels, soil fungi becomes dominant

Question 28

peat bogs

Answer 28

acidic water, low temps and lack of oxygen are excellent preservation tools

Question 29

hot vs cold climate's affect on decomp

Answer 29

- > warmer and more humid areas encourage insect activity, speeding up decomp. * even small fluctuations like shade vs sun can affect decomp - > decomp slows in colder climates, insect and bacterial activity is less common

Question 30

suns effects on decomp

Answer 30

- > sunlight is the most destructive process to bone - > similar to fire, the heat of the sun causes bones to shrink as water is removed - > brittle and fragile - > flaking and cracking will occur

Question 31

waters effects on decomp

Answer 31

water causes body fat to rehydrate, resulting in adipocere

Question 32

adipocere

Answer 32

"corpse wax" - > hydrated fat that can help preserve forensic evidence - > can begin forming within hours of death, but usually takes weeks

Question 33

fluvial transport

Answer 33

the movement of skeletal remains in aquatic environments | - > can be affected by currents, body weight, temp, horizontal velocity of water, gases in tissues

Question 34

temperatures affect on decomp

Answer 34

- > primary determinant of soft tissue decomp - > accounts for more than 80% of soft tissue decomp variation - > decomp depends brimarily on bacterial proliferation and insect development, which are HIGHLY dependant on temp - > PMI calculated from understanding of temperature in depositional environment

Question 35

ADD

Answer 35

Accumulated Degree Days - > sum of average daily temperatures for a given number of days, in relation to a temperature threshold ADD= 10^(0.002*TBS*TBS+1.81) +/-388.16 KNOW HOW TO DO THIS FOR FINAL

Question 36

TBS

Answer 36

Total Body Score | - > decomp score for separate regions of the body (trunk, head/neck, limbs; Table 5.4-5.6)