Decomposition Flashcards
What is decomposition?
Decaying caused by bacteria or fungal action
A continual process that can take weeks to years, depending on the environment and is necessary for all life on earth.
What is taphonomy?
Study of burial and everything surrounding it
It involves the transition of living organisms from the biosphere to the lithosphere.
What is a necrobiome?
The microbiome of bacteria present in the body after death
It becomes influenced by its environment and also influences its environment.
What is the significance of vegetation in decomposition?
Differential plant growth can be visible for years, aiding in the identification of mass graves
Some species, like wormwood in the Balkans, can serve as markers.
What does forensic taphonomy study?
The fate of human remains in relation to criminal law
It includes PMI estimation, timelines of events, and the investigation of cadavers.
What are the traditional stages of decomposition?
- Fresh
- Bloat
- Active decay
- Advanced decay
- Skeletonisation
Research may propose different categorizations.
What regulates decomposition?
Resource quality, decomposer community, and physiochemical environment
Factors include body mass, temperature, and oxygen levels.
What is autolysis?
The breakdown of cells within the body due to self-digestion
It is followed by putrefaction and is a primary driver of decomposition.
What is PMI estimation?
Time since death estimation
It relies on evidence from the body, environment, and daily activities.
Why is PMI important?
It impacts legal questions regarding alibi, opportunity, and cause of death
It helps implicate or eliminate suspects.
What are the two types of PMI estimation methods?
- Rate method
- Occurrence method
The rate method is generally considered more reliable.
What is rigor mortis?
The stiffening of muscles after death
It begins within 3-6 hours of death and resolves within 36 hours.
What is livor mortis?
The pooling of blood due to gravity after death
It typically appears within 30 minutes to 1 hour after death.
What does the fresh stage of decomposition involve?
Paling of skin, relaxation of muscles, and changes in body temperature
Autolysis is the primary driver during this stage.
What occurs during the bloat stage?
Gas buildup causes distension, leading to greenish discoloration
This stage is driven by bacterial action.
What characterizes the active decay stage?
Maggots hatch and destroy the integrity of the body
Bacterial action continues, and gases are released.
What happens during advanced decay?
Drying out of remains and retreat of maggots
Insect activity shifts from maggots to beetles.
What is skeletonisation?
The gradual exposure of bones as decomposition slows down
It becomes harder to estimate PMI at this stage.
What are extrinsic factors that affect decomposition?
- Temperature
- Access by insects
- Moisture/humidity
- Sun/shade
- Burial environment
Each factor influences the rate and process of decomposition.
What are intrinsic factors affecting decomposition?
- Body size
- Surface area to volume ratio
- Fat content
These factors influence how quickly a body decomposes.
What is cadaveric spasm?
Immediate muscle stiffening in response to high tension
It differs from rigor mortis and can occur in situations like drowning or violent homicide.
What is the role of scavengers in decomposition?
They contribute to mechanical breakdown of remains
Different populations of scavengers exist based on geographical location.
What is desiccation in the context of decomposition?
Browning of the skin due to drying exposure to heat or air
It leads to differential decomposition rates.
What is desiccation in the context of decomposition?
Browning of the skin/membrane due to drying/exposure to heat or air
What happens to hair and nails during desiccation?
Skin retreats; hair and nails do not grow
Which body parts experience desiccation first?
Extremities
What is Tache noir?
Drying of the eyes due to being left open after death
What intrinsic factors influence decomposition?
- Body size
- Surface area to volume ratio
How does surface area to volume ratio affect mummification?
Large S.A to volume ratio leads to mummification; small S.A to volume ratio results in faster decomposition
How does fat affect decomposition?
Fat can act as waterproofing, preventing moisture loss
Why do very thin people decompose slower?
They are more likely to desiccate/mummify
How do clothing and coverings affect decomposition?
- Prevent access and exclude oxygen
- Can act as insulation
- Depends on material (synthetic vs. natural, absorbency, weave)
How do wounds influence decomposition?
Wounds allow entry of air and insects, speeding up decomposition
What effect does severe blood loss have on decomposition?
It can starve decomposition bacteria of food and slow bacterial colonization
What is the effect of burning on decomposition?
- Sterilizes skin surface
- Destroys skin and allows access to internal tissues
- Reduces likelihood of insect oviposition
How can disease impact the rate of decomposition?
- Septicaemia accelerates decomposition
- Anaemia slows decomposition
- Fever can accelerate decomposition
What role do drugs play in decomposition?
- Certain drugs affect decomposition rate
- Influence insect activity
- Can raise body temperature at time of death
What is differential decomposition?
Body parts decompose at different rates influenced by the deposition environment
What is Total Body Score (TBS)?
A visual scoring method to record taphonomic changes by scoring head, torso, and limbs
What is the range of Total Body Score (TBS)?
Min score = 3 (fresh), Max score = 35 (skeletonised)
What are some challenges in using Total Body Score?
- Subjective scoring
- Intra/inter observer bias
- Needs adaptation for water environments
What are other methods used in decomposition studies?
- Entomological
- Microbial
- Forensic botany
- Forensic geology, pedology, geoscience
What does entomology study in the context of decomposition?
- Insects attending the body
- Species identification
- Life cycles and development
What is the necrobiome?
The microbiome of the body after death
How do volatile organic compounds (VOC) assist in forensic investigations?
- Detection dogs locate bodies
- Characterization and concentration for PMI estimation
What does forensic botany study?
- Flowering period/seasonality
- Growth rate of plants, algae, lichen
- Disturbed growth/regrowth
What is bone diagenesis?
Bone degradation influenced by weathering, color changes, cracks, and fractures
