ARCL 228 -whats happening after death??

Taphonomy

Study of everything that occurs to body/biological being after death until discovery

• natural process the affects the disarticulation, preservation and movement of the skeleton

• Taphonomic changes can affect the position of skeletal remains which could make it more difficult to reassemble to remains or estimate identity and cause of death

Taphonomic process

• movement of remains from biosphere (all living things) to Lithosphere (all non-living things)

• Decomposition (soft tissue decomposition)→ biostratinomy (disarticulation, fragmentation, abrasion, bioerosion) → diagenesis (dissolution, compaction, early and late mineralization)

Forensic taphonomy

Study of post-mortem processes which affect state of preservation and recovery of human remains

• want to be able to discover how person died/the damage

• Can help reconstruct the circumstances surrounding a death event

Mortem terms

Antemortem: occurring before death

Perimortem: occurring during/near death (trauma/defensive wounds)

Postmortem: occurring after death

Postmortem interval: time since death after discovery

• forensic anthropology mostly handles after years unless cases like burning

How do we know about taphonomy

1. Studies of animal/human decomposition (environment very important with decomposition → humidity/moisture)

2. University of tennessees Anthropological research facility

3. Venus (under water studies)

What happens to a body after death? - routes

1. Death → Putrefaction/autolysis = normal decomposition → after soft tissue decomposition = skeletonization → animal predation

2. Death → saponification (large portion of body becomes waxy) → animal predation → skeletonization → animal predation

3. Death → mummification → animal predation → skeletonization → animal predation

4. Death → burning

All end in diagenesis

What happens during decomposition

Biochemical/physical changes that happen to body after death leading to skeletonization

• organic material is broken down into simpler forms immediately following death

• Can distort to position of the body, or create artifacts in the position

• Occurs before of 2 chemical and microbial processes

1. Autolysis: destruction of cells/organs by aspect chemical processes

2. Putrefaction: destruction of tissue by bacteria/fungus in intestines or from outside body

What can affect the timing of decomposition

Intrinsic Factors

• body size, pathology, trauma etc → eyes/mouth holes allow microbes to enter and speed up decomposition

Extrinsic factors

• burial environment, temperature, humidity, scavengers etc

What 3 steps take remains from biosphere to the lithosphere

1. Decomposition

2. Biostratinomy

3. Diagenesis

What is post-mortem interval

Time since death

What are the two breakdown processes involved in decomposition

Autolysis and putrefaction

What happens to body following death (Mortis)

Death occurs when heart stops beating

Decomposition begins immediately after death

Changes to soft tissue occur very quickly (minimutes after death occurs)

1. Pallor mortis

2. Algor mortis

3. Livor mortis

4. Rigor mortis

Often the stages that are examined by death investigators → coroners/medical examiners

Autolysis/putrefaction = decomp processes

Stage 1: Pallor Mortis

As heart stops pumping blood, body takes white/grey appearance

Occurs immediately after death

Result of somatic cell death

Stage 2: Algor Morris

The cooling of the body after death, as temp of body is no longer regulated by body and changes to approximate surrounding environment

Body cools at rate of 0.8 degrees per hour

Can help establish the time of death

Stage 3: Livor Mortis

Also referred to as lividity/hypostasis

• purplish/red discolouration → gradual pooling of blood in places closer to the ground

• Most pronounced at 12 hours after death

2 types of Livor Mortis

1. Non-fixed = 30 mins-4 hours after death

• blood pools in new locations where gravity pulls to the ground

2. Fixed = 4 - 8 hours after death

• Pooled blood/red colour no longer disappears with pressure/moves

• As body cools, fat surrounding capillaries solidifies constricting capillaries and prevents movement of blood to other areas of body

Stage 4: Rigor Mortis

Begins immediately after death, but not detectable until 8-12 hours after

• stiffening of muscles due to chemical changes in muscle tissues

• As cells run out of oxygen calcium builds up in tissue, ATP production ends, causing contraction of muscle fibres

After 12 hour mark, decomposition will continue in the muscles and rigor will begin to pass

• if rigor looks to defy gravity or is not consistent with the position of the body, it indicates that the body has been moved

Stage 5: Autolysis

Begins immediately after death

• autolysis: degeneration of body tissue by digestion fluids from intestines

• Post mortem chemical fermentation process → involves no bacteria

Enzymes in pancreas/stomach are no longer regulated by the body, they begin to digest cells as if they were food causing general destruction of internal organs

Intravascular Hemolysis: Digestive enzymes/bacteria increase circulatory system → darkening of blood vessels

Stage 6: Putrefaction

Putrefaction: uncontrolled growth of endogenous bacteria

• as autolysis breaks down tissues fats, carbs and proteins are released (which fuels putrefaction)

• The two processes generally occur simultaneously

  • Green discolouration can occur early in the lower abdominal area over cecum due to the formation of self hemoglobin

Intravascular hemolysis, skin slippage and bloat are driven by putrefaction and autolysis

• bacterial digestion creates gasses which causes bloating of the internal/external tissues, primarily in the abdomen

• Skin slippage will also begin to occur as the epidermis is spread

Skeletonization

Soft tissue decompression is complete and only hard tissue remains

• bone is exposed

• Tendons, ligaments and or cartilage may still be intact

Timing depends on different internal/external factors

• environmental conditions like temperature, moisture, soil chemistry, body coverings, scavenger, exposure to physical or chemical agents

• internal conditions like activity, internal composition, chemical embalming agents, injury

Saponification

Portions of Body can be saponified → not whole body must be affected

• in hypoxic, moist or alkaline conditions the fat tissue of the body can undergo a chemical change to become adipocere

  • Adipocere: a yellow-grey/white, waxy substance that preserves the soft tissue contours of the body

• Can occur between 3 weeks/2 months after death

Mummification

Preservation of remains by desiccation or drying out

• occurs under dry/low humidity conditions (either hot/cold)

• The skull will turn yellow-brown → black and become leathery

• Can also occur due to tannic acids present in peat bogs

What is this?

Mummification

What is this?

Saponification

What stage is this?

Stage 4: rigor mortis

What stage is this?

Stage 3: livor mortis

What stage is this?

Stage 2: livor mortis

Postmortem bone change → after skeletonization

Once soft tissue has decomposed the remains will enter a state of advanced decay

• This is when we see changes impact the bone

  • The continued modification and degradation of the skeleton will largely depend on dispositional environment

Biostratinomy and diagenesis

Both of these terms deal with the chemical, physical, biological changes to the skeleton postmortem

• biostratinomy: pre-burial skeletal modification effecting organic components

• Diagenesis: anything that happens to skeleton postmortem

  • Post-burial medications, effecting inorganic components ending in fossilization

Factors that effect post-mortem skeletal changes

1. Weathering

2. Bioturbation

3. Plant damage

4. Burning

5. Cut marks and fractures

6. Staining

7. Animal damage

Weathering

Decomposition of hard tissue as response to natural agents in environment overtime

• separation of the organic/inorganic elements of the bone → makes bones much more brittle/fragile

• Factors contributing to weathering

  • Sun exposure

  • Wet/dry cycles

  • freeze/thaw cycle

  • Done density

  • Genus/species

What effect on the bone is this?

Weathering

• Bleaching

• Cracking

• Flacking

• Warping

• Erosion

Bioturbation

Disturbance of sediments by living organisms

• caused by burrowing animals, like earthworms, rodents, rabbits, weasels, moles etc → can be harmful when trying to determine the cause of death

Plant damage

Roots searching for water and nutrients secrete acid in order to break up soil → can etch surface of buried bones

• lines look vainy/root patterns → can be confused with actual cut marks

Larger roots can cause disarticulation

• can look like cut marks

What effect on the bone is this

Plant damage

• roots

Burning

When cremation/burning occurs this will char/burn bone

• level of char is impacted by fleshed or de-fleshed bone/temperature of fire/duration of burning

Cut marks

Incisions or cuts → V/U shaped marks in cross sections

• chopping or hacking marks

• In forensic scenarios often the result of peri or postmortem trauma

Fractures

• Has perimortem and postmortem trauma (living/dead bone)

• both wouldn’t heal because trauma occurs when person has already died → postmortem would affect skeleton differently

Staining

Bone staining from soil/environemnt around body → discolouration from sediments are transported via groundwater into bone pores

• staining can also occur via prolonged contact with

  • Fluids

  • Leaves

  • Algae

  • Metal objects

Scavenging

Can affect the rate of decomp of soft tissue/post-mortem

• scavenging: consumption and association modification of set of remains by animals

• Important to understand animal modification and distrurbance when studying remains

• Different species will follow a succession when colonizing or scavenging remains

Insect scavenging

If insects are present in the environment, they will be the first scavengers to arrive to body

• forensic entomologists attempt to use incest activity to estimate the PMI from soft tissue in early decomposition

• Many factors will influence how quickly insects arrive

  • Seasonality

  • Movement of remains

  • Trauma

  • The presence of drugs

Insect scavenging: flies

Blow flies/house flies/flesh flies arrive at a body and deposit their eggs/maggots within minutes to hours after death

• don’t generally modify bone

• Stage of development the larvae are in helps determine to PMI

Omnivore and carnivore Scavenging

Scavengers will consume both soft and hard tissue, as well as modify, disarticulate and disperse both soft tissue and bone

• canines like wolves, dogs and foxes

Aquatic scavengers

Sharks and other fish will go for soft tissue like the skin

• crustaceans will tear away muscle

• Other species included = endoderms, mollusks, beach flies etc

Estimating PMI

When calculating you need

• TBS = sum of decomposition scores

• ADD = sum of average daily temperature for a given amount of days (doesn’t work if consistently under zero)

This gives us the PMI = accumulated degrees of days since death

PMI calculations

1. Score body decomposition (with charts)

   1. Sum of the score = TBS

2. Plug TBS to formula given

   1. This gives us the ADD

3. Divide by average temperature

The number gives us # of days body has been exposed (round to closest whole number)