Lecture 9 - Forensic Anthropology and Taphonomy Flashcards
stages of decomposition in order
fresh bloat active decay advanced decay skeletonised
Fresh
From the moment of death to the onset of bloating (This is where rigor mortis > livor mortis > algor mortis happens)
Body produces gases, autolysis (body eats itself and produces gases, body is broken down by its enzymes) and putreification occurs
Three things that happen in fresh stage of decomposition
Rigor mortis
livor mortis
then algor mortis
rigor mortis
stiffening of the muscles
livor mortis
colour change due to the gravitational pooling of blood
algor mortis
temperature change
Bloat stage
Epidermis slips off, hair will loosen and slip off with skin, abdominal discolouration
Distension of the abdomen
Discolouration/marbling, green like discolouration underneath the skin
Sometimes the skin slips off
Hair shrivels and shrinks back, tissues become detached from each other (hair and nails do not keep growing after death)
Active decay stage
Active decay - Tissues and organs soften and degenerate then liquefy, foul odour, and body eventually collapses
Bursting of the abdominal cavity
Decomposing liquefaction occurring in abdomen from the gut bacteria explodes and surrounds other tissues, get smell of death in this phase (very stinky)
No structure to hold body together anymore so the body collapses
Body tissues liquify and purge out
Advanced decay stage
Advanced decay - Remaining flesh desiccates and shrinks, surface tissue assumes leathery texture, and less pungent odour
Less smelly
Skin can start to dry up and mummify
Skeletonised stage
Skeletonised - Dry body now decays very slowly, and may become completely skeletonised
All soft tissue has decomposed so only have bones and teeth
Skeletonisation is the stage that the forensic anthropologist deals with, in these situations they can also be dealing with mummified tissue and hair
body goes through autolysis where
the body is broken down by its own enzymes i.e. the body is eating itself
when you have animal activity going on around the remains then you
have much more accelerated rate of decomposition
Primary level of human identification
1- fingerprints
2- dental
3- DNA
Secondary level of human identification
Anthropology/disease/injury/scars/unique tattoos
If you have an unknown skeleton found then can use anthropology to look at diseases and injuries and to provide a basic biological profile of what the bones can tell us
If there was soft tissue remaining or mummified tissue present then may use scars or unique tattoos to help identify the person
Although anthropology is not up their as a primary method of identification it is still very useful as a secondary method to help narrow down the search to narrow down you might be searching dental records for or looking at the missing persons list for
tertiary level of human identification
unique clothing, jewellery
circumstantial level of human identification
documentation, face, generic tattoos, clothing, jewellery
Forensic agencies involved in fresh stage
forensic pathologist, fingerprint expert, DNA analyst, odontology
Forensic agencies involved in bloat stage
forensic pathologist, fingerprint expert, DNA analyst, odontology
Forensic agencies involved in active decay stage
fingerprint expert, DNA analyst, odontology
Forensic agencies involved in advanced decay stage
fingerprint expert, DNA analyst, odontology
Forensic agencies involved in skeletonised stage
forensic anthropologist, odontologist, DNA?
Skeletonisation …
Refers to the completion of soft tissue decomposition, where only the hard tissues of the skeleton remain
Skeleton includes the bones and the teeth (dentition)
In many forensic cases there is still mummified soft tissue present on the skeleton (it is never totally clean usually) and in some circumstances you need to remove it before examination
The skeleton itself can also undergo postmortem changes =
taphonomy
forensic anthropology and the skeleton
Our skeleton tells a story about the evolution of our species and of life (and death)…
Forensic anthropologist used in these examples of mass disasters
Look at skeleton
In a forensic context looking at the circumstances of death
Everything about you is etched in your bones such as your childhood, how healthy you were, how well you grew, did you have any illnesses when you were a kid, nutritional status, family of origin, where you drank your water from as a kid and was it different from when you were an adult etc etc
Your skeleton tells a story of your life, in a forensic setting your skeleton tells you a more of a story of death or the circumstances of your death
Need to do your best for the deceased and for the families
The anthropological protocol
Is it bone? Human? Forensic context? How many individuals? Biological profile = sex, age at death, ancestry, stature trauma and pathology identifying characteristics
Human vs non-human (other animal)
Look at two main features = maturity and architecture
human vs non-human - maturity
Forensic anthropologists need to know about the human skeleton and how it develops and how children’s skeletons developments
Growth and development
Unfused epiphyses and other structures
Example of the human pelvis and knowing maturity …. For adults their are two os coxae and one sacrum that make up the pelvis whereas a neonatal (brown bones on image) version is 3 bones rather than one bone and as you get older, your bones grow within themselves at their own growth plates and then when you reach the age of maturity which is different for individuals based on family, lifestyle, sex and other factors your bones will actually fuse together and the cartilaginous growth plates that are in between the two aspects of bone will disappear and then you stop growing so this is one way that we age and even though it is different for each individual it is still following a set pattern
human vs non-human - architecture
Architecture - when we come to think of humans as a species is the shape of our bones and our architecture
Shape differences
Biped vs quadruped
Humans are habitually bipedal therefore our bones are a certain way and are identifiable by this, makes our bones very unique to us
Muscle rugosity
Components of the biological profile
sex age ancestry stature (height) Trauma and pathology Identifying characteristics
Sex differences in the pelvis
Female features Greater than 90 degrees angle at the subpubic angle *** Sacrum tilted back Flared ilia Male features Less than 90 degrees angle at the subpubic angle *** Sacrum tilted forward Narrow ilia
The pelvis is an evolutionary difference that is there no matter your ancestry
What is the sex (not gender)?
Try look at pelvis before skull
All the differences in skulls between sexes due to muscle mass
Males have lerger muscle attachments, but not a fixed rule i.e. men can have more gracile skulls
Age estimation in children ….
Children: Based on maturity and fusion of bones.
Look at the diaphysis (long bit) and epiphyses (ends of the bone) and they have ossification centres in the middle of them so this is where the cartilage starts to ossify and then get bigger and longer and then due to your genetics and your environment you will at some point stop growing
Have ossifications centres in the middle of the bones **
age estimation in adults …
Adults: Based on degradation of surfaces.
subadult age estimation …
~450 ossification centers at birth
450 tiny little bits of bones that eventually fuse and form into 206 adult bones
Eventually fuse to become 206 bones in adulthood
Track ossification center development and fusion for aging.
Tracking means you can help to determine age
age estimation and the skull
Skull is a number of different bones when you are growing, also have cartilaginous structures in between the bone which will allow the expansion and growth of the skull and then eventually when you stop growing the bones will knit together at places called suture margins but even as a 25 to 27 year old you can still have one particular suture that is unfused which is right in the middlel
subadult aging and dental
Dental eruption and development
Both forensic odontologists and forensic anthropologists should know eruption and development patterns of children
Relatively stable and accurate
pubic symphysis
front of the pelvis
Has wad of cartilage in between it
Wears away over time, degrades overtime to a point where the bone starts wearing away, over time you have some changes which start off nice and billowy which then starts degrading and producing a smooth surface and then the cartilage is essentially gone and starts sweating away even more, these changes are quite well documented although they do not give you an exact age and instead give you an age range that the pelvic human remains could belong
Then as adults you have degenerative patterns
Cant give you a specific age but can give you an age range
Ancestry (not ethnicity)
eye orbits change shape
Nose change shape in skull
Can see soft tissue changes between ancestry groups and these are affected in your bones as well
Polynesian remains - rocker jaw, jaw has a rounded corner will rock on a table (not always true), European jaw will not rock on the table, not always true because we have very diverse and mixed ancestry groups
skeletal trauma analysis
Timing of trauma
(ante-, peri-, postmortem)
Force that caused trauma
(blunt, sharp, projectile, misc.)
Number of wounds
Sequence of wounds
Placement of wounds
Can start to rebuild the circumstances/story of what happened around the time of death
Main concerns for a forensic anthropologist
The recovery and analysis of skeletonised humans for law enforcement agencies.
The identification of victims, perimortem trauma, and postmortem disturbance for presentation in court.
Want to identify the trauma so that it can be used in the legal proceedings
Antemortem pathology – victim identification; evidence of disease and trauma before death.
Perimortem trauma – evidence of trauma around the time of death “manner of death”
Postmortem trauma – disturbance after death
Taphonomy – plants, animals, insects, or other natural forces that explain position/condition of body
Antemortem pathology
Antemortem pathology – victim identification; evidence of disease and trauma before death.
Perimortem trauma
Perimortem trauma – evidence of trauma around the time of death “manner of death”
Postmortem trauma
Postmortem trauma – disturbance after death
Taphonomy and forensic anthropology
Taphonomy – plants, animals, insects, or other natural forces that explain position/condition of body
Forensic anthropologists and crime scene search/recovery
Assist law enforcement in the search and recovery of human remains
Certain sequence of events in the decomposition of bodies so forensic anthropologists can help especially since they know hallmarks for the different stages that you can look out for
Death in water presents with the body in a very specific face down and limbs hanging down limply in the water
Can look at ground differences, usually a forensic archeologist doing this
Surface scatter
missing persons are most likely to be found above ground decomposition with surface scatter, they are not buried and so their body/body parts are found on the surface and will be found disarticulating on the surface
Skull acts like a ball when it becomes detached from the jaw, rolls to any contour
The mandible and spine are not very movement orientate shapes so usually remain where the body was first positioned/where the person became deceased
Legs and arms may be taken away by scavengers so may be further away from the rest of the body
These are all clues that can be looked at to identify the circumstances around the death
burial excavations - cold cases
Re-exhume someone or further evidence has come up or clandestine burial (unmarked grave) and you need to remove that body from that location are scenarios where forensic anthropologists can be involved in burial excavations
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What is forensic taphonomy?
“Forensic taphonomy is the study of the postmortem changes to human remains, focusing largely on environmental effects—including decomposition in soil and water and interaction with plants, insects, and ” other animals.
Three factors of taphonomy
The grave (environmental factors) The soil type and pH, vegetation, near water or not etc can affect the bodies
The assailant (behavioural factors)
Was it a quick dug grave? Was it preplanned? Was the grave deep?
Can discuss the behaviour of the assailant
If it is a homicidal investigation, can judge the character of the person from various cues
The remains (individual factors)
Differences of being human
e.g. all have different microbiomes which can affect decomposition
taphonomic factors that will influence the remains when they are found
buried, concealed or burnt
- soil pH, texture and moisture
Method (i.e. wrappings/clothes, coffin, lime, mass burial)
Scavenging activity – trauma?
protecting body from scavengers by covering them slows down decomposition whereas exposed remains are more likely to have fastened decomposition due to scavengers having access to the remains
Climate (Incl. soil, water or air temp)
Microorganisms
Insect activity
Above ground decomposition
Major factor that influences the body is the climate
Temperature is one of the most influential factors
When the body is above the ground and decomposition the biggest influence on the rate of decomposition is the climate/temperature
Warm temperatures increase rate of decomposition
the body will skeletonise faster
Associated with an increase in biological activity
Precipitation
if it is raining the flies are not going to be out
Humidity
Sun/shade
savengers may not want to be in the direct sunlight
Wind
All of these will affect the decomposition rate, also affects scavengers which again influences the decomposition rate
Summer decomposition of pig
Two very different environments
Sydney one was in blue mountains and at a change on altitude and the humidity was so dry that it meant that the pig decomposition was affected, so the pig mummified the body since it all got dried out
decomposition is faster for both because of the summer climate and environmental features of that time of year
winter decomposition of pig
takes longer for decomposition
Forensic implications of climate
Insect activity will accelerate decomposition
Forensic entomology used to estimate time since death
Insect colonization and succession
Decomposition rate varies when insects are restricted
forensic implications of scavengers
Scavengers will influence decomposition rates
Scavengers can affect estimation of time since death
Dispersal of skeletal elements may hinder locating decomposed remains
less of an affect in NZ
can affect evidence and leave their own evidence, called postmortem trauma and it looks different to trauma that occurred around the time of death
Burial as a body disposal method
Less insects
as you go deeper down
Less scavengers
Deeper burial = slower decomposition
Shallower burials = ambient temperature
Also coffin/wrapping will stop any interaction with the surrounding burial environment and the body so you might get a lot of adipocere forming to protect the body
Moisture and soil texture
Sandy Soils drain moisture
Clay soils retain moisture
Adipocere formation
body fat hydrolysis, act as a waxy fatty layer and protects skeleton and can even protect soft body tissues even the soft tissues
adipocere formation
An exposed, insect-infested body or a body in a warm environment is unlikely to form deposits of adipocere.
Wrappings and body disposal
Look the vegetation because plastic stops the nutrients seeping
Uncovered would provide increase in vegetations
cloth wrapping
Inhibits decomposition
Prevents access to microorganisms
May promote adipocere formation
in this case, good wrapping can slow down and event halt decomposition i.e. can preserve the body so may even have fingerprints, facial recognition etc.
lime
Restricts microbial activity
stopping microbial activity = stops decomposition
Highly alkaline pH
Slows decomposition and can cause preservation
can cause preservation of soft tissue
Fire damage is
Forte of the forensic anthropologist because all the soft tissue has been removed
pugilistic posture
pugilistic posture
flexion of all major muscle groups
Occurs when the body is fresh
If body already dead before fire, rigor mortis occurred then this posture does not occur ***
The main thing being investigated is whether the fire caused the death or whether the fire was used to cover up the death
Burn pattern to do with flexion, red bits get burned first, blue bits on the image are protected due to the position
