How is Forensic Taphonomy Useful in Investigations?
Forensic taphonomy is the post-mortem transformations or changes that occur in the dead remains of a corpse since the death and its discovery. The word Taphonomy is derived from the Greek words- ‘taphos’ which means “burial“, and ‘nomos’ which means ‘law“.
The term taphonomy was first defined by Russian geologist Efremov(1940) to encompass studies in what he referred to as the “transition of animal remains from the biosphere into the lithosphere”. The use of taphonomy in forensics was first described by Dirkmaat and colleagues (2008) as “the most significant development to alter the field of forensic anthropology.”
What is Forensic Taphonomy?
Forensic taphonomy involves the investigation of soft tissue changes, decomposition rates and patterns, the dispersion of body parts, and the modifications that occur to both soft tissues and bones.
The effect of the environment on the decomposition of a dead corpse is an important factor. As per Casper’s dictum, a body decomposes in the air twice as rapidly as in water and eight times as rapidly as in earth.
Forensic taphonomy focuses on the perimortem (at the time of death) and intermediate postmortem (days to weeks after death) biological and biochemical transformations in order to determine the cause of death, estimate the approximate time of death, and identify human remains including the sex, age, race, and, whenever possible, the individual’s identity.
As earlier discussed, taphonomy is the time interval between the death and discovery of the corpse, so the various changes that occur during this interval give a lot of information about the time since death.
Broadly the taphonomic studies are conducted in three stages:
- Necrology: These are the factors present at the time of death such as skull fractures, marks of fangs or claws in bones, signs of malnutrition, infections, lesions by blunt instruments, bullets, etc.
- Biostratinomy: These are the factors affecting the decomposition of the dead corpse such as the environment where remains were found.
- Diagenesis: The process of lithification or compaction of the sediments that envelop the remains, ultimately resulting in fossilized bones.
Stages of Taphonomy
The taphonomic study involves the observation of various changes occurring in the dead corpse, which can be classified into five stages:
- Disarticulation– In this stage the flesh is fully separated from the corpse and only the skeleton remains.
- Dispersal– It is caused due to the effect of natural factors like floods or scavengers, which leads to the detachment of the pieces from the whole skeletal frame.
- Accumulation– This is the stage when there is a build-up of inorganic or organic materials on the skeleton by biogenic processes.
- Fossilization– After the skeletal remains get buried in the soil, there is a flow of mineral rich groundwater that fills the gaps in the skeleton and forms a fossil for that skeleton.
- Mechanical Alteration– This is the last stage of the taphonomic changes which means the physical alteration of the skeleton or skeletal remains.
Classification of Taphonomy
The skeletons are easier to recover from the ground if they are complete and in good condition but this is not always the case. The condition of the skeleton when found is dependent on a number of factors.
Based on these factors taphonomy can be classified as Geotaphonomy and Biotaphonomy.
Geotaphonomy refers to the study of the geological and botanical environment of the area where the body was buried. The type of soil, depth of the grave, disruption of vegetative growth, water movement, erosion pattern pH of the soil, etc. are some of the factors that are affected by the buried corpse and simultaneously they affect the decomposition of the corpse.
Biotaphonomy examines the corporal remains for enquiring about the process of decomposition of soft and hard tissues. The decomposition of the corpse is dependent on the climate, scavengers, person’s health, age, pathology, and cultural factors such as autopsy methods or mortuary practices, etc.
Difference Between Taphonomy and Post-Mortem Interval
Post-mortem interval is the time since death or estimating the time that has elapsed since physiological death and medicolegal examination whereas taphonomy can be considered as the post-burial time which means the amount of time that has passed since the burial of remains until their retrieval.
The post-burial interval can reveal whether the dead body was originally buried at the place where it was recovered or it is the secondary burial site. It can also tell that the body was immediately buried after death or after some time.
After the death, post-mortem changes start after 2-3 hours. These include pallor Mortis (pale coloration of the skin), algor mortis (cooling of the body), livor mortis (discoloration of the dependent body parts), rigor Mortis (stiffening of the muscles).
The inhabitation of insects on the dead corpse is also an important factor for determining the postmortem interval.
Post burial interval of the dead can be determined by the various stages discussed above in this article. It is a very tough job as not always a full skeleton is recovered from the scene and a lot of knowledge from different disciplines is required for the study.
Forensic taphonomy is a pretty new field of study that is in its growth stage. A lot of research has been conducted in the field and a lot of techniques and tools have been developed to perform taphonomic studies. Still, there are certain loopholes and gaps in this field which are barriers to the successful execution of the processes.