“Unfortunately, the clock is ticking, the hours are going by. The past increases, the future recedes. Possibilities decreasing, regrets mounting.” _ Haruki Murakami, Dance, Dance, Dance
An essential reason for why we investigate an event is because it occurred in the past. Otherwise, one can simply record it happening and that could be the end of all inquiries. Past events, current investigations and preventions for the future are only few notions that show how important time is in forensic science. The holistic approach towards the subject was initiated by professionals at the beginning of the century. Professor Pierre Margot describes time as a limited ressource that marks every reality while being itself a perception in every reality (P. Margot, A Question of Time, 2000).
One way of expressing time is through chronology. Here we visualize it with a timeline carrying a succession of happenings:
One major characteristic of time is its unidirectionality. Unlike the three dimensional space where a return to square zero is always an option, reverting back in time is practically impossible (at least today). Whatever happened has happened and becomes automatically out of human control.
Shown in the timeline above is an interesting interval labelled (tx-t0) that shall bring our attention:
All physical evidence that is transferred (at t0) can be subject to disruption and degradation up until it is collected and safely preserved by specialists (at tx). It is during this critical timespan that irreversible loss of information often occurs dramatically.
This amount of time it takes to secure the evidence against further degradation can vary so tremendously between different materials and environments, that the overlap between the forensic scientist and the archaeologist is unavoidable: They are both on an assignment to reconstruct a past event. It could have happened this morning, and it could have happened 3000 years ago.
To better illustrate the diversity and unicity of the evidence and its evolution, take as an extreme example the difference in the decomposition rates of a latent fingerprint that was left on a surface laying outside, and a human body that was buried in a soil allowing the decomposition of the soft tissues (fat, organs, nerves, muscles, joints and blood vessels). Not only it is expected that the fingerprint will disappear faster, but also the decomposition of the human soft tissues will expose new valuable information: The skeleton.
The skeleton of an adult human is composed of 206 bones (excluding some small and often variable ones). This body part can tell a lot about the life and death of the individual in question. Few months ago, the INTREPiD forensics researchers worked on the assembly and preliminary identification of skeletons from the XVIth at the bone laboratory of the University of Leicester.
Skeletons that are found in fairly recent burial sites or mass graves will be the subject of a future post. Here, we are interested in those recovered from ancient archaeological sites (with a tx-t0> 100s of years).
A skeleton that could date back to the XVth or the XVIth century was found in September 2012 under a modern car park here in Leicester city. It was already confirmed to be the site of the old Greyfriars church. He was a man in his early thirties who lived with a severe scoliosis and died from at least one fatal wound at around 1456-1530 AD. His physical appearance and the location and time of his death correlated with a high possibility that he could have been none but Richard the Third, the last King of the Pantagenet dynasty (1452-1485; reigning from 1483 to 1485).
A genetic analysis comparing the DNA of the ancient bones to the DNA of two presumed descendants of the King was performed by scientists at the department of genetics in order to complement the other methods of identification.
Photographs by University of Leicester and Jeff Overs. Portrait of Richard III: Collection of the Society of Antiquaries of London. For more information about the content of these images visit: http://www.bbc.co.uk/news/uk-england-leicestershire-21282241
Overcoming the problem of a large (tx-t0)
If the skeleton is indeed that of King Richard 3, then more than 500 years have passed from the time of his death up until his recovery and preservation. Identifying someone in that case is complicated and bears large uncertainties. Two measures were taken against this natural difficulty:
1- A high sensitivity method was applied
DNA analysis is an extremely sensitive method. Only a minute quantity of the available material (theoretically a single biological cell) is required to generate an informative profile:
2- Targetting resistant and persitent evidence
In the vast majority of naturally occuring environments, the most resistant human body part is the skeleton. Also, and in order to increase the chances of obtaining an informative profile, one must choose the bones that are still relatively in a good condition. Here, the genetic material was extracted from teeth and a well preserved femur bone.
Following a similar logic, the most persistent type of DNA was targeted. Analysis of the mitochondrial DNA is in fact the method of choice when the questioned material is ancient. Every human cell contains one nucleus (source of the nuclear DNA) and possibly thousands of mitochondria (source of the mitochondrial DNA). In the same fashion, every nucleus contains up to 2 copies of the nuclear DNA and every mitochondrion is expected to contain up to 10 copies of the mitochondrial DNA. This indicates that mitonchondrial DNA is ten thousand-folds more abundant than nuclear DNA. Abundance in that case leads to persistence over time:
Forensic scientists and archaeologists are indeed on a mission against the unstoppable and unidirectional movement of time.
The identification process of King Richard 3 helped us shed light on how a multidisciplinary approach can tackle the problem of a large (tx-t0) most efficiently by performing high sensitivity methods and choosing persistent evidence.
The skeleton was laid to rest at the end of March 2015, in Leicester’s cathedral.
We at INTREPiD Forensics have participated in the University-wide Richard III open day on Saturday March 21st 2015. We have reached out to the community at large by creating a number of practical activities and by presenting our posters.
My poster is attached below. Please feel free to comment and ask questions.