What influences have precipitated the change in anthropological methodology and practice in the forensic context?
The last two decades have witnessed a change in anthropological methodology and practice in the forensic context. What influences have precipitated this change and what are the implications to the discipline’s future regarding its application to the judicial process?
The value of biological anthropology to forensic science became increasingly apparent during the last century, culminating with the reception of its off-shoot, forensic anthropology, by the American Association of Forensic Sciences (AAFS) in the 1970s. This landmark event represented the recognition of the anthropological subdivision as a scientific endeavour and, importantly, one that would be relevant in the pursuit of justice. Its relevance lay in the ability of its practitioners to assist constabularies with identifying skeletal remains through the process of biological profiling. Its designation as a science was founded upon its parent discipline’s historic use of quantitative methods and statistics to support classic high-range theory (for example, the apportionment of racial types), and the application of inductive reasoning in the procurement and interpretation of data. There was a call for further refinement in forensic anthropological techniques following the Daubert v. Merrell Dow Pharmaceuticals, Inc., [1995] rulings and indeed great efforts were channelled into the acquisition of method reliability (i.e. accumulating error rates and obtaining universal acceptance of methods) in order to remain within the scientific realm.
Since the 1970s, however, anthropology has found itself in the post-genomic era where rapid advances in molecular science offer alternative and low-risk methods of individualising biological evidence. Although these new techniques are expensive and time consuming, a consequence of the technology’s infancy, it may be surmised that more efficient methods are currently being refined, and an ingress into routine forensic practice is imminent. The consequences to forensic anthropology (referred to as ‘forensics’ from here on) have been ‘paradigm shifting’ in their enormity (Dirkmaat et al. 2008, pp. 34), and relate to the criteria set by both the AAFS and by the court rulings of the 1990s.
Chiefly, anthropology has shifted its goal posts; although DNA analysis can offer efficient positive identification in many circumstances, it cannot offer information about the circumstance and manner of death. To find a niche, and remain relevant to their purpose, anthropologists have therefore become increasingly concerned with the analysis of trauma and taphonomy. This has involved the incorporation of traditional archaeological methods and practice (Boyd and Boyd 2011). The natural consequences of such a shift involve the discipline’s scientific standing because, although traditional anthropology has the might of evolutionary theory behind it, one might argue that the ‘new’ forensics finds itself less well supported by science as defined by the judicial system.
The relevance of any field of study to forensic science is in the provision of expert witnesses for the prosecution (or defence) who must assist the trier of fact in court. Expert witnesses are deemed admissible by the quality of their testimony which, in these circumstances, will depend upon the methods used to ascertain and substantiate the facts. And the methods are only as reliable as the reliability or reputation of the discipline that formulates them (Moore V Ashland Chemical, Inc., 1998). Paramount is the use of the scientific method, which specifies that a discipline’s overarching paradigm must be based upon theories that are testable. In other words, theories must derive from hypotheses that have withstood rigorous testing involving either the process of inductive reasoning, deduction, or a combination of the two (Gorham 2009).
Biological anthropology, for instance, rests upon the foundations of the evolutionary paradigm; a paradigm supported by one of the most tested theories in history. Practitioners of its applied sub-discipline then, whose principle aim is to map morphological variation and recognise the skeletal determinants of individuality, are equipped to testify about matters that have grown ‘naturally and directly out of research conducted independent of the litigation’, and not offering opinion developed ‘expressly for the purposes of testifying’ (Daubert v. Merrell Dow Pharmaceuticals, Inc., [1995] 43F. 3d 1311. 1317). To be sure, experimental data has been obtained for the purposes of testifying, but this data is primarily concerned with substantiating the methods of quantifying human biological adaptation and acclimatization. The research ensures the regulation of error rates, the standardization of methodology and terminology (as stipulated by the courts) and, in response to the rulings, ensures the internal verification by the Board of Forensic Anthropology itself.
Of course methods in forensic anthropology are not entirely robust, hence the need to establish base-lines for error rates, but the point at hand is that the justification underlying the methods (i.e. as established in biological anthropological theory) are valid. For example, one aspect of the biological profile (i.e. the principal expectation of the anthropologist as defined by the law enforcing bodies they are hired by) is skeletal ancestry determination. Biological anthropologists have studied macro-evolutionary processes which drive morphological change through time; they observe patterns in the fossil record, and study the evolutionary processes in extant non-human animals (from Drosophila to Pan). Well equipped, they then formulate hypotheses and make inferences about micro-evolutionary processes (human variation). This justifies the methodology used by their forensic co-workers: namely the landmarks used in craniometric race determination, or the interpretation of the variability (heredity) of non-metric traits.
This established process is an example of induction, and the potential error is an inherent part of the ampliative process; making inferences about a population from observations of a sample (Gorham 2009). But when there is good understanding of the causes behind variation, this leap from sample to population is scientifically justified by theory and hence less risky than inductive methods used in, say, the behavioural sciences (where variables are less well defined, and the direction of causation is more difficult to determine). Hypothetico-deductive methods can then be applied to test observations of variation within samples of extant populations (Komar and Buikstra 2008).
It can therefore be surmised that forensic anthropology, in its traditional sense, is well-grounded in theory garnered from the evolutionary paradigm; a paradigm directly related to the goals of the forensic anthropologist (mapping human variation across space). It has valiantly responded to internal criticisms (Iscan 1998) and met the expectations of the judicial rulings of the 1990s by carrying out extensive research on rapidly growing skeletal reference collections (such as the forensic databank [Ousley and Jantz 2006]) as well as utilising CT and laser scanning techniques to increase the pool of modern samples (e.g. the Zurich virtopsy project). How then might a new anthropology, one concerned with realms outside biological, and traditional osteological analysis, withstand cross-examination by those seeking to verify its scientific foundation?
The development of molecular techniques and their imminent widespread application in the forensic sciences initiated a paradigm shift within forensic anthropology (Dirkmaat 2008). As previously stated, in order to remain relevant to the developing field of forensics, anthropologists have had to develop and expand their applied expertise in the field. Although DNA profiling may become the norm and limit the need for the traditional anthropological skillset in domestic cases, there are circumstances where DNA analysis is not practical. For instance, in response to increasing public awareness of international issues and conflict, there is a growing demand for forensic anthropologists abroad who may aid the recovery and analysis of mass graves in countries where human rights are not upheld by law (Dirkmaat 2008). The very nature of mass graves; their frequency in war-torn countries where personal records are absent, and the very structure of commingled assemblages (where individuals are of the same sex, age, stature and race) extend the expectations made of the anthropologist beyond the determination of biological profiles in their traditional sense (Komar 2003). The personal identifications of skeletal remains must be obtained; the assemblage and the evidence must be individualised.
The personal identification of remains where records (dental x-rays, radiographs etc.) are absent may be possible through the analysis of skeletal determinants of disease and hereditary characteristics, specifically when the families of the decedents are present to consult (Cunha 2006). This naturally involves the application of palaeopathological methods to forensic anthropology and, at first glance, the crossover may seem fraught with difficulty. The goal of palaeopathology is to observe and diagnose skeletal anomalies in the remains of long-dead individuals in the absence of personal and medical records, and consequently the accuracy or reliability of the diagnosis may never be determined. To complicate matters, due to the nature of bone metabolism, myriad causes of pathology with different aetiologies may produce similar effects in the skeleton. Differential diagnosis is often employed, but this deductive method is subject to the experience of the practitioner. It is therefore unsurprising to find little intra-disciplinary agreement regarding operational standards and terminology, and the AAFS stipulated universal acceptance of methods and terminology as inclusion criteria.
The application of operational definitions is a promising solution to the problem of standardisation within palaeopathology and, therefore, has the potential to support the crossover into the field of forensics (Waldron 2009). Operational definitions are strict criteria based upon the presence or absence of pathognomonic indicators. They are supported by modern clinical data and offer standards that can be used by forensic scientists with relatively little experience in palaeopathology and medical science. Furthermore, the operational definition method lies safely within the realm of inductive reasoning; clinical data obtained from modern samples (utilising imaging technologies) will allow research to be carried out on reliability, error rates and the posterior probabilities involved in the leap from sample to population. This research may very well justify the application of palaeopathological methods to the forensic domain.
As well as developing methods to establish positive identification through the analysis of ante-mortem bone modification, anthropologists are becoming increasingly concerned with ascertaining the cause and manner of death in both domestic and international cases. This involves the detection of trauma. Trauma analysis is a rapidly growing field that involves the study of sharp weapon striation patterns, ballistics, and biomechanics in order to understand the effects of violence on bone (Saville et al. 2007). One of the challenges involved in the endeavour is one that may also have a bearing on the study of skeletal indicators of disease. In order to analyse ante- and peri-mortem data, it is first necessary to differentiate damage inflicted upon the skeleton before death from that incurred after burial or, in other words, to distinguish pathophysiological modifications from pseudopathology. The efficacy of this endeavour is naturally dependent upon the completeness of recovery and upon site processing methods, because the depositional environment (a record of soil type, foliage and insect/carnivore activity) may be informative about the sources of potential pseudotrauma and pseudopathology.
Reconstructing the events leading to the creation of a crime scene necessitates the evaluation of the site formation process; a strategy which increases the probability of the complete recovery of skeletal remains and evidence. It is in this exercise that forensics incorporates traditional archaeological methods. These methods are based upon reconstruction and agency theory (Boyd and Boyd 2011), both of which use non-linear systems to model multivariate interactions between agents, artefacts and environment. Where these academic domains depart from those of traditional anthropology is in the incorporation of the analysis of behaviour at the individual level. Whereas population-level behavioural models are an accepted method of testing traditional anthropological theories (such as social learning strategies [Laland 2004] etc.), its application here, where ‘agent’ refers to the decedent as well as any other individual who may have participated in the formation of the scene, may test the limits of the uniformitarian principles inherent in this type of analysis (Knapp and Dommelen 2008).
In addition to the site processing methods of archaeology, the study of taphonomy has been adopted by forensic science and is indeed a necessary course of study for the ‘new’ forensic anthropologist who may use taphonomic data to determine post-mortem interval. Taphonomy is the investigation of the sum processes that transform an organism into the products of decomposition which, ultimately, infiltrate the depositional environment. Its object of study then may be characterised by an open or complex system and, historically, open systems have been notoriously immune to unification, quantification, and modelling (Gleick 1988). Furthermore, and like many forensic fields, taphonomy is a rapidly growing area of study and, due to the nature of the biological and geological systems involved, is multidisciplinary in its approach (Haglund and Sorg 1997). In fact, it is the scope and complexity of taphonomy that poses problems to those seeking to retain the scientific foundations of forensic anthropology (Nordby 2002).
As well as the problems posed by the type of data to be analysed by taphonomists, there are issues surrounding the methods used to study them. The scientific process must generate knowledge developed from experimentation under controlled conditions. This ensures that relationships between variables are understood to the extent that theory, born of the experiment, may be generalised. There is, however, a dearth of primary material to experiment with; over its existence society has evolved strict protocols concerning the treatment of human remains, and subjecting the deceased to scientific experimentation has long been considered taboo (Haglund and Sorg 1997). Thus, the anthropologist has had to develop skills ‘along the way’ expanding and perfecting his method with each real crime he is invited to assist with. Unfortunately, it is yet to become standard practice for anthropologists to be involved in the initial phases of investigations, and taphonomic data has often been perceived as ‘impressionistic’ or ‘anecdotal’ by scientific classicists as a result (Nordby 2002).
It is often necessary to compensate a lack of primary material by substituting human for non-human animal remains in taphonomic experiments (Janaway et al. 2003) but this does leave the expert witness vulnerable in court. In order to address this problem, in the 1990s Knoxville University’s Bill Bass began the research project commonly referred to as the ‘Body Farm’ (Bass and Jefferson 2003). Dr Bass deposits donated cadavers in a range of manipulated environments to simulate the taphonomic process under controlled conditions. Although he was initially met with criticism and even threats from the public, Dr Bass’ pioneering project is now heralded as a new phase in forensic research, and public perception has gone from revile to curiosity with rates of donors and funding increasing every year (2003). It is now possible for students to harvest sufficient quantitative data from prospective longitudinal studies to apply statistical models, and predict experimental outcomes in the manner required to satisfy the scientific method and its community (Haglund and Sorg 1997).
It can be seen that forensic anthropology has grown in its scope and objectives since its formal recognition as a forensic discipline in the 1970s. To begin with, whereas traditional anthropology was concerned with establishing the biological profile of skeletal remains, the ‘new’ anthropology is looking beyond to determine presumptive or personal identification in an international setting. Problems inherent in individualizing evidence (whether skeletal or artefact) lie in the risks involved in making inference during the evaluation of the evidence. When there is a lack of universal protocol and terminology in a discipline (such as palaeopathology), the act of inference becomes increasingly subjective. In a judicial setting, where error rates are integral in order to assist the trier of fact, methods must be explicit, logical, and intelligible to a lay-man jury. The application of operational definitions is a simple and effective resolution to the problem of subjective inference. The responsibility of the diagnosis is removed, to an extent, from the anthropologist to the method itself and further research into correlating skeletal pathology with known cases (to obtain probabilities) is inspiring confidence in both the procedure and the discipline as a whole.
As well as increasing the efficacy of the biological profile to presumptive identification, anthropologists are exploring new areas of skeletal analysis in order to assist with determining the cause and manner of death. Reconstructing the events leading up to death requires a reconstruction of the crime scene itself. Utilising archaeological methods to survey the land (for successful recovery), and to process the site for evidence enables the anthropologist to analyse the skeleton within the context of the site. It should be apparent that in order to successfully apply these archaeological methods in the field, the anthropologist must be among those first at the scene. In fact, it could be argued that it is the removal of the anthropologist from her lab and into the field that really defines the difference between the old and the emerging applied forensic anthropology. Unfortunately, it is still not standard practice for the anthropologist to be among those called during the initial stages of the investigation and, consequently, the anthropologist often carries out the analysis within the confines of his lab, and unfamiliar with the depositional environment.
A good understanding of taphonomy is required to establish time since death as well as aiding the determination of cause of death and, again, this necessitates a visit to the scene. But where these applied anthropological techniques depart from traditional anthropological practice is in the adoption of methods from within disciplines which lack robust paradigmatic frameworks. A robust paradigm is required to justify the leap from sample to population/theory during analysis, and the lack may hinder progress in forensic fields because unifying theory provides the stability and confidence of a scientific method. Nevertheless, new developments in taphonomic research, born of a shift in societal perceptions of forensic work, is enabling experimentation to be carried out on post-mortem interval. A brief perusal of the literature will reveal how students of taphonomy are scientists who use scientific methods to design experiments, collect data, and apply statistical models. Due progress over the next decade or so within taphonomy and palaeopathology will therefore surely contribute to the construction of a modern, relevant and ‘healthy’ forensic anthropology.
References
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