The Babel research group : “From the diversity of populations to the individual, from identification to identity”

Head of the laboratory: Pr. Bertrand LUDES

1. Presentation of the BABEL research unit

1.1. Introduction

The research unit BABEL (Biology, Anthropology, Biometry, Epigenetic, Lineage)originated in the need to respond to a social imperative that has become increasingly important in recent years: recovering the identity of individuals that perished in mass events (terror attacks, natural disasters, crashes of planes and other vehicles, deceased migrants of the roads of exile) on national and international territories. The research unit is composed of researchers from the CNRS (French National Center for Scientific Research), Professors of Universities, and practitioners from the IML (Institute of Legal Medicine of Paris). The interdisciplinary approach proposed by these researchers assembled into a single research unit can constitute the basis of an innovating research at the intersection of biological sciences, medical sciences and social sciences based on data originating from forensic cases.

The IML is a public service for the city of Paris and the departments of Hauts-de-Seine, Seine-Saint-Denis and Val-de-Marne. It is attached to the Paris Police Prefecture under the Police Prefect’s capacity of special communal administrative policing. The missions of the IML lead to the development of original, innovative research, using the very latest technologies of forensic sciences and medical anthropology, as they relate to thanatological and clinical analyses.

Because of the sustained activity of the IML, that takes in 3000 corpses every year (among whom 400 are not identified), it is necessary to set up effective technical platforms when it comes to identification. This is due both to the confrontation with fundamental issues that cannot be resolved by routine methods and especially to the need for an efficient response to emergency situations that necessitate specific developments.

Concerning research, the development of the study of biological profiles, especially the analysis of phenotypical traits, must be supported by the study of past populations, given the legal restrictions in genetic identification in France. Our approach is intent on answering important social concerns linked with the current international context (migrations, terrorism, impact on the psyche of the affected populations as it relates to their bio-geo-cultural origin) through the study of biological and cultural identity. It must be specified that all the analyses are performed under the request of the prosecutors.

BABEL is supported at the international level by the European Academy of Legal Medicine that facilitates cross-border collaboration in legal medicine and forensic science, as is the case with the “European Forensic Health Practitioners Network” (Euro-ForP) program led by Pr. Patrick Chariot (Paris XIII) and Pr. Cristina Cattaneo from the Milan IML, that is especially involved in the study of migrant identification, the role of our unit will be to collect the family data of missing persons.

The Research unit is carried by two directing institutions: the French National Centre for Scientific Research (CNRS) and the University of Paris and one partner institution: the Police Prefecture of Paris.

1.2. Societal and scientific issues

Humans are defined by their identity, be it dependent on kin, administration or biology. Identity contains all parts of an individual’s history, making them unique and therefore identifiable within the population.

The BABEL team wishes to develop interdisciplinary research about human biological and cultural identity, focused on the issue of the identification of deceased persons. The reconstruction of the individual history of a person, from their origins to their most recent past, allows their community to recover them after death, despite the circumstances of that death, that led to loss of identity.

With skills in the medical, biological and psychological fields, we intend to apprehend death in a global approach, from the identification of the deceased, the analysis of the circumstances of their death to the interactions and exchanges with their family and community. This strategy is the first of its kind to be implemented in France and it allows for collaboration on an international level (notably with Milan: Pr. Cristina Cattanéo), with a topic that is a major issue across borders and an important European question.

The missions of the IML consist in receiving the corpses of deceased individuals from Paris and the immediate suburbs, as well as those deceased abroad whose identity could not be established and/or whose death justifies medical examination. On average, 400 to 500 bodies received by the IML every year are unidentified (out of a total of 3000). Among them, 75 to 100 will then have to be inhumed without identification. For the families and their group, the loss of identity entails social and affective ruptures: the fate of the missing person remaining unknown, it is impossible to start the grieving process. Recent terror attacks or mass accidents highlighted the anguish of families and the pressure on society to bring them swift answers. In that context, the main topic of research will be the restitution of identity, in cases where this has been lost for a diversity of reasons (corpses transformed by decomposition or the circumstances of death). The body must indeed be returned to his social group, which implies the necessity of recognising this group through the understanding of their cultural behaviours.

In fact, both the identification of migrants, deceased in large numbers on the roads of exile, and the identification of individuals that died isolated (which includes the analysis of the place of discovery of the corpse) have become judicial, public health and ethical issues in numerous countries.

In the current context of international terrorism, natural disasters and multiple migrations, identification methods must be at once swift, reliable and efficient: the restitution of a body to their family depends on it. One of the main issues therefore, is to improve and optimise the process of identification when none of the usual elements of comparison (fingerprints, genetics, odontology) are present. This is namely done by developing biogeographical origins research and identification from tissues degraded by putrefaction and/or burning through the combination and development of the methods of forensic medicine, physical anthropology and biochemical analysis.

Another important issue is the determination of the circumstances of death, through the development of analyses of lesions in modern populations, in subjects both alive and deceased, as well as using data collected on ancient populations.

2. Research topics

2.1. Individual identification

Biological anthropology is the study of human variability from the origins until modern times. Human biological variability, which depends on micro and macro-evolutionary processes that gave rise to the extreme bio-cultural differentiation, characterises our species. Studying the biological diversity of human groups will allow us to more precisely define the criteria for the identification of single individuals.

Molecular anthropology

The genetic identification of individuals and the determination of biological kinship are essential missions in the practice of legal medicine. Our team’s objective in those regards is twofold: first, it aims at taking advantage of Next Generation Sequencing (NGS) that allows for highly-efficient analyses, able to resolve complex cases (for example, the identification of an individual using comparison with the genetic profile of a maternal cousin).

Secondly, we will endeavour to develop statistical approaches to establish kinship reliably in the absence of vital records. This is especially necessary for genetic tests within families with different levels of inbreeding, family reunification cases or identification in mass graves, all of which necessitate novel statistical approaches.

The analysis of haplotypes and haplogroups allows confirmation of the ethno-geographical origin of the subjects studied. These molecular analyses will be confronted to physical anthropology analyses, for increased accuracy.

The establishment of “genetic photo-fits” is of great assistance to police inquiries. It necessitates the identification of phenotypical traits beyond eye, hair or skin-colour; we will therefore endeavour to describe and implement the analysis of other markers of the external appearance of individuals such as the height of individuals, the early baldness or facial morphology.

2.2. Forensic anthropology

This approach is concerned, in practice, with the establishment of the biological profile of a subject, the description of ancient skeletal lesions that can contribute to the identification of the subject and/or the description of recent skeletal lesions that can contribute to the determination of the cause and circumstances of death.

The biological profile

Recent terror attacks that implicated large numbers of victims highlighted the issue of the rapid identification of dead bodies, demanded by the families of the deceased and the authorities, which impose maximum delays of less than a week.

Because formal identification methods (genetics, odontology and dactyloscopy) are based on comparative analysis, the production of the biological profile of a victim (sex, age, stature, peculiar characteristics) is essential for the orientation of research and the gathering of the elements that are relevant to the comparison process. The BABEL group will endeavour to develop identification methods that are efficient in the absence of those criteria for comparison.

Thus, the multidisciplinary team associated with the BABEL project, constituted of medical examiners, anthropologists, radiologists, odontologists and biologists will be able to collect, analyse and compare skeletal and dental data in all fields of expertise, in order to set up a fast, single protocol for the determination of a reliable and relevant biological profile.

After formal identification, the data will be further analysed as an evaluation of the discriminating power of the different dental and skeletal techniques, especially in relation to age and sex, thus allowing us to improve the methods of examination of the biological profile.

Skeletal injuries

This topic of the potential of bone injuries is based both on macroscopic observations of the skeleton and on a microscopic and taphonomic approach.

Knowledge of the microscopic structure of bone tissue and its principal functions (mechanical, metabolic) is essential in apprehending the different analytical aspects of the biological profile and skeletal lesions. As a living hard tissue, the bone retains the trace of various events which can be identified through analysis as the results of trauma and/or pathological conditions. Bone lesions can provide important information in the identification of a corpse (for example presenting a specific healed fracture and/or occupational traits) and in the determination of the cause and circumstances of death. On the opposite of skin tissues, which is composed of elastic tissue, bones retain marks and traces of wounding objects.

The morphological characteristics of bone lesions often allow the identification of the wounding mechanism (blunt, cutting/piercing/slashing, ballistic, thermic) and therefore the wounding object or objects. The confrontation of bone lesions and soft tissue lesions is then essential. Macroscopic and microscopic examination of bone lesions also allow us to estimate the sequence of traumatic events in relation to the moment of death (ante-mortem, peri-mortem and post-mortem). The proliferation, for instance, of new bone formation around a fracture indicates an early response to trauma by a living organism, therefore necessarily before death.

Complementing macroscopic analysis, radiological examination (Micro-CT, Quantum Fx (Perkin Elmer), at the Faculty of Dental Surgery, University of Paris) and histological analyses permit the identification of the traumatic or pathological nature of bone lesions. These methods also gather chronological information through the study of the stages of bone restoration.

Histological bone analysis also highlights the presence of exogenous particles, linked to the environment in which the event occurred or the wounding object itself. For instance, the presence of particles of metal and paint, left by the blade of a saw on the spongy or cortical matrix of the complete section of a limb in a case of dismemberment, constitute an element of proof that is identified under a microscope and characterised by complementary physical and chemical analyses.

Microscopic examination of bone tissue also permits the study of issues caused by the circumstances of the decomposition of the corpse (taphonomy) and thus the evaluation of the interval between the death of the individual and the discovery of the corpse (post-mortem delay).

3. Methodological issues

The genetic identification of individuals

Current genetic analyses imply the typing of two categories of genetic markers: microsatellites or STR (Short Tandem Repeats) and punctual polymorphism in the DNA sequence, or SNP (Single Nucleotide Polymorphisms). Autosomal STRs are used for the determination of the genetic profile of an individual and the identification of close biological links, namely kinship with their direct descendants or ascendants. These markers are the essential content of all current databases (among which the Automated National Database of Genetic Imprints, or FNAEG). This allows the constitution of data archives and international exchanges through Interpol.

The analysis of autosomal STR can be complemented by the study of STR from the Y-chromosome, which characterises paternal lines, and the study of mitochondrial SNP, which characterises maternal lines. Even the combination of these methods can however reach limitations when analysing complex cases (degraded DNA, inbred families, absence of a reference or comparable profile…).

The NGS approach proposed by our team will be developed in order : (i) to analyse STR at a higher resolution, by sequencing the repeated patterns rather than just account for the number of repetitions, thus revealing new aspects of the genetic diversity in populations where the genetic diversity of classical markers is low; (ii) to target SNP when the DNA molecule is too degraded for the study of STR (SNP typing being less sensitive to fragmented DNA than STR typing) and (iii) to sequence complete mitochondrial genomes where the characterisation of maternal lines is essential to the identification of an individual.

Epigenetics and age determination

Epigenetic analyses are concerned with the chemical and environmental modifications of DNA, which can be methylated and/or compacted by different histone proteins, which can themselves be modified. The mechanisms that modulate the expression or the repression of genes, that is to say their transcription, without changes to their sequence, are sensitive to factors in the environment.

In recent years, the study of CpG sites on methylated DNA has appeared as one of the most promising means to establish the age of an individual from their DNA.

This application could facilitate the identification of human remains and improve the characterisation of phenotypic traits such as hair colour (where for instance greying hair can be associated to the advanced age of an individual). Several studies have been performed using blood, saliva, sperm or even teeth as sources of DNA, with cohorts of several hundred individuals including monozygotic twins.

Freire-Aradas et al. (2016 Forensic Sci Int. Genetics, 2017 Forensic Science Review), recently proposed a test based on 7 methylation markers. On the basis of this work, we will develop a method for the determination of age from bone remains, in order to establish an original method, at the interface of forensic sciences and anthropology. This study can be implemented using the EpiTYPER technology with Maldi-Tof mass spectrometry (Agena Biosciences). It will allow us to determine if bone material is a functional basis for the determination of age at death.

Epigenetics and stratification of populations

Population analyses of epigenetic markers also allow for the recognition of different populations and the attribution of a defunct individual to his population of origin (Barflield et al. Genet Epidemiol 2014, 38(3): 231-41). Methylation levels vary between individuals of different ethno-geographical origins in a manner comparable to other markers. The combination of dispersion and clustering analyses for different types of markers appears to provide more accurate and specific population determination.  Our team will develop these methods of identification using the samples collected during fieldwork by the CNRS researchers in the team.

Ethno-geographical origins and phenotypical traits

In the absence of elements of comparison that allow for the confrontation of two genetic profiles, the advancement of police inquiries can benefit from other elements of identification. Such elements can be the ethno-geographical origins of an individual and/or the determination of phenotypical traits such as eye, hair or skin colour. Ancestry informative markers (AIM) permit an estimation of the origins of the subject using models that were constructed with allelic frequencies in different populations. Some traits can be identified by the analysis within pigmentation genes. Geographical origins are also apparent through the study of SNP on the Y-chromosome and mitochondrial DNA, by the definition of haplogroups and their relative proportions in different regions of the world.

Physical and forensic anthropology

We intend to develop new methods for the acquisition and rapid interpretation of data from bones and teeth using medical imagery (a 64-sensor scanner, GE Lightspeed, General Electric Systems, Milwaukee, WI, installed at the IML and a micro-scanner Micro CT Quantum Fx, (Perkin Elmer), installed at the Faculty of Dental Surgery, University of Paris) to establish a biological profile, in relation with identification issues specific to each case.

Our team also wished to gather and share new skills in the microscopic analysis of remains, in order to develop new histological techniques for the study of bones and teeth.

Because bone is a matrix requiring difficult work, bone histology is underdeveloped, especially when it comes to degraded material. We have begun the development of an analytical methodology that would be applicable to forensic cases, as well as archaeological samples. This methodology is based on methods that complement one another: imagery (Micro CT Quantum Fx, (Perkin Elmer)) and histology. The first results confirm the power of this double-analysis that allows for digital archiving and the precise 3D exploration of samples, allowing in turn for the targeting of specific regions for histological studies.

Bone histology is also efficient in characterising taphonomy through the study of diagenesis, in forensic cases and anthropology, using recent or ancient samples. Skeletal analysis, in humans or animals, also provides information concerning the conditions in which corpses were transported, deposited, buried, degrader or preserved. Our research will improve the precision of these determination of the factors that modified biological remains (biotic factors, such as rodents or carnivores and abiotic, such as meteorological conditions etc.). In this domain, the study of ancient remains is essential. The work performed by our team will concern the state of physical and chemical preservation of skeletons and bone tissue.

Teeth are a reference point often used to determine the growth stages of an individual. Indeed, teeth formation follows well-defined processes with a precisely established timeline. Studies based on the sequence of teeth eruption, a method which is already widely used to give an approximate age to non-adult/immature individuals, can be completed by the analysis of chronological markers found in dental tissues (enamel, dentine, cementum).

Growth lines make it possible to follow and characterise the successive steps of the formation of a tooth, and counting them also allows us to estimate the timeline of its formation. Therefore, dental histology studies can give precise ages to individuals. Furthermore, dental histology studies may allow the calibration of differences in the formation processes between human populations and the characterisation of these populations. At the same time, they would provide more reference markers useful for the identification of individuals.

Analysis of isotopes and identification

The determination of isotropic relations by mass spectrometry is a technique which can be used to help identify a body. The benefit of stable or radiogenic isotopes lies in the fact that analysing them in human tissues allows us to determine the origin of human individuals or groups. It is preferable to study tissues which undergo little change over time, such as tooth enamel, hair or bone.

Isotopic abundance (2H, 13C, 15N, 18O, 34S, 66Zn) in the different tissues gives an isotopic image of what the individual has eaten in their recent history, and also the recent geographic mobility, or the trophic level of a mammalian species. A person’s diet and geographical localisation influence the isotopic composition of their tissues, such as hair, teeth, nails and bones. Thus, isotopic compositions of hydrogen and oxygen in bones and teeth are calibrated indicators of climate (i.e. temperature), and of the water ingested by an individual. They are considered excellent trackers for human geographical migration, and can therefore constitute an additional source of information to identify an individual.

4. Setting up a socio-biological – or ethno-biological – research project

Because we wish to establish a very active interface with social sciences, we will develop an ethno-psychological approach based on the relatives who come to the forensic institute, and on the skills of the team of psychologists who works there. We will also endeavour to appeal to researchers interested in this subject, and inviting them to join our unit namely the research group of the “Centre d’Anthropologie Culturelle” of the university Paris Descartes.

An ethno-psychological approach will complete the aforementioned studies. This interdisciplinary approach will focus on the exchange of the family of the deceased when their remains are returned to their families, within the Paris IML. It is at this moment that the identity of the deceased will be confirmed. The Paris IML received groups of various origins and cultures. Thus, the BABEL project benefits from synergistic skills, associating psychology, anthropology, genetics and medicine.

Once the deceased has been identified, the question of care for their relatives will be studied through psychological and ethno-psychological analyses, based on our Institute’s experience in this area. Indeed, in our capacity as hosts of the families of the deceased, we meet people of different cultures, geographical origins, and religions. Thus, for families whose roots are for example in the African continent, we have (empirically) noted different perspectives in seeing, feeling and expressing the emotions caused by the loss of a relative. Practices and beliefs differ, and are linked closely to those families’ religion and culture. Geographical, cultural and religious origins create a specific perception of death, linked to specific ethnic groups.

The various approaches to the identification of a group or an individual will make it possible to reconstitute a group’s identity based on the individuals which make it up. This theme is what gives the BABEL research group its originality, which will direct its work toward characterising the diversity in human populations and in the identification of individuals, by associating the study of environmental factors, the study of phenotypical and genotypical variations and an ethno-psychological approach.

Thanks to the experience of this team’s researchers, who are already involved in the study of the diversity of human populations (both modern and ancient), and have mastered innovative technologies, the BABEL project benefits from certain skills which form a synergistic association of anthropology, genetics, psychology and medicine. These skills will make it possible to provide answers to major current social issues, such as those caused by natural or other disasters, international terrorism, population displacements or migrations, whether they are individual or massive.

5. From theory to practice: the duty of memory and identification

We have taken part in the process of identifying a World War I combatant (“poilu”) whose remains were found on the Verdun battlefield, and also helped identify four fighters from the Resistance, executed by Nazi squad during the Second World War, near Toulouse. The identities of these five people were established, allowing their families to know the stories of their relatives, lost during the war, and for some, to bury them with military honours. Despite the passing decades, our group has seen how identification is important to the families of the deceased, putting an end to years of uncertainty about the ultimate fate of their relatives. This same uncertainty is shared by the families of migrants who died in exile.

According to historian Stéphane Tison, the implication of human groups in the identification of their relatives who died in mass-death events, has its origin in France after the First World War. Indeed, in 1914, even though the Germans and Americans have been using an individual burial system for several years, mass graves are still the widespread practice for most of the armies.

For the families of those soldiers killed on the battlefield, as well as the population in general, the image of anonymous cadavers heaped into mass graves has become scandalous. From 1915 onwards, these reclamations having been acknowledged, a new funerary policy is implemented, based on the following principles: identification of the deceased, individual burial in a coffin, informing the family, organising – if possible – a funeral in accordance with the religion of the deceased, upkeep of the grave, regrouping and in some countries, returning the remains to the families.

This historical aside shows how much these individual and societal concerns are relevant today. Recent terrorist attacks in France have shed light on the families’ need to identify and recover their lost relative, on the importance for the media to report on the events and on the lives of the victims, and on the wish to commemorate these events and victims at the state level.

The families of thousands of migrants, whose bodies wash up on the Mediterranean shores, have the same needs. The same is true for the families of deceased individuals who end up in forensic institutes without an identity. Identification of one individual or a large number of bodies is not only a forensics issue, it is also an ethical, legal and societal issue.

The multidisciplinary BABEL team, whose skills are medical, biological and psychosocial, proposes to take a global approach to death, involving the identification of the deceased, the analysis of the circumstances of their death, and interviews with their family and social group.