Analysis of artificial radiocarbon in different skeletal and dental tissue types to evaluate date of death

Radiocarbon dating, with special reference to the modern bomb-curve, can provide useful information to elucidate the date of death of skeletonized human remains. Interpretation can be enhanced with analysis of different types of tissues within a single skeleton because of the known variability of formation times and remodeling rates. Analysis of radiocarbon content of teeth, especially the enamel in tooth crowns, provides information about the date of formation in the childhood years and in consideration of the known timing of tooth formation can be used to estimate the birth date after 1950 ad. Radiocarbon analysis of modern cortical and trabecular bone samples from the same skeleton may allow proper placement on the pre-1963 or post-1963 sides of the bomb-curve as most trabecular bone generally undergoes more rapid remodeling than does most cortical bone. Pre-1963 bone formation would produce higher radiocarbon values for most trabecular bone than for most cortical bone. This relationship is reversed for formation after 1963. Radiocarbon analysis was conducted in this study on dental, cortical, and trabecular bone samples from two adult individuals of known birth (1925 and 1926) and death dates (1995 and 1959). As expected, the dental results correspond to prebomb-curve values reflecting conditions during the childhoods of the individuals. The radiocarbon content of most bone samples reflected the higher modern bomb-curve values. Within the bone sample analyses, the values of the trabecular bone were higher than those of cortical bone and supported the known placement on the pre-1963 side of the bomb-curve.     

A Review of Bomb Pulse Dating and its Use in the Investigation of Unidentified Human Remains

In cases where there is limited antemortem information, the examination of unidentified human remains as part of the investigation of long-term missing person's cases is a complex endeavor and consequently requires a multidisciplinary approach. Bomb pulse dating, which involves the analysis and interpretation of 14C concentration, is one technique that may assist in these investigations by providing an estimate of year of birth and year of death. This review examines the technique of bomb pulse dating and its use in the identification of differentially preserved unknown human remains. Research and case studies implementing bomb pulse dating have predominantly been undertaken in the Northern Hemisphere and have demonstrated reliable and accurate results. Limitations were, however, identified throughout the literature. These included the small sample sizes used in previous research/case studies which impacted on the statistical significance of the findings, as well as technique-specific issues. Such limitations highlight the need for future research.     

Radiocarbon dating as tool to assist in triaging cases of unidentified human remains in Victoria,Australia: A case series

In cases where human remains are unidentified because there is no initial identification hypothesis, limited contextual information, and/or poor preservation, radiocarbon (¹⁴C) dating may be a useful tool to further assist with identification. Through measuring the amount of ¹⁴C remaining in organic material, such as bone, teeth, nail, or hair, radiocarbon dating may provide an estimated year of birth and year of death for a deceased person. This information, may assist in, establishing whether a case of unidentified human remains (UHR) is actually of medicolegal significance and therefore, requires forensic investigation and identification. This case series highlights the application of ¹⁴C dating to seven of the 132 UHR cases in Victoria, Australia. Cortical bone was sampled from each case and the level of ¹⁴C was measured to provide an estimated year of death. Four of the seven cases analyzed contained the levels of ¹⁴C consistent with an archeological timeframe, one contained a level of ¹⁴C consistent with a modern (i.e., of medicolegal significance) timeframe, and the results for the remaining two samples were inconclusive. Applying this technique not only reduced the number of UHR cases in Victoria but also has investigative, cultural, and practical implications for medicolegal casework in general.     

Estimation of age from a tooth by means of racemization of an amino acid, especially aspartic acid--comparison of enamel and dentin.

In a study of age estimation from teeth by means of measuring racemization of aspartic acid (Asp), a representative amino acid, the accuracy of data from enamel and dentin in the same tooth was compared. The correlation of D/L ratio of aspartic acid with actual age gave the following parameters: r = 0.928, sigma = +/- 5.2, k = 4.47 x 10(-4) yr-1 in enamel and r = 0.995, sigma = +/- 1.4, k = 5.75 x 10(-4) yr-1. The difference in ages between one estimated by the D/L ratio and the actual one was within +/- 3 years in dentin, while in enamel an error of from 2 to 11 years was observed. Reaction rate constants of the racemization in a dry postmortem state (15 degrees C) were calculated as k = 9.70 x 10(-8) yr-1 in enamel, and k = 1.33 x 10(-7) yr-1 in dentin. Compared to rates determined from teeth recently extracted from living subjects, the rate was higher in dentin than in enamel. These data reconfirmed that dentin is superior to enamel in making exact age estimations from teeth.     

Artificial radiocarbon as an indicator of recent origin of organic remains in forensic cases.

From 1950 to 1963 atmospheric testing of thermonuclear devices produced elevated levels of artificial carbon-14 in the atmosphere. Terrestrial organic material from that time period displays carbon-14 activity nearly twice the pre-1950 levels. Measurement of the carbon-14 activity within organic specimens from forensic cases can reveal if the material dates before or after about 1955. Such information can prove important in some cases in determining if the material is sufficiently recent to be of forensic concern. Application of this technique to an unidentified human skeleton from the American southwest is discussed.     

Personal identification of cold case remains through combined contribution from anthropological, mtDNA, and bomb-pulse dating analyses

In 1968, a child's cranium was recovered from the banks of a northern Canadian river and held in a trust until the "cold case" was reopened in 2005. The cranium underwent reanalysis at the Centre for Forensic Research, Simon Fraser University, using recently developed anthropological analysis, "bomb-pulse" radiocarbon analysis, and forensic DNA techniques. Craniometrics, skeletal ossification, and dental formation indicated an age-at-death of 4.4 ± 1 year. Radiocarbon analysis of enamel from two teeth indicated a year of birth between 1958 and 1962. Forensic DNA analysis indicated the child was a male, and the obtained mitochondrial profile matched a living maternal relative to the presumed missing child. These multidisciplinary analyses resulted in a legal identification 41 years after the discovery of the remains, highlighting the enormous potential of combining radiocarbon analysis with anthropological and mtDNA analyses in producing confident personal identifications for forensic cold cases dating to within the last 60 years.     

Radiocarbon analysis of dental enamel and bone to evaluate date of birth and death: perspective from the southern hemisphere

Radiocarbon analysis was conducted on dental enamel, cortical bone and trabecular bone from four human adults from Andean Peru with known birth dates and death dates, the latter all falling within the modern bomb-curve period. Radiocarbon results were compared with known tropospheric values from the southern hemisphere. The results demonstrate that dental enamel can provide useful information regarding birth dates in consideration of known formation times of the specific teeth examined if the radiocarbon values fall within the modern bomb-curve period. Trabecular bone radiocarbon values are closer to the tropospheric values at the date of death than are values from cortical bone reflecting relative differences in the rate of bone remodeling in those tissues. Age at death also represents an important factor.     

The application of amino acid racemization in the acid soluble fraction of enamel to the estimation of the age of human teeth

Estimation of age-at-death for skeletonised forensic remains is one of the most significant problems in forensic anthropology. The majority of existing morphological and histological techniques are highly inaccurate, and show a bias towards underestimating the age of older individuals. One technique which has been successful in forensic age estimation is amino acid racemization in dentine. However, this method cannot be used on remains where the post-mortem interval is greater than 20 years. An alternative approach is to measure amino acid racemization in dental enamel, which is believed to be more resistant to change post-mortem. The extent of amino acid racemization in the acid soluble fraction of the enamel proteins was determined for modern known age teeth. A strong correlation was observed between the age of the tooth and the extent of racemization. No systematic bias in the direction of age estimation errors was detected. For the majority of teeth analyzed, the presence of dental caries did not affect the results obtained. In a minority of cases, carious teeth showed a higher level of racemization than would be expected given the age of the individual. These results indicate that amino acid racemization in enamel has the potential to be used in age estimation of skeletal remains.     

咬痕个体识别的比对方法

目的 建立一个牙模数据库,为通过牙齿、咬痕进行个人识别的研究及其在法医实践中的应用提供一种新方法。方法 经过对400例牙模进行分析、计算,将牙齿的形状、排列转换成数字型(X,Y)坐标,通过计算出每颗牙关键点与坐标原点的相对位置,在DOS系统下运用Borland C++5.0语言编写程序,快速地计算出牙齿和牙弓的特征。结果 能对牙模进行自动识别,达到排除与认定。其比对精度长度为1.3mm,角度3°;可取的最少牙点位数目为12～14较为合理,大致需要5～7个完整的牙痕。结论 该方法是研究咬痕与牙模比对的基础。     

Reproducibility of radiographic stage assessment of third molars

The aim of this study was to determine intra- and inter-observer variability of the developing third molar from panoramic radiographs. Formation of third molars was assessed according to stages described by modified Demirjian et al.'s methods: Moorrees et al. [C.F.A. Moorrees, E.A. Fanning, E.E. Hunt, Age variation of formation stages for ten permanent teeth, J. Dent. Res. 42 (1963) 1490-1502] and Solari and Abramovitch [A.C. Solari, K. Abramovitch, The accuracy and precision of third molar development as an indicator of chronological age in Hispanics, J. Forensic Sci. 47 (2002) 531-535]; in addition, data were also analysed unmodified, i.e. Haavikko [K. Haavikko, The formation and alveolar and clinical eruption of the permanent teeth, an orthopantomograph study, Proc. Finn. Dent. Soc. 66 (1970) 104-170] and Demirjian et al. [A. Demirjian, H. Goldstein, J.M. Tanner, A new system of dental age assessment, Hum. Biol. 45 (1973) 211-227]. The sample was a random selection of 73 panoramic radiographs from patients aged 8-24 years. After training, the left maxillary and mandibular third molars were scored on two separate occasions without knowledge of previous scores. Cohen's Kappa and percentage agreement were calculated for each method, for maxillary, for mandibular third molars and combined. Percentage agreement for stages was also calculated. Intra-observer agreement was greater for mandibular third molars compared to maxillary third molars, and better for methods with fewer stages. Kappa values indicated good agreement for most methods; the best was Demirjian et al.'s method for mandibular third molar with very good agreement (K = 0.80) for the first author, good agreement for the second author (K = 0.75) and good agreement between observers (K = 0.75). The stages with best agreement were Demirjian's stage E [A. Demirjian, H. Goldstein, J.M. Tanner, A new system of dental age assessment, Hum. Biol. 45 (1973) 211-227] and Moorrees et al.'s stage Cc and R1/4 [C.F.A. Moorrees, E.A. Fanning, E.E. Hunt, Age variation of formation stages for ten permanent teeth, J. Dent. Res. 42 (1963) 1490-1502]. CONCLUSIONS: Having clearly defined stages and fewer stages allowed better reproducibility of third molar formation.     

Suspect graveyard burial (South Armagh,N. Ireland): Combined search,forensic anthropology and radiocarbon dating

Geophysical investigation of a former convent graveyard for conversion to a community centre identified an unrecorded, unmarked burial below a later burial. Archaeological excavation confirmed the presence of skeletonized human remains, considered by police as a possible clandestine burial. Mortuary examination indicated the remains belonged to a mature adult female. To determine whether the deceased could be a recorded missing person, radiocarbon dating was undertaken on a femur and a rib bone. This is not always straightforward, and results showed two possible ages due to intercepts on either side of the nuclear weapons testing spike in atmospheric ¹⁴C; however, the later dated burial allowed us to constrain the date of a rib to CE 1959. This study demonstrates that dating a second tissue with a longer turnaround time, such as a femur, can help to constrain which side of the bomb spike is most probable. This paper documents in one work the search, scene and sample and then advances this to resolution by anthropological analysis and radiocarbon dating of human remains.     

Using Carbon,Oxygen, Strontium,and Lead Isotopes in Modern Human Teeth for Forensic Investigations: A Critical Overview Based on Data from Bulgaria

Isotopic data obtained from human remains can provide information about an individual's origin, migration, and diet. We evaluate the usefulness of carbon, oxygen, strontium, and lead isotopes for forensic investigations by comparing data from Bulgarian teeth with data from other regions. Geo‐referencing based on oxygen or strontium isotopes can be misleading due to overlap with other countries in Europe and other continents. Carbon and lead isotopes, in combination with oxygen and strontium isotopes, provide the most useful information for identification of local vs foreigner status. In particular, high‐precision Pb isotopes show a distinct “Bulgarian” range; however, it is possible that individuals from other countries in Eastern Europe and/or central to western Asia could have overlapping isotopic values. Additional high‐precision multi‐isotope data from modern humans from different regions in the world are required to transition from speculative to more quantitative estimation of a geographical place of origin for unidentified human remains.     

Identification in blood stains through DNA typing with C4 and HLA-DR probes

A restriction fragment length polymorphism analysis using double digestion of DNA preparations with XbaI and BglII restriction enzymes and hybridization with C4 and HLA-DR probes is described. The typing conditions selected reveal extensive individual variation in both C4 and DR gene regions. In our panel of 46 unrelated individuals, 37 different phenotypic patterns were recognized when both probes were used, and preliminary discriminative power values of 0.865 and 0.914 were calculated for C4 and DR beta, respectively. The probability of a chance match using both systems is probably about 1.5.10(-2). The potential of this method for individual identification of blood stains was demonstrated on DNA prepared from 6-month-old dried blood stains from seven panel individuals. The seven individuals were all identified when comparing stain DNA patterns with panel control patterns. No RFLP pattern changes were observed following storage of blood stains. Based on these experiments with C4 and DR beta DNA typing under laboratory conditions, it is concluded that DNA typing with such probes may become a powerful tool in future stain identification analyses.     

Radiocarbon Analysis of Human Remains: A Review of Forensic Applications

Radiocarbon analysis of organic materials, with the comparison of values with those of the post‐1950 modern bomb curve, has proven useful in forensic science to help evaluate the antiquity of evidence. Applications are particularly helpful in the study of human remains, especially with those displaying advanced decomposition of soft tissues. Radiocarbon analysis can reveal if the remains relate to the modern, post‐1950 era and if so, also provide information needed to evaluate the death and birth date. Sample selection and interpretation of results must be guided by knowledge of the formation and remodeling of different human tissues, as well as contextual information and the approximate age at death of the individual represented. Dental enamel does not remodel and thus captures dietary radiocarbon values at the time of juvenile formation. Most other human tissues do remodel but at differing rates and therefore collectively offer key information relative to the estimation of the death date.     

Changes in perikymata and their significance to a postmortem dental identification

Perikymata are wavelike features that are normally found in the surface enamel of teeth. These structures are known to undergo regressive changes due to gradual attrition, mechanical abrasion, or chemical erosion. Forensic science has suggested that significance be placed on some forms of their loss as indicators of age, oral habits, and alignment of individual teeth. The dental identification of victims of a Vietnam War military aircraft crash is presented. The unusual pattern of perikymata change on two of the teeth suggests the antemortem existence of a removable partial denture. These findings support the exclusionary conclusions.     

Strontium and geolocation, the pathway to identification for deceased undocumented mexican border-crossers: a preliminary report

Much of the difficulty associated with identifying and repatriating deceased undocumented border-crossers stems from an inability to narrow down the search area to more probable options. Analysis of the isotopic variation in the tooth enamel of modern Mexican populations is currently underway at the University of California Santa Cruz. Using Thermo Ionization Mass Spectrometry, the pilot research analyzed strontium isotopes located in the donated permanent teeth of Mexican-born individuals of known origin from four states. The preliminary results reveal the formation of three distinctly significant regions in the data set. Using the technology outlined here, a map documenting the isotopic variation in modern Mexican tooth enamel is being complied to use for cross comparison with deceased border crossers of unknown origin.     

Evaluation of neodymium isotope analysis of human dental enamel as a provenance indicator using 1013 Ω amplifiers (TIMS)

Human provenance studies employing isotopic analysis have become an essential tool in forensic and archaeological sciences, with multi-isotope approaches providing more specific location estimates compared to single isotope studies. This study reports on the human provenancing capability of neodymium isotopes (¹⁴³Nd/¹⁴⁴Nd), a relatively conservative tracer in the environment. Neodymium isotope ratios have only recently been determined on human remains due to low concentrations in human dental enamel (ppb range), requiring thermal ionisation mass spectrometry (TIMS) using 10¹³ Ω resistors. Dental elements (third molars) from 20 individuals born and raised in the Netherlands were analysed for Nd concentration (n = 12) and Nd isotope ratios (n = 15). The geological control on Nd isotope composition was examined using coupled Nd-Sr isotope analysis of the same third molar. Teeth from different geological environments were also analysed (Caribbean, Columbian, and Icelandic, n = 5). Neodymium elemental concentrations in dental elements ranged between 0.1 and 7.9 ppb (median 0.5 ppb). The Dutch ¹⁴³Nd/¹⁴⁴Nd ratios of the provinces of Limburg and Friesland were between 0.5118 and 0.5121, with Dutch ⁸⁷Sr/⁸⁶Sr ratios in agreement with the previously established local range (0.708–0.710). The current findings were compared to previously published results on Nd concentration and composition from Dutch individuals. The concentration of Nd and ¹⁴³Nd/¹⁴⁴Nd ratios were weakly correlated (R² = 0.47, n = 17) in Dutch human dental enamel. The majority (n = 25, 83.3%) of individuals had Nd and Sr isotope values isotopically indistinguishable from the geological environment in which their third molars formed and mineralised. However, the Nd isotope ratios of the Icelandic individual and several Dutch individuals (n = 4) suggested that Nd in enamel is not solely influenced by geological environment. In order for neodymium isotopes to be quantitatively applied in forensic and archaeological settings further analyses of individuals from various geographical regions with well-defined dietary Nd isotope data are required.     

Legal Paternalism and Legal Moralism: Devlin, Hart and Ten*

Abstract
H. L. A. Hart in his Law, Liberty, and Morality (1963) defended the view that legal paternalism and legal moralism can be clearly distinguished from each other. Hart also stated that while legal moralism is always unacceptable, paternalistic laws are often justifiable. In this paper it is argued that Hart held the right view for the wrong reasons. Hart defended legal paternalism by claiming, against J. S. Mill, that for various psychological reasons individuals do not know their own interests best. It will be shown in the paper that if this view is taken, it is impossible to reject legal moralism. The fact that paternalism is sometimes justifiable while moralism is not can be more firmly founded on a distinction made by C. L. Ten (1971). Ten's point is that in matters which concern only the individuals themselves, their actions cannot be legitimately restricted by appeals to the consequences of their action alone. Paternalistic control can be justified only if the decision-making abilities of the controlled individual are temporarily diminished.     

Precision and reliability of pulp/tooth area ratio (RA) of second molar as indicator of adult age

This paper discusses a method for assessing adult age based on the relationship between age and measurement of the pulp/tooth area ratio (RA) of the second molar teeth. The sample consisted of 312 Italian white Caucasian patients (135 men, 177 women) aged between 14 and 24 years. Orthopantomograph samples (OPGs) were analyzed by the same observer and calibrated by kappa statistics. Probabilities of an individual being older than 18 years of age (adult age) were derived using measurements of the ratio pulp/tooth area (RA) of the second molar teeth and the dichotomized stages of third molar development (Tm) as explanatory variables. These results were exploited to establish a threshold value to assign an individual to juvenile or adult age. A cut-off value of RA* = 0.088 was applied if Tm = 0 and RA* = 0.097 if Tm = 1. The sensitivity of this test was 91% and its specificity 94.5%. The proportion of individuals with correct classifications was 92%.     

Analysis of enamel rod end patterns on tooth surface for personal identification--ameloglyphics

Ameloglyphics is the study of enamel rod end patterns on a tooth surface. Our aim was to study the in vivo analysis of enamel rod end patterns on tooth surfaces for personal identification. In this study, the maxillary left canine and 1st premolar of 30 men and 30 women were included. The cellulose acetate peel technique was used to record enamel rod endings on tooth surfaces. Photomicrographs of the acetate peel imprint were subjected to VeriFinger Standard SDK v5.0 software for obtaining enamel rod end patterns. All 120 enamel rod end patterns were subjected to visual analysis and biometric analysis. Biometric analysis revealed that the enamel rod end pattern is unique for each tooth in an individual. It shows both intra- and interindividual variation. Enamel rod end patterns were unique between the male and female subjects. Visual analysis showed that wavy branched subpattern was the predominant subpattern observed among examined teeth. Hence, ameloglyphics is a reliable technique for personal identification.