Analysis of Radiocarbon, Stable Isotopes and DNA in Teeth to Facilitate Identification of Unknown Decedents

Abstract

The characterization of unidentified bodies or suspected human remains is a frequent and important task for forensic investigators. However, any identification method requires clues to the person’s identity to allow for comparisons with missing persons. If such clues are lacking, information about the year of birth, sex and geographic origin of the victim, is particularly helpful to aid in the identification casework and limit the search for possible matches. We present here results of stable isotope analysis of 13C and 18O, and bomb-pulse 14C analyses that can help in the casework. The 14C analysis of enamel provided information of the year of birth with an average absolute error of 1.8±1.3 years. We also found that analysis of enamel and root from the same tooth can be used to determine if the 14C values match the rising or falling part of the bomb-curve. Enamel laydown times can be used to estimate the date of birth of individuals, but here we show that this detour is unnecessary when using a large set of crude 14C data of tooth enamel as a reference. The levels of 13C in tooth enamel were higher in North America than in teeth from Europe and Asia, and Mexican teeth showed even higher levels than those from USA. DNA analysis was performed on 28 teeth, and provided individual-specific profiles in most cases and sex determination in all cases. In conclusion, these analyses can dramatically limit the number of possible matches and hence facilitate person identification work.

Radiocarbon dating of seized ivory confirms rapid decline in African elephant populations and provides insight into illegal trade

“…Atmospheric 14 C (as 14 CO 2 ) enters the terrestrial biosphere by photosynthesis; 14 C is subsequently incorporated into herbivore tissues as the animals ingest plants for food. The bomb- 14 C signal has been used in human forensic studies (17)(18)(19)(20)(21) and has also been used previously to date ivory and other animal tissues including hair, horn, and tooth enamel (22)(23)(24)(25). Prior work on 14 C dating of ivory has used the atmospheric 14 C/ 12 C historical record to determine the calibrated age of samples.…”

The impact of loading, unloading, ageing and injury on the human tendon

“…; Alkass et al . ). Using racemization, it has been demonstrated that the half‐life of horse tendon is around 200 years in high strain, injury‐prone superficial digital flexor tendon, and far less (∼34 years) in low strain and rarely injured common digital extensor tendon (Thorpe et al .…”

14C Analysis of protein extracts from Bacillus spores

“…The average F 14 C of the soluble fraction of control Bt ken spores was 1.078 ± 0.032 (1 SD) for a chronological uncertainty of ± 6 years. This is more variability than typically seen in bomb pulse dating [22–27,31,33,37] and was attributed to initial use of a shared lyophilizer to dry control spore preparations. Pump oil and solvents can contaminate samples with 14 C-free carbon, causing depressions in F 14 C by adding carbon mass that is devoid of 14 C. As noted, some spore samples were not miscible in initial extraction components indicating significant surface contamination, however, in subsequent steps slurries were obtained.…”

“…Additionally, the 14 C bomb-pulse has been used for forensic dating organic material and teeth of recent origin [10,22–31]. Although bomb pulse dating was not developed using microorganisms, the same general principles of 14 C sample definition and analysis that apply to higher-order organisms also apply to heterotrophic bacteria.…”