Nouvelles données sur l’édification des molaires et l’estimation de l’âge dentaire des enfants par imagerie médicale et 3D : apports et perspectives

Are the identified collections of immature skeletons dating from the Industrial Revolution good references for paleoauxological studies? Cases studies from England & France

OBJECTIVE

Skeletal collections of immature individuals identified by age and sex serve as reference material for studying development in past populations. Several of these collections were established during the Industrial Revolution (IR), a period known for its difficult living conditions in industrial cities. We question if these collections represent useful comparisons from which to explore the natural history of human growth.

MATERIALS

Immature individuals from two skeletal collections contemporaneous to the IR period were studied: 71 children from the Spitalfields (UK) and 108 from the Strasbourg (F) collections. Among them we selected mandibles of individuals aged from 0 to 30 months, representing 32 and 52 individuals, respectively.

METHODS

We scored the dental development of first and second left deciduous molars according to (Moorrees et al., 1963) stages, from X-rays (Spitalfields) or CT-scans (Strasbourg) data and compared it with the modern reference pattern from the Lewis Growth Records by covariance analysis (ANCOVA).

RESULTS

Statistical differences exist in the dental development timeline between the 3 samples. This mainly concerns a delay in the root formation in IR samples that related to post-natal living conditions.

CONCLUSIONS

The delay in dental development timeline suggests that growth processes were impacted during IR in England and France, probably due to stressful living conditions.

SIGNIFICANCE

keletal collections dating from the IR period in Europe might be not the most appropriate referencesl for studying the natural history of human growth.

LIMITATIONS

This study focus on dental development only.

SUGGESTIONS FOR FURTHER RESEARCH

Exploring the skeletal growth pattern in other skeletal collections, pre or post-dating the IR, is advised.

A Non-Destructive Method for Distinguishing Reindeer Antler (Rangifer tarandus) from Red Deer Antler (Cervus elaphus) Using X-Ray Micro-Tomography Coupled with SVM Classifiers

Over the last decade, biomedical 3D-imaging tools have gained widespread use in the analysis of prehistoric bone artefacts. While initial attempts to characterise the major categories used in osseous industry (i.e. bone, antler, and dentine/ivory) have been successful, the taxonomic determination of prehistoric artefacts remains to be investigated. The distinction between reindeer and red deer antler can be challenging, particularly in cases of anthropic and/or taphonomic modifications. In addition to the range of destructive physicochemical identification methods available (mass spectrometry, isotopic ratio, and DNA analysis), X-ray micro-tomography (micro-CT) provides convincing non-destructive 3D images and analyses. This paper presents the experimental protocol (sample scans, image processing, and statistical analysis) we have developed in order to identify modern and archaeological antler collections (from Isturitz, France). This original method is based on bone microstructure analysis combined with advanced statistical support vector machine (SVM) classifiers. A combination of six microarchitecture biomarkers (bone volume fraction, trabecular number, trabecular separation, trabecular thickness, trabecular bone pattern factor, and structure model index) were screened using micro-CT in order to characterise internal alveolar structure. Overall, reindeer alveoli presented a tighter mesh than red deer alveoli, and statistical analysis allowed us to distinguish archaeological antler by species with an accuracy of 96%, regardless of anatomical location on the antler. In conclusion, micro-CT combined with SVM classifiers proves to be a promising additional non-destructive method for antler identification, suitable for archaeological artefacts whose degree of human modification and cultural heritage or scientific value has previously made it impossible (tools, ornaments, etc.).