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.