Developmental anomalies and South American paleopathology: A comparison of block vertebrae and co-occurring axial anomalies among three skeletal samples from the El Brujo archaeological complex of northern coastal Peru.

Though developmental anomalies have been noted for over a century in South American paleopathology, they have received less attention than other pathological conditions. When anomalies are reported, they tend to be unusual case studies or incidental findings. Paleopathological research should also consider anomalies from a population perspective, to broaden our understanding about the frequency of specific anomalies, and potentially offer insight into genetic relationships, cultural behavior, or environmental factors. This investigation compared block vertebrae and co-occurring postcranial axial anomalies among three skeletal samples reflecting an occupational sequence at the El Brujo Archaeological Complex of Peru. Block vertebrae demonstrate both considerable antiquity and persistence through time, though frequencies, vertebral level, and co-occurring anomalies varied by sex and cultural period. Among the Late Preceramic sample, the frequency of C2-C3 block vertebrae was highest and only seen among females, which may suggest familial influence, genetic isolation, and potentially matrilocality. The Moche sample demonstrated a moderate frequency of blocks, which in combination with the frequencies of other developmental anomalies, may suggest population continuity paired with an influx of new genes, demographic expansion, and possible cultural change with regard to postmarital residence. The Lambayeque sample demonstrated the lowest frequency of blocks and the highest frequency and greatest diversity of anomalies, which may suggest genetic continuity from the Moche, an expanded gene pool, broader opportunities for mate choice, and cultural change. It is hoped that this investigation will provide data for future comparisons and call attention to the need for the broader study of developmental anomalies in South America.