Evaluating possible metabolic stress in perinatal remains from 15th-century San Marcial de Rubicón: a multiproxy assessment of microporotic lesions

Diffuse microporotic lesions in perinatal skeletal remains are difficult to interpret because both biological and post-depositional processes may produce similar cortical alterations. This study evaluates diffuse microporotic lesions in two perinatal individuals (UE11 and UE25) recovered from a newly identified cemetery at San Marcial de Rubicón (Lanzarote, Canary Islands), the earliest European colonial settlement in the archipelago. Although ten individuals have been excavated from the cemetery, only these two perinates displayed extensive cortical porosity and are the focus of the present study. Scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), portable X-ray fluorescence (XRF), computed tomography (CT), and radiographic analyses were employed to characterise bone microstructure, elemental composition, sediment infiltration, and cortical surface morphology. Paleogenomic analysis was additionally performed to estimate the molecular sex of both individuals. SEM revealed abundant micropores and linear cortical disruptions, some containing angular sand grains, while elevated chlorine and sulfur concentrations and CT density values indicated substantial environmental alteration and sediment infilling. In UE11, the observed lesions are most consistent with aeolian abrasion, chemical dissolution, and post-depositional modification. In contrast, a subset of micropores in UE25 displayed smoother, rounded margins and limited sediment association, making them less readily explained by taphonomic processes alone. These findings demonstrate that interpretation of perinatal microporosity requires careful evaluation of taphonomic overprinting. While a definitive diagnosis cannot be established, some lesions in UE25 remain compatible with metabolic stress during late gestation or the early postnatal period. The study highlights the value of integrated microanalytical approaches for distinguishing environmental alteration from potential biological signals in fragile perinatal remains.