Archaeological biological mineralizations: A cutting-edge multi-proxy investigation on kidney stones from the Argaric Bronze Age civilization

Two calculi retrieved at the archaeological site of La Almoloya (Murcia, Spain) dating to the Early Bronze Age were analyzed to evaluate their preliminary identification as kidney stones and to explore their pathological and social implications for the health status of a prehistoric complex society. The samples were examined through Scanning Electron Microscopy, X-Ray Fluorescence, X-Ray Diffraction, Fourier-Transform Infrared Spectroscopy and Micro Computed Tomography. Chemical results were combined with genetic and osteoarchaeological analysis. The recovered kidney stones are composed of primarily carbapatite, whitlockite and amorphous carbonated calcium phosphate. In one case, bacterial imprints were observed. Their chemical composition indicates an infectious origin; for one individual, the stone was probably formed due to a urinary tract infection, which was likely caused by a fracture of the ischiopubic ramus, which in turn can lead to urethral injuries. As urinary tract infections had persistent disabling effects on carrying out daily activities, the individuals involved would have benefited from social care. The study highlights the value of multidisciplinary approaches for identifying unusual bioarchaeological remains. Recovery of kidney stones in archaeological contexts remains challenging due to their small size and sedimentary resemblance; systematic screening of burial sediments could improve detection. DNA analysis of genetic material from pathogens preserved in kidney stones could help improve differential diagnosis and lead to a better assessment of the severity and persistence of the infection that caused the formation of the calculi.