The fluctuating asymmetry of medieval and modern human skulls.

The analysis of fluctuating asymmetry (FA) allows for estimating the influence of stress factors on human development and allows to evaluate resistance to stress. FA is often used as a marker of prenatal stress. The aim of this work is to estimate the symmetry of skulls from selected historic human populations and to analyse changes in their morphology which have taken place over centuries. The studied material consisted of two skull samples - a modern sample containing 82 skulls and a medieval sample of 77 skulls from Gródek on the Bug River. Radiographs were taken in postero-anterior (P-A) and base projections. Images were scanned and calibrated by means of MicroStation 95 Academic Edition software. Measurements of the skull images were used to estimate FA. All data were analysed statistically. The skulls in both samples showed asymmetry. The levels of FA varied in different skull regions. A high level of FA in the calvaria and a low asymmetry for the facial part of skull is characteristic of modern skulls. In medieval skulls these relations are inverted. The higher value of FA in modern skulls is an evidence of a higher level of developmental stress in the modern population as well as of its lesser abilities to resist stress.