Bone microstructure and behaviour in “gracile” and “robust” adult males from the Medieval Period, Canterbury, UK.

ifferent types of activity can affect the morphology and strength of limb bones. This bone functional adaptation means that aspects of behaviour can be inferred in archaeological samples of modern humans. One popular methodological approach is to examine muscle attachment sites. However, this technique can be subjective. An alternative approach is to analyze bone microstructure. This latter method is more objective, because histological units directly linked to bone growth can be quantified. Here, we seek differences in bone microstructure between twenty age-matched adult ‘robust’ and ‘gracile’ male skeletons dated to the British Medieval period. \n \nSamples were selected based upon gross skeletal morphometry (37 bilateral postcranial measurements), muscle markers (55 bilateral postcranial sites), and femoral midshaft cross-section cortical thickness. Samples were then assigned as either ‘robust’ (n=10) or gracile (n=10). Following this, standard histological procedures were employed to produce thin sections of the posterior (P), anterior (A), lateral (L), and medial (M) femoral midshaft. Eight microscopic variables were compared between the groups. \n \nIntact osteon density (P:p=.013), fragmentary osteon density (P and M:p=.002, L:p=.010), osteon population density (P:p=.002, M:p=.003), Haversian canal area (A:p=.016, P:p=.028, M:p=.005, L:p=.002), Haversian canal diameter (A:p=.010, P:p=.023, M:p=.002, L:p=.007), osteon area (A:p=.002, P:p=.034, M:p=.001, L:p=.010), and osteocyte lacunae density (A:p=.011, P:p=.006, M and L:p=.000) differed significantly between gracile and robust males. Results indicate faster remodelling rates in robust individuals. Differences in behaviour are inferred between the two groups. A more active lifestyle involving excessive leg muscle use is inferred for the robust male group. Methodological suggestions are given.