Asymmetry and activity‐related change in the male humerus

Some previous studies of activity‐related change in the human skeleton have been of doubtful validity because specific changes have been related to particular tasks. Claims to establish such relationships have often concentrated on the development of entheses. Such work is marred by the incorrect assumption that muscles work in isolation in the performance of a single activity. In addition, normal skeletal asymmetry is often ignored, as is age and sex. In the present work, paired humeri of males from two medieval British sites, Norwich and Henry VIII's flagship, the Mary Rose , were compared using a series of measurements. Comparison of left and right sides demonstrated that humeral asymmetry decreases with age. Comparison of the sites showed that the Norwich males were more asymmetric than those from the Mary Rose . All asymmetries exhibited a right‐sided dominance. The majority of the species is right‐handed: the Norwich males followed this trend. The general lack of asymmetry in the Mary Rose males suggests that they were using their arms more equally. When left and right sides were compared directly, a new measurement of the greater tubercle (where three muscles insert) and measurement of the diameter of the head demonstrated that the Mary Rose males had significantly larger dimensions of the left shoulder than the Norwich males. These results extend earlier work, which had suggested a correlation between the use of heavy medieval longbows and os acromiale . Statistical comparison of the sites demonstrated that such work can indicate patterns of activity but not individual occupations.