Cortical thickness and entheseal robusticity were used to measure the effects of activity and age in a group of 77 adult males from the site of Lisieux-Michelet in northern France. There was no known age at death for this population; age was determined using a series of osteological age estimation methods. Based on the currently available dates for this sample, the skeletal remains were primarily from the Late Roman Period (3rd-7th century AD).The adults were divided into three age categories based on these estimation results. Trends in cortical and entheseal development were measured within and between age categories. Results showed that entheses increased with age while cortical thickness decreased. However, low correlation between these two factors suggests that while entheseal robusticity responds to age, it is highly influenced by physical activity. Activity levels also affect cortical thickness which causes variation within age groups. A comparison of the Lisieux-Michelet entheseal and cortical measurements to both modern and archaeological populations indicated that these males engaged in physically demanding occupations. The degree of activity experienced by these individuals decreased during the middle adult years likely due to a shift to less physically demanding occupations. However, cortical and entheseal data suggest that the old adults from Lisieux-Michelet were not particularly frail and continued to be active even after the decrease in activity during the middle years. / Thesis / Master of Arts (MA)

[Truncated abstract] In this work a computer simulation program, similar to a finite element program, is used to study the relationship between skeletal tissue structure and function. Though other factors affect the shape of bone (e.g., genetics, hormones, blood supply), the skeleton adapts its shape mainly in response to the mechanical environment to which it is exposed throughout life. The specific relationship between the mechanical environment and the mechanical adaptation response of the skeleton is reviewed. Theories of mechanical adaptation are applied to the sites of tendon attachment to bone (entheses), the adaptation of generalised trabecular bone (i.e., Wolff’s Law of trabecular architecture), sesamoid bones that are often found where a tendon wraps around a bony pulley, and the internal trabecular structure of a whole bony sesamoid such as the patella. The relative importance of compression rather than tension in bone adaptation theories is still not fully understood. Some mechanical adaptation theories suggest that an overwhelming tensile stress at a skeletal location does not stimulate bone deposition, but would instead lead to bone resorption. The skeletal locations studied in this work were chosen because they have been proposed to be in tension. Computer simulations involving models are an ideal method to analyse the mechanical environment of a skeletal location. They are able to determine the mechanical stresses at, and the stress patterns around, complex biological situations. This study uses a two dimensional computer simulation program, Fast Lagrangian Analysis of Continua (Flac), to analyse the stress at the skeletal locations, and to test theories of mechanical adaptation over time by simulating physiological adaptation. The initial purpose of this study is to examine the stress in the skeletal tissue in generalised trabeculae, anatomical sites where a tendon wraps around a bony pulley, in the trabecular networks that fill the patella, and at tendon attachments. A secondary purpose, that follows directly from the first, is to relate the results of these initial stress analyses to existing and hypothetical skeletal tissue remodelling theories, to suggest how the complex skeletal structures might be generated solely in response to their mechanical environment. The term “remodelling” is used throughout this work to refer to mechanical adaptation of bone, usually at a surface of bone, rather than the internal regeneration of osteons (Haversion systems)