Daily Rest, Osteogenic Signals, and the Reconstruction of Human Activity Patterns From Skeletal Remains

Skeletal morphology is thought to provide a direct, if imprecise, means of inferring activity pattern in bioarchaeological and paleontological contexts. Given that bone is responsive to load histories, variation in daily activity is expected to impact the skeleton in predictable ways. Both the frequency and severity of daily loads have been shown to influence osteogenesis and, by extension, skeletal mass and robusticity. Consequently, population differences in skeletal robusticity have been treated as indicators of variation in daily activity duration and severity. However, evidence has also emerged that the timing and spacing of daily activity affect the transduction of osteogenic signals that promote bone apposition. In particular, periods of inactivity are necessary for the full benefit of daily loads to be realized as increases in bone mass. This paper uses simulation of empirically derived mathematical descriptors of bone mechanosensitivity to explore how patterning of rest intervals impacts the osteogenic potential of daily activity. These simulations offer three insights: (1) The timing of loads during daily activity has discernible osteogenic impacts, (2) maximum osteogenic potential is best achieved via relatively few but long‐duration periods of inactivity, and (3) there is substantial overlap in the osteogenic potential among different activity–inactivity profiles. This last insight suggests that granular reconstructions of past activity from skeletal remains will be challenging.