Reconstructing physical activities in ancient humans has long been pursued in bioarchaeology to understand our history and development. Entheseal changes (EC)––variations to muscle, tendon, and ligament attachment sites on bone––have been used in bioarchaeology since the 1980s to reconstruct activities in past populations such as changes in mobility, subsistence strategy, and gendered division of labour. EC research is based on bone functional adaptation, where bone responds to mechanical stress on entheses through bone formation or destruction in varying degrees of expression. However, the relationship between EC and activity is more complex than simple cause-and-effect, as it involves multiple confounding variables, which can affect EC morphology. This article addresses the use of EC research in bioarchaeology through two parts: Part 1 defines entheses and EC, including observational and quantitative methods developed in bioarchaeology to study EC. Part 2 will summarize the main known factors that influence EC beyond activity such as age, sex, and body size. The article concludes with a discussion of varying benefits and limitations to EC research in bioarchaeology including the use of archaeological samples, historical collections, and animal experimental models. Overall, EC research can be difficult to link with activity due to its multifactorial etiology, challenges of efficacy in developing methods, and limitations of working with human remains. However, recent studies are showing more positive results, demonstrating the usefulness of EC as a way to reconstruct activity.

Morphological changes in the skeletons of working animals such as reindeer, horse, and cattle have long been observed and documented in the archaeological record. Activities such as riding, carrying cargo on their backs, and pulling vehicles like sleds and ploughs throughout an animal’s life history cause alterations and variations to skeletal tissue. Such alterations include paleopatho­logical lesions, entheseal changes (EC)—alterations in muscle, tendon, and ligament attachment sites on bone—and variations in cross-sectional bone geometry (CSBG). These clues are helpful for reconstructing human-animal relationships in faunal remains of our archaeological past. However, other factors influence the morphological appearance of skeletal tissue besides working activities, such as age, sex, body size, nutrition, genetics, environmental factors, and management by human caretakers. This article explores how paleopathological lesions, EC, and CSBG in faunal skeletal remains are examined to reconstruct working activity and changes to human-animal rela­tionships in the archaeological record. In particular, we discuss two primary topics of inquiry: (1) a review of paleopathological identifiers in working animals such as cattle, horse, camel, and rein­deer; and (2) how EC and CSBG are understood in terms of bone functional adaptation, and their application in working and non-working animals such as reindeer and horse. Next, we analyze each topic highlighting their benefits and limitations, including how they contribute to archeolog­ical understandings of human-animal relationships in the past, as well as their implications for future research.