Osteoarthritis (OA) or degenerative joint disease (DJD) is the most common disorder affecting the joints, affecting 10 percent of men and 18 percent of women over 60 years of age worldwide. OA results from the progressive breakdown of the articular cartilage and from a suite of degenerative and reactive patterns involving various tissues. Such patterns result in modifications of the joint architecture and of the joint segments which are variably visible radiologically and on dry bone. Due to its link with biomechanical stress, OA is studied extensively in paleopathology and bioarchaeology in order to reconstruct general and specific levels of physical activity in past populations. However, the etiological relevance of other factors besides physical activity (e.g. age, sex, and genetics) suggests the need for caution in such biocultural reconstructions, stressing at the same time the value of clinical studies for a better understanding of OA in bioarcheology and paleopathology.