Transcending human spondyloarthritis: Implications of the ecologic record from the Permian to the present

Spondyloarthropathy is recognized as far back as the Permian, 300 million years before present, increased in prevalence over geologic and modern time and is now essentially trans-mammalian in distribution. Four aspects allow spondyloarthropathy to be studied across phylogenetic lines and through time: Stability of disease characteristics and its spectrum, occurrence sufficiently early in life to for remains to be identified, absence of bias in skeletal preservation and lack of significant effect on organismal survival. Identified in mammal-like reptiles, dinosaurs and other more recent reptiles, it is with mammals that the disease became endemic. It strongly penetrated some early mammal lineages which were short-lived, in contrast to its geometric increase in population penetrance over geologic time. Prevalence increased seven fold in horses, rhinoceros and non-human primates and its current occurrence is independent of captive or free-ranging status. In addition to inflicting musculoskeletal morbidity, the disease is associated with behavior changes, some possibly related to interferon modulation. Spondyloarthropathy is considered a disease and rightly so, given its impact on mobility, health and behavior. However, it seems paradoxical that a phenomenon which has such negative effects would persist, let alone increase in population penetrance.