Diagnosis of diseases of bone, without benefit of soft tissue, in vivo observation, or blood component analysis requires the development of new criteria for diagnosis. Analyzing chimpanzee skeletal populations, applying such criteria (e.g., lesion character, distribution, radiologic appearance, and sex ratios), revealed a picture indistinguishable from human spondyloarthropathy. As Africa has been shown to manifest this condition in indigenous human, chimpanzee, and lowland gorilla populations, the possibility of a non-species specific etiology is suggested.