Scoliosis are "captured", meaning that they are held fast between the ilium bones of the pelvis. Compared to humans, Old World monkeys have far larger erector spinae muscles, which are the muscles which hold the spine steady. These factors make the lumbar spine of most primates less flexible and far less likely to deviate than those of humans. While this may explicitly relate only to lumbar scolioses, it is possible that small imbalances in the lumbar spine could precipitate thoracic problems as well. Scoliosis may be a byproduct of strong selection for bipedalism. For a bipedal stance, a highly mobile, elongated
Scoliosis in life secondary to degenerative (may or may not be associated with aging) changes. This is a type of deformity that starts and progresses because of the collapse of the vertebral column in an asymmetrical manner. People who initially present with scoliosis undergo physical examination to determine whether the deformity has an underlying cause and to exclude the possibility of underlying condition more serious than simple scoliosis. The person's gait is assessed, with an exam for signs of other abnormalities (e.g., spina bifida as evidenced by a dimple, hairy patch, lipoma, or hemangioma). A thorough neurological examination is also performed,