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
Supernumerary body part two or more different populations of genetically distinct cells that originated in different zygotes that have merged; anatomical structures are typically mixed depending on which cells are prevalent in different body parts, for example plants can have two different types of flowers. A mosaic is a genetic anomaly similar in nature and effects to a chimera: genetically different populations of cells within one organism, originated from some propagated mutation of a single cell rather than from outside sources. In Hindu mythology, additional limbs and heads are considered a sign of power. In Greek mythology, Artemis, the goddess of fertility, was