Evolution of two human skeletal markers of the squatting position: a diachronic study from antiquity to the modern age.

Some human skeletal features that were produced through the actions of their bearers during life allow the reconstruction of postures. These can be typical of population groups. For example, tibial retroversion and lateral squatting facets are two skeletal markers closely related to the habit of squatting. The facets and the retroversion are induced by pressure and traction as a consequence of the hyperdorsiflexion of the knees and ankles. The examination of 543 tibiae and tali from French and American archaeological series, and dating between the 1st-20th century AD, reveals changes in squatting posture over time. This study shows that tibial retroversion tends to be a "precocity indicator" of the adoption of this posture, while the lateral squatting facet shows the intensity or regularity of the use of this posture. The results indicate that squatting was a regular behavior used until the end of the Middle Ages, and after this period a progressive decrease occurs. This tendency may be explained by different lifestyles in different time periods.