The hierarchical social stratification has been an economically closed system, which historically has meant a marked inequality. Property and land has been exclusively owned by the upper caste members. Occupations and caste memberships are inherited. The Toucouleur castes have been endogamous, segregated and intermarriage has been rare. The clerics among Toucouleur like the Wolof people formed a separate group. The religious leaders were not necessarily endogamous nor an inherited post in Toucouleur people's long history, but it has been rare for lower caste people to become religious specialist, states Rüdiger Seesemann, as they were viewed as not sufficiently adhering to the "clerical standards of piety".