Bilateral descent is only found among only a few groups in West Africa, India, Australia, Melanesia and Polynesia. Anthropoligists believe that a tribal structure based on bilateral descent helps members live in extreme environments because it allows individuals to rely on two sets of families dispersed over a wide area.
Under bilateral descent, every tribe member belongs to two clans, one through the father (a patriclan) and another through the mother (a matriclan). For example, among the Himba, clans are led by the eldest male in the clan. Sons live with their father's clan and when daughters marry they go to live with the clan of their husband. However inheritance of wealth does not follow the patrician but is determined by the matrician i.e. a son does not inherit his father's cattle but his maternal uncle's instead.