When we speak of 'a kinship system' we mean social relations between persons expressed in the context of genealogical and affinal connections. Each term in the system is a symbol of a particular set of obligations, and two individuals call each other 'brother', for example, or 'cousin', is a shorthand way of indicating that they have certain specific reciprocal duties and claims. Morgan, the pioneer of kinship study, distinguished systems that merge lineal and collateral relatives from those that keep them apart. The Busama have a classificatory system closely resembling that of the people Morgan investigated, gated, the Iroquois Indians of North America. Usually a person speaks to his parents by the kinship terms but may refer to them either by the terms or by name. The system is internally consistent and, within certain limits, reflects social reality. Kinsfolk referred to by a single term are treated alike and those referred to by separate terms are treated differently.