Tanzania, a democratic country larger in surface area than Texas, is located on Africa's eastern coast, along the Indian Ocean. It was created through the union of Tanganyika and Zanzibar in 1964. Because of its numerous lakes, approximately 22,800 square miles of Tanzania's territory consists of inland water. It is in this country that Dr. Louis B. Leakey changed evolutionary theory with the discovery of a 1.75-million-year-old Zinjanthropus skull at Olducai Gorge. The imposition of European rule, Arab influence, and the history of the movement and mixture of African ethnic groups for at least the last two millennia has implied adaptation to both new physical and human social arrangements for the native peoples in this country. For Tanzanians, kinship forms the basis for interpersonal relations and group formation, a pattern that persisted throughout the earlier period and continues to the present time. For individuals, kin ties through parents and by marriage define one's rights, obligations, and opportunities. For the last three decades, Tanzania has experimented with a cooperative socioeconomic system, Ujamaa, based on indigenous social structures and socialist economics and largely drafted by the country's first president, Julius K. Nyerere.