Identification. The Eipo and their neighbors live in the Daerah Jayawijaya of the Indonesian Province of Irian Jaya. The Eipo usually refer to themselves as "Eipodumanang," which means "the ones living on the banks of the Eipo River," but the term "Eipo" is sometimes extended to include the inhabitants of adjacent valleys. The term "Mek" (meaning water, or river) has been introduced by linguists and anthropologists to designate the fairly uniform languages and cultural traditions in this area.
Location. The Eipo inhabit approximately 150 square kilometers of land in the southernmost (upper) section of the Eipomek Valley, at approximately 4°25′-4°27′ S, 140°00′-140°05′ E. Settlements are found at elevations Between 1,600 and 2,100 meters, but surrounding mountain ranges reach 4,600 meters. The terrain is for the most part steeply incised. Anthropogenic grassland is found in a wide circle around the villages. Rain forest exists between the garden areas and covers the mountains above about 2,400 meters up to the tree line at 3,500 meters. Annual rainfall in 1975-1976 was 590 centimeters, with rain mostly falling daily in the afternoons and evenings. Temperatures range from about 11-13° to 21-25° C. Little seasonal change is to be observed, but the time of flowering of a particular tree ( Eodia sp.) is taken by the Eipo as a marker of certain feasts and other activities. In 1976 two severe earthquakes destroyed large areas of garden land and some villages; it is likely that similar catastrophes have occurred in the past.
Demography. The Eipo numbered close to 800 people in 1980; indications are that the population is growing.
Linguistic Affiliation. Eipo, of which there are three dialects, is a member of the Mek Family of Non-Austronesian languages, clearly separate from the Ok languages to the east, the Yali and Dani languages to the west, and languages spoken to the north and south. Local people traditionally understand—and, to a lesser extent, speak—one or two dialects or languages other than their own. Children usually learn their speech from their mothers (who, due to rules of exogamy, often come from different valleys) and often do not adopt the dialect spoken by the majority in a particular village. Bahasa Indonesia, unknown before the 1970s, is slowly gaining ground as a lingua franca.