The Iatmul are a large ethnic group of about 10,000 people inhabiting some two-dozen politically autonomous villages along the middle Sepik River in Papua New Guinea. The communities are roughly grouped according to dialect of the Iatmül language as well as sociocultural affinities. The Iatmul are best known for their art, men's houses, male initiation, elaborate totemic systems, and a famous ritual called naven, first studied by Gregory Bateson in the 1930s. More recently, the Iatmul are known as a location for tourists and adventure travelers, and a prominent role in the 1988 documentary film Cannibal Tours.
In Iatmul legend, the original condition of the world was a primal sea. A wind stirred waves, and land surfaced. A large pit opened, and out emerged the first generation of ancestral spirits and culture-heroes. The ancestors then embarked on a series of mythic-historic migrations. Where they trod, land appeared. Along these routes, the ancestors created the world through naming. Literally, they named all the features of the world into existence—trees, mountains, stars, winds, rains, tributaries, villages, actions, virtually everything in the world. These names are called totemic names. They are claimed by specific patrilineal groups (clans, lineages, and brances). Totemic names are magical, and form the basis for the religious system.
According to the Iatmul, the primal pit is located near the Sawos-speaking village of Gaikarobi. After emerging from the pit, most ancestors travelled to the village of Shotmeri.
The word "Iatmul" was coined by Gregory Bateson during his initial period of anthropological research among the language group in the late 1920s. In his 1932 article in the journal Oceania, Bateson wrote that he "adopted the name Iatmul as a general term for the people. But I doubt whether I am right in so doing." In Mindimbit village, he reported, local people referred to the entire linguistic group with the compound phrase Iatmul-Iambonai. The word Iambon (pronounced Yambon) referred then, and still does, to the upper-most Iatmul-speaking village along the river. Iatmul referred only to a single, small clan. The use of the word Iatmul, then, to signify the entire group, was Bateson's convention, and it thereafter gained anthropological and wider currency. However, the term is rarely used by Iatmul speakers. In fact, Iatmul speakers rarely have reason to refer to the entire language group. The Iatmul are not a centralized tribe. They never act politically, socially, or economically as a single unit. Villages are autonomous. People tend to self-identify not as Iatmul or, as they sometimes say, Iatmoi, but in terms of their clan, lineage, village, or sometimes just the colonial-era regional term, Sepik.