Dani tribesman in the Baliem Valley
The current population of the island of New Guinea is about 7.1 million people. Many believe human habitation on the island has been dated to as early as approximately 40,000 B.C., and first settlement possibly dated back to 60,000 years ago has been proposed. The island is presently populated by very nearly a thousand different tribal groups and a near-equivalent number of separate languages, which makes New Guinea the most linguistically diverse area in the world. Ethnologue 14th edition lists 826 languages of Papua New Guinea and 257 languages of Irian Jaya, total 1073 languages, with 12 languages overlapping. They fall into one of two groups, the Papuan languages and the Austronesian languages. The separation was not merely linguistic; warfare among societies was a factor in the evolution of the men's house: separate housing of groups of adult men, from the single-family houses of the women and children, for mutual protection against the other groups. Pig-based trade between the groups and pig-based feasts are a common theme with the other peoples of southeast Asia and Oceania. Most societies practice agriculture, supplemented by hunting and gathering.