Papua New Guinea comprises the eastern half of the island of New Guinea and several hundred islands to the east and north. The land area is 463,000 square kilometers and the population of 3.6 million is largely Melanesian. Resources include plentiful arable land, extensive forests, rich mineral deposits, and hydroelectric potential. However, much of the terrain is mountainous, which makes travel and communications difficult. The population density is only eight persons per square kilometer and substantial areas of the interior remain unexplored. There are some 700 local languages, and allegiances are closely tied to villages. While social obligations differ among kinship groups, most land is communally owned and members assist others in need. For many inhabitants, contact with the modern world is recent and access to health, education, and other social facilities remains limited. Life expectancy is 52 years and poverty is more pronounced than in other Pacific island countries.