The region includes the four independent countries of Fiji, Vanuatu, Solomon Islands, Papua New Guinea, as well as the French special collectivity of New Caledonia, and parts of Indonesia – particularly Western New Guinea. Most of the region is in the Southern Hemisphere, with only a few small northwestern islands of Western New Guinea lying in the Northern Hemisphere.
The name Melanesia (in French Mélanésie) was first used by Jules Dumont d'Urville in 1832 to denote an ethnic and geographical grouping of islands whose inhabitants he thought were distinct from those of Micronesia and Polynesia.
The concept among Europeans of Melanesia as a distinct region evolved gradually over time as their expeditions mapped and explored the Pacific. Early European explorers noted the physical differences among groups of Pacific Islanders. In 1756 Charles de Brosses theorized that there was an "old black race" in the Pacific who were conquered or defeated by the peoples of what is now called Polynesia, whom he distinguished as having lighter skin.:189–190 In the first half of the nineteenth century Jean Baptiste Bory de Saint-Vincent and Jules Dumont d'Urville identified Melanesians as a distinct racial group. :165
Over time, however, Europeans increasingly viewed Melanesia as a distinct cultural, rather than racial, area. Scholars and other commentators disagreed on its boundaries, which were fluid. In the nineteenth century Robert Codrington, a British missionary, produced a series of monographs on "the Melanesians" based on his long-time residence in the region. In works including The Melanesian Languages (1885) and The Melanesians: Studies in Their Anthropology and Folk-lore (1891), Codrington defined Melanesia as including Vanuatu, Solomon Islands, New Caledonia, and Fiji. He did not include the islands of New Guinea because only some of its people were Melanesians. Like Bory de Saint-Vincent, he excluded Australia from Melanesia.:528 It was in these works that Codrington introduced the cultural concept of mana to the West.
Uncertainty about the delineation and definition of the region continues. The scholarly consensus now includes New Guinea within Melanesia. Ann Chowning wrote in her 1977 textbook on Melanesia that there is
no general agreement even among anthropologists about the geographical boundaries of Melanesia. Many apply the term only to the smaller islands, excluding New Guinea; Fiji has frequently been treated as an anomalous border region or even assigned wholly to Polynesia; and the people of the Torres Straits Islands are often simply classified as Australian aborigines.:1
In 1998 Paul Sillitoe wrote of Melanesia: "it is not easy to define precisely, on geographical, cultural, biological, or any other grounds, where Melanesia ends and the neighbouring regions ... begins".:1 He ultimately concludes that the region is
a historical category which evolved in the nineteenth century from the discoveries made in the Pacific and has been legitimated by use and further research in the region. It covers populations that have a certain linguistic, biological and cultural affinity – a certain ill-defined sameness, which shades off at its margins into difference.:1
Both Sillitoe and Chowning include the island of New Guinea in the definition of Melanesia, and both exclude Australia.
Most of the peoples in Melanesia have established independent countries, are administered by France or have active independence movements (in the case of West Papua). Many have recently taken up the term 'Melanesia' as a source of identity and empowerment. Stephanie Lawson writes that the term "moved from a term of denigration to one of affirmation, providing a positive basis for contemporary subregional identity as well as a formal organisation".:14 For instance, the author Bernard Narokobi wrote about the "Melanesian Way" as a distinct form of culture that could empower the people of this region. The concept is also used in geopolitics. For instance, the Melanesian Spearhead Group preferential trade agreement is a regional trade treaty among Vanuatu, Solomon Islands, Papua New Guinea, and Fiji.
The people of Melanesia have a distinctive ancestry. Along with the aboriginal inhabitants of Australia, the Southern Dispersal theory indicates they emigrated from Africa between 50,000 and 100,000 years ago and dispersed along the southern edge of Asia. The limit of this ancient migration was Sahul, the continent formed when Australia and New Guinea were united by a land bridge as a result of low sea levels. The first migration into Sahul came over 40,000 years ago. A further expansion into the eastern islands of Melanesia came much later, probably between 4000 and 3000 BC.
Particularly along the north coast of New Guinea and in the islands north and east of New Guinea, the Austronesian people, who had migrated into the area somewhat more than 3,000 years ago, came into contact with these pre-existing populations of Papuan-speaking peoples. In the late 20th century, some scholars theorized a long period of interaction, which resulted in many complex changes in genetics, languages, and culture among the peoples. This Polynesian theory, however, is somewhat contradicted by the findings of a genetic study published by Temple University in 2008. It found that neither Polynesians nor Micronesians have much genetic relation to Melanesians. It appeared that, having developed their sailing outrigger canoes, the ancestors of the Polynesians migrated from East Asia, moved through the Melanesian area quickly on their way, and kept going to eastern areas, where they settled. They left little genetic evidence in Melanesia and "only intermixed to a very modest degree with the indigenous populations there". Nevertheless, the study still found a small Austronesian genetic signature (below 20%) in some of the Melanesian groups who speak Austronesian languages, and which was entirely absent in Papuan-speaking groups.
Most of the languages of Melanesia are members of the Austronesian language family or one of the numerous Papuan languages, which is a geographical term covering many separate language families. By one count, there are 1,319 languages in Melanesia, scattered across a small amount of land. The proportion of 716 square kilometers per language is by far the most dense rate of languages in relation to land mass on Earth, almost three times as dense as in Nigeria, a country famous for its high number of languages in a compact area.
In addition to the many indigenous languages, pidgins and creole languages have developed, often from trade and cultural interaction centuries before European encounter. Most notable among these are Tok Pisin and Hiri Motu in Papua New Guinea. They are now both considered distinct creole languages. Use of Tok Pisin is growing. It is sometimes learned as a first language, above all by multi-cultural families. Other creoles include Solomon Islands Pijin, Bislama, Papuan Malay and other related languages.
A distinction is often made between the island of New Guinea and what is known as Island Melanesia, which consists of "the chain of archipelagos, islands, atolls, and reefs forming the outer bounds of the sheltered oval-shaped coral sea".:5 This includes the Louisiade Archipelago (a part of Papua New Guinea), the Bismarck Archipelago (a part of Papua New Guinea and Solomon Islands), and the Santa Cruz Islands (a part of the country called Solomon Islands). The country of Vanuatu is composed of the New Hebrides island chain (and in the past 'New Hebrides' has also been the name of the political unit located on the islands). New Caledonia is composed of one large island and several smaller chains, including the Loyalty Islands. The nation of Fiji is composed of two main islands, Viti Levu and Vanua Levu, and smaller islands, including the Lau Islands.
The names of islands in Melanesia can be confusing: they have both indigenous and European names. National boundaries sometimes cut across archipelagos. The names of the political units in the region have changed over time, and sometimes have included geographical terms. For example, the island of Makira was once known as San Cristobal, the name given to it by Spanish explorers. It is in the country Solomon Islands, which is a nation-state and not a contiguous archipelago. The border of Papua New Guinea and Solomon Islands separates the island of Bougainville from nearby islands like Choiseul, although Bougainville is geographically part of the chain of islands that includes Choiseul and much of the Solomons.
In addition to the islands mentioned above, there are many smaller islands and atolls in Melanesia. These include:
Several Melanesian states are members of intergovernmental organizations. Papua New Guinea, Solomon Islands, and Vanuatu are members of the Commonwealth of Nations. Fiji, Papua New Guinea, Solomon Islands, and Vanuatu are also members of the Melanesian Spearhead Group.
Melanesians were found to have a mysterious third archaic Homo species along with their Denisovan (3–4%) and Neanderthal (2%) ancestors in a genetic admixture with their otherwise modern Homo sapiens sapiens genomes. Their most common Y-chromosome haplogroup is M-P256.
The high occurrence of blond hair is due to a specific random mutation, so DNA and phenotype for blonds appeared at least twice in human history.