Near Oceania When the naturalist
Alfred Russel Wallace explored
Nusantara, he drew attention to fundamental biological differences between the
Australia-New Guinea region and Southeast Asia. The boundary between the Asian and Australian faunal regions consists of a zone of smaller islands bearing the name of
Wallacea, in honor of the co-discoverer of the theory of
natural selection. Wallace speculated that the key to understanding these differences would lie in "now-submerged lands, uniting islands to continents" (1895). At several intervals during the
Pleistocene, the sea surface was 130 metres below the current sea level, joining the
Aru Islands,
New Guinea,
Tasmania, and some smaller islands to the
Australian mainland. Biogeographers referred to this enlarged Greater Australian continent as "
Sahul" (Ballard, 1993) or "Meganesia". West of Wallacea, the vast
Sunda Shelf was also exposed as dry land, greatly extending the Southeast Asian mainland to include the
Greater Sunda Islands of
Sundaland. However, the islands of Wallacea (primarily
Sulawesi,
Ambon,
Ceram,
Halmahera, and the
Lesser Sunda Islands) always remained an island world, imposing a barrier to the dispersal of terrestrial
vertebrates, including early
hominids. To the north and east of New Guinea, the islands of Near Oceania (the
Bismarck Archipelago and the Solomons) were likewise never connected to Sahul by dry land, for deep-water trenches also separate these from the Australian
continental shelf. Human colonization of this region was most likely effected during the interval between 60,000 and 40,000 years ago, although some researchers hypothesized possible earlier dates. Regardless, even during the period when the sea level was at its lowest, there were always significant open-water gaps between the islands of Wallacea, and therefore, the arrival of humans into Sahul necessitated over-water transport. This was also the case of the expansion of humans beyond New Guinea into the archipelagoes of Near Oceania. According to Spriggs (1997): :The settlement of
Manus — in the
Admiralty Islands — may represent a real threshold in voyaging ability as it is the only island settled in the
Pleistocene beyond the range of one-way intervisibilty. Voyaging to Manus involved a blind crossing of some 60–90 km in a 200–300 km voyage, when no land would have been visible whether coming from the north coast of Sahul or
New Hanover at the northern end of
New Ireland. These would have been tense hours or days on board that first voyage and the name of
Pleistocene Columbus who led this crew will never been known. The target arcs for Manus are 15° from New Hanover, 17° from
Mussau and 28° from New Guinea. (Matthew Spriggs,
The Island Melanesians, Oxford: Blackwell, 1997)
Remote Oceania The islands of Remote Oceania were not settled until around the
12th century BC, when seafaring navigators of the Austronesian
Lapita culture settled in the region. Paleogenetic analyses indicated that the original settlers of the islands originated from Neolithic populations in
Taiwan and the northern
Philippines, corresponding to the early
expansion of Austronesian peoples. Many contemporary populations of western Remote Oceania nonetheless have a strong Papuan ancestry linked to a second expansion that began around the
1st millennium BC. ==See also==