Or did they evolve by natural or 'social' selection, during the millennia in which the descendants of those pioneers remained isolated, reproductively, from neighbouring islanders? Nothing now known about Bougainville’s physical environment can support an argument for the natural selection of its peoples' distinctively black pigmentation; therefore a case might be made for social selection, namely an aesthetic (and hence reproductive) preference for black skin. Dutch explorers Willem Schouten and Jacob Le Maire were the first Europeans to sight present-day Bougainville, skirting Takuu Atoll and Nissan Island in 1616. In 1643, another Dutch expedition led by Abel Tasman was the first to make contact with the islanders and describe their appearance. There was no further European contact until 1767, when British naval officer Philip Carteret visited and named the Carteret Islands. Carteret was also the first European to see Buka Island. The following year, Frenchman Louis Antoine de Bougainville sailed along the east coast of Bougainville Island, which bears his name. He also gave Buka Island its name, after a word that was repeatedly called out to him from canoes originating from the island. On 10 April 1886, two years after the establishment of German New Guinea, the United Kingdom and Germany agreed to divide the Solomon Islands archipelago into spheres of influence. As a result of this agreement, the islands of Buka, Bougainville, Choiseul, Santa Isabel, Ontong Java, the Shortland Islands, and part of the Florida Islands were placed under a German protectorate ("Schutzgebiet"), which was formally established on 28 October 1886 by the commander of . On 13 December, Kaiser Wilhelm I granted the New Guinea Company a charter to govern the protectorate in accordance with the existing arrangements for German New Guinea. The remainder of the archipelago became the British Solomon Islands Protectorate, which was not formally established until 1893. The present-day boundary between Bougainville and the country of Solomon Islands was established following the Tripartite Convention of 1899, which saw some of the northern islands ceded to the UK in exchange for German control over Western Samoa. The Shortlands, Choiseul, Santa Isabel, and Ontong Java were included in the cession. The Northern Solomons were initially grouped with the Bismarck Archipelago for German administrative purposes. The first official visit from the German administration did not occur until November 1888. The acting administrator Reinhold Kraetke arrived accompanied by an imperial judge, a company manager, a visiting German journalist, a missionary, and a local merchant Richard Parkinson who had been recruiting labourers from the area for several years.