In the mid-19th century, evolutionary biologist Alfred Russel Wallace pinpointed a major biogeographic boundary now known as the Wallace Line. Pigs represent one notable exception to the rules of the Wallace Line. There are populations of pigs on both sides of the Wallace Line, extending across Southeast Asia into New Caledonia, Vanuatu, and remote Polynesia. About 4,000 years ago, the introduction to pigs accelerated, when early agricultural communities transported domestic pigs across Island Southeast Asia. On the Komodo islands, the domestic pigs hybridized with the warty pigs that were brought over by people from Sulawesi thousands of years earlier.