Domestication in the Neolithic
Archaeological evidence shows that pigs were domesticated from wild boar in the Near East in or around the Tigris Basin, being managed in a semi-wild state much as they are managed by some modern New Guineans. There were pigs in Cyprus more than 11,400 years ago, introduced from the mainland, implying domestication in the adjacent mainland by then. Pigs were separately domesticated in China, starting some 8,000 years ago. In the Near East, pig husbandry spread for the next few millennia. It reduced gradually during the Bronze Age, as rural populations instead focused on commodity-producing livestock, but it was sustained in cities.
Domestication did not involve reproductive isolation with population bottlenecks. Western Asian pigs were introduced into Europe, where they crossed with wild boar. There appears to have been interbreeding with a now extinct ghost population of wild pigs during the Pleistocene. The genomes of domestic pigs show strong selection for genes affecting behavior and morphology. Human selection for domestic traits likely counteracted the homogenizing effect of gene flow from wild boars and created domestication islands in the genome. Pigs arrived in Europe from the Near East at least 8,500 years ago. Over the next 3,000 years they interbred with European wild boar until their genome showed less than 5% Near Eastern ancestry, yet retained their domesticated features.
DNA evidence from subfossil remains of teeth and jawbones of Neolithic pigs shows that the first domestic pigs in Europe were brought from the Near East. This stimulated the domestication of local European wild boar, resulting in a third domestication event with the Near Eastern genes dying out in European pig stock. More recently there have been complex exchanges, with European domesticated lines being exported, in turn, to the ancient Near East. Historical records indicate that Asian pig breeds were reintroduced to Europe during the 18th and early 19th centuries.
Domesticated pigs were among the three main domesticated animals (with chickens and dogs) carried by the seaborne Neolithic migrations of the Austronesian peoples to Island Southeast Asia and Oceania, around 4000 years ago. Most free-living and domesticated pigs from the Philippines to Hawaiʻi are descended from domesticated pigs (Sus scrofa) introduced by Austronesians from southeastern China and Taiwan via the Philippines. Other species of pigs (Sus celebensis, Sus barbatus, Sus cebifrons, and Sus verrucosus), also spread much earlier from Mainland Southeast Asia to Island Southeast Asia west of the Wallace Line, via natural means or earlier (non-Austronesian) hunter-gatherer groups. Many of these endemic pigs later hybridized with the S. scrofa carried by Austronesians. Early archaeological specimens of pigs in Near and Remote Oceania exhibit no genetic admixture with local wild populations, maintaining a distinct, introduced mitochondrial lineage (the "Pacific Clade") that remained genetically isolated during the initial settlement period. There is evidence that humans have moved pigs around the Asia-Pacific for at least 50,000 years.
