Archaeological evidence suggests that pigs were domesticated from wild boar around Turkey. There was also a separate domestication in China which took place about 8,000 years ago.
In the Near East, pigs were raised for thousands of years but gradually lost popularity during the Bronze Age, as rural populations focused instead on livestock that produced more commodities such as cattle, sheep, and goats. Pigs remained popular in more crowded areas.
DNA evidence from 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. Modern domesticated pigs have involved complex exchanges, with European domesticated lines being exported, in turn, to the ancient Near East. Historical records indicate that Asian pigs were introduced into Europe during the 18th and early 19th centuries.
In August 2015, a study looked at over 100 pig genome sequences to see how they were domesticated. They thought people had started with a few animals and were careful to keep them from mixing with wild swine. They found that pigs were domesticated separately in Turkey and China, with the pigs from Turkey introduced into Europe, where they crossed with wild boar. The study also found that despite interbreeding with wild pigs, domestic pigs were selected for behavior and physical traits. The study concluded that human selection probably counteracted the effect of breeding with wild boars and created domestication islands in the genome. The same process may also apply to other domesticated animals. In 2019, a study showed that the pig had arrived in Europe from the Near East 8,500 years ago. Over the next 3,000 years they then mixed with the European wild boar until their genome showed less than 5% Near Eastern ancestry, yet retained their domesticated features.
Among the animals that the Spanish introduced to the Chiloé Archipelago in the 16th century, pigs were the most successful to adapt. The pigs benefited from abundant shellfish and algae exposed by the large tides of the archipelago. Pigs were brought to southeastern North America from Europe by de Soto and other early Spanish explorers. Escaped pigs became feral and caused a great deal of disruption to Native Americans. Feral pig populations in the southeastern United States have since migrated north and are a growing concern in the Midwest. Considered an invasive species, many state agencies have programs to trap or hunt feral pigs as means of removal. Domestic pigs have become feral in many other parts of the world, such as New Zealand and northern Queensland, and have caused substantial environmental damage. Feral hybrids of the European wild boar with the domestic pig are also very disruptive to both environment and agriculture (among the 100 most damaging animal species), especially in southeastern South America from Uruguay to Brazil’s Mato Grosso do Sul and São Paulo.
With around 1 billion individuals alive at any time, the domesticated pig is one of the most numerous large mammals on the planet.
