Today's pigs in China have a pedigree dating back at least 8,000 years to some of the first domesticated swine, scientists say. The finding provides a more detailed picture about the history of animal husbandry and shows that pigs may have been tamed in places archaeologists had never before guessed. The study is part of an effort to chart the movement of domesticated pigs by comparing DNA samples from the animals across the globe. Tracking the swine could shed light on human migration over the last several millenniums, researchers said.
     Researchers compared 18 samples of DNA extracted from ancient swine bones collected along China's Yellow River to more than 1,500 modern pig specimens. The scientists analyzed a specific kind of DNA called mitochondrial DNA, which is passed down maternally. They found that the stock of modern-day pigs in Asia matched that of ancient pigs in the same region, demonstrating that the modern animals had ancient roots in the region. The researchers also found that the Asian pigs came from only a few species among today's many existing species of wild boar. What this means for agriculture is that many traits that exist among wild species have not yet been exploited through breeding, said UCLA evolutionary biologist Robert Wayne, who was not involved in the study.
     The researchers also found evidence that pigs had been independently domesticated in isolated pockets of Asia - India, Southeast Asia and Taiwan - that archaeologists had never before noted as part of the pig-taming storyline. The fact that the same pigs have stuck around for a while meant their humans probably did too, Wayne said.
     Tracing the roots of pig domestication may help in tracking past human migrations and cultural development, said study lead author Greger Larson, an evolutionary biologist at the University of Durham in England. "Previous studies of European domestic pigs demonstrated that the first pigs in Europe were imported from the Near East. Those first populations were then completely replaced by pigs descended from European wild boar. However, despite the occurrence of genetically distinct populations of wild boar throughout modern China, these populations have not been incorporated into domestic stocks. The earliest known Chinese domestic pigs have a direct connection with modern Chinese breeds, suggesting a long, unbroken history of pigs and people in this part of East Asia," Larson said.

Sources: Los Angeles Times (19 April 2010), ScienceDaily (20 April 2010)