An Island's Genetic Signature
The Jeju Black Pig (Sus scrofa domesticus) is a distinct lineage native to South Korea's volcanic Jeju Island. Historical records confirm its presence since at least the 1400s, but its origins likely trace back to Manchurian-type pigs introduced 2,000 to 3,000 years ago. Long-term geographic isolation on the island has resulted in unique genetic characteristics compared to mainland Korean pigs. This isolation created a genetic bottleneck, which, combined with natural selection, shaped the pig's genome.
The breed faced near-extinction during the 20th century due to crossbreeding with larger, faster-growing Western breeds like the Berkshire, introduced during the Japanese colonial period (1910-1945). By the 1980s, the purebred population was critically low. In 1986, the Jeju Livestock Promotion Institute launched a restoration project, starting with just five purebred individuals. This conservation effort proved successful, and in March 2015, the Jeju Black Pig was designated a Natural Monument of South Korea (No. 550) to protect its unique genetic heritage. Today, the Jeju Provincial Livestock Institute maintains a carefully managed population of several hundred purebred pigs to ensure their survival.
A Genome Adapted for Superior Meat
The Jeju Black Pig's genome shows the adaptation. Scientific analysis reveals specific genes that contribute to its prized meat quality, which is known for superior marbling and redness. One important genetic variant is found in the myosin gene MYH3. This variant increases the production of MYH3 protein, which promotes the development of "slow-twitch" muscle fibers. These fibers are redder due to higher myoglobin content and store more intramuscular fat, resulting in the meat's characteristic marbling and flavor.
Genomic studies have identified clusters of genes under positive selection related to fatty acid transport and metabolism. These adaptations likely helped the pigs thrive on local forage found on the island's volcanic terrain. The genetic makeup also explains the meat's firm texture and why it rarely suffers from quality issues like "pale, soft, exudative" (PSE) appearance, a common problem in commercial pork. Whole-genome sequencing shows clear selection signatures that differentiate the Jeju Black Pig from Western breeds, showing its long history of local adaptation. RNA sequencing of muscle tissue has identified hundreds of differentially expressed genes between Jeju Black Pigs and Landrace pigs, with candidates like MYH2, MYH6, and IGF1 linked to the unique muscle and growth characteristics.