The domestication of the pig (Sus scrofa) is one of the earliest and most widespread achievements in animal husbandry, fundamentally shaping human societies across the Old World. Domestication is a multi-generational process involving the permanent genetic and behavioral modification of a wild species in response to human selection and supervision. This process leads to animals that are less aggressive, more docile, and exhibit physical changes like reduced tooth size, distinguishing them from their wild boar ancestors. As a generalist omnivore, the pig became a valuable resource for meat and fat, adapting well to various human management strategies.
The Primary Centers of Origin
Scientific evidence indicates that the pig was domesticated independently in at least two major geographical centers, leading to genetically distinct lineages. The western origin is centered in the Near East, specifically in or around the Tigris Basin. This domestication event is dated to the early Neolithic period, approximately 8,500 BCE (10,500 years ago).
The second, entirely separate center of domestication occurred in East Asia, primarily in the Yellow River and Lower Yangtze regions of China. Evidence from sites like Jiahu suggests that pig domestication was underway in this area by at least 8,000 BCE (10,000 years ago). This East Asian lineage developed into a genetically unique population, separate from the pigs of the Near East.
Archaeological and Genetic Evidence
Archaeological evidence from ancient settlements reveals morphological changes in skeletal remains that serve as markers for domestication. Primary indicators include a noticeable reduction in overall body size, changes in the skull, and a decrease in the size of the teeth and tusks over generations. Radiocarbon dating of these bone remains helps establish a precise timeline for when these physical changes occurred, confirming the domestication dates.
Genetic evidence traces ancestry through time. Researchers analyze mitochondrial DNA (mtDNA) to trace ancient maternal lineages back to the original wild boar populations. This analysis confirmed distinct genetic signatures for the Near Eastern and East Asian domestic pigs, proving their independent origins. Ancient DNA (aDNA) analysis of pig remains has allowed scientists to compare the genetic makeup of early domestic pigs with modern populations, confirming the spread and mixing of these two distinct lineages.
Global Dispersal and Subsequent Mixing
Following the initial domestication events, both the Near Eastern and East Asian pig lineages began to disperse alongside human migration and trade. The Near Eastern domestic pigs were carried westward into Europe by early Neolithic farmers starting around 8,500 years ago, where they extensively interbred with the local European wild boar populations.
This process of “introgression,” or genetic mixing, was so pervasive that the Near Eastern maternal genetic signal was largely replaced by that of the native European wild boar within a few millennia. Despite this genetic turnover, the pigs retained their domesticated features, resulting in the modern European pig lineage. Meanwhile, the East Asian lineage spread across Southeast Asia, accompanying human voyagers and reaching the Pacific islands.
Later, the East Asian pigs were introduced to the Western world, where they were selectively bred with the European pigs. This mixing introduced desirable traits like earlier maturity and increased litter size into the European stock, creating the genetic foundation of many modern commercial pig breeds globally.