Ancient Pig Teeth Reveal Roots of Domestication

New Analysis Links Early Pigs to Human Settlements in South China

A groundbreaking study of ancient pig teeth is rewriting the story of domestication, suggesting that the first steps toward taming pigs involved scavenging for human scraps and tolerating close proximity to early farming communities in South China.

Evidence from the Yangtze River Region

Archaeologists examined dental calculus – hardened plaque – from 32 pig specimens unearthed at Jingtoushan (8,300 to 7,800 years ago) and Kuahuqiao (8,200 to 7,000 years ago), two Neolithic sites in the Lower Yangtze River region. The analysis revealed evidence that these pigs consumed human-associated foods, including cooked starches like rice and yams, as well as an unidentified tuber, acorns, and wild grasses.

The team, led by **Jiajing Wang** of Dartmouth College, identified 240 starch granules within the dental calculus. “These are plants that were present in the environment at that time and were found in human settlements,” explained **Dr. Wang**. The presence of these foods indicates the pigs were likely obtaining them from humans, either through direct feeding or by scavenging.

Parasites Point to Close Proximity

Perhaps even more telling, researchers discovered eggs of the human whipworm (Trichuris trichiura) in 16 of the teeth. This parasite is spread through fecal contamination, suggesting the pigs were consuming human waste or drinking contaminated water. “Pigs are known for their habit of eating human waste, so that is additional evidence that these pigs were probably living with humans or having a very close relationship with them,” said **Dr. Wang**.

Globally, zoonotic diseases – those that jump from animals to humans – account for approximately 60% of all known infectious diseases, according to the World Health Organization (2024). This research highlights how early interactions between humans and animals could have facilitated the transmission of parasites.

A Commensal Pathway to Domestication

Traditionally, animal domestication has been viewed as an active process, with humans intentionally selecting and breeding desirable traits. However, this study suggests a “commensal pathway” was at play with pigs. Wild boars, naturally attracted to human settlements for the readily available food waste, began to tolerate human presence.

This initial attraction led to behavioral changes, such as reduced aggression and increased tolerance, which ultimately favored animals willing to live alongside humans. “Our study shows that some wild boars took the first step towards domestication by scavenging human waste,” **Dr. Wang** concluded.

Beyond Size: A New Approach to Understanding Domestication

Previous research often relied on skeletal analysis to track domestication, focusing on changes in body size. However, **Dr. Wang** and colleagues argue that behavioral shifts likely preceded physical changes. “What probably came first were behavioral changes, like becoming less aggressive and more tolerant of humans,” she stated.

The statistical analysis of the pig teeth also revealed that some specimens possessed smaller teeth, similar to those found in modern domestic pigs in China, indicating the early stages of morphological change. The findings were published in the Proceedings of the National Academy of Sciences.

This research provides valuable insights into the complex process of animal domestication and the interconnectedness of human and animal health in early agricultural societies.