Pigs, often associated with farm life, are indeed domesticated animals. This means humans have significantly influenced their genetics and behavior over many generations. The concept extends even to feral pigs, which, despite living in the wild, still carry the genetic legacy of their domesticated past.
Understanding Domestication
Domestication is a biological process where humans exert control over the reproduction and care of another species, leading to genetic and behavioral changes that benefit both parties. This sustained, multi-generational relationship results in an organism developing traits that increase its utility to humans. Through controlled breeding, humans select for desirable characteristics, a process known as artificial selection.
This differs from taming, which is merely a behavioral modification in a wild animal, as domestication involves permanent genetic changes passed down through generations. Domesticated animals often exhibit a predisposition toward humans, and their mate choices are influenced by human intervention. While wild animals adapt to their environment through natural selection, domesticated animals evolve under human selection, favoring traits like tameness. This selective pressure over many generations transforms both the physical appearance and behavior of the species.
The Historical Path to Domesticity
The domestication of pigs, originating from the Eurasian wild boar (`Sus scrofa`), began during the Neolithic period, a time when human societies transitioned from hunting and gathering to farming. Archaeological evidence suggests that pigs were first domesticated in at least two independent centers: the Near East (specifically the Tigris Basin) and China. This process started around 9,000 to 10,000 years ago in the Near East, with evidence of pigs in Cyprus dating back over 11,400 years ago, implying earlier domestication on the mainland. A separate domestication event occurred in China approximately 8,000 years ago.
Early humans likely began domesticating pigs for various reasons, including their utility as a food source and their ability to consume waste. The relationship may have started as a commensal one, with wild boars attracted to human settlements for food scraps. Over time, hunter-gatherers transitioned from merely hunting wild boars to actively raising them, selecting individuals with more desirable behaviors and physical traits. When domesticated pigs arrived in Europe from the Near East around 8,500 years ago, they interbred extensively with local European wild boars, leading to a complex genetic history where modern European domestic pigs share less than 5% of their DNA with their original Near Eastern ancestors.
Distinguishing Domestic Pigs from Wild Boars
Domesticated pigs (`Sus domesticus`) differ physically and behaviorally from their wild ancestors, the wild boars (`Sus scrofa`), as a direct result of centuries of selective breeding by humans. Physically, domestic pigs typically have a rounder body shape, shorter legs, and softer skin, contrasting with the leaner, more muscular build and longer, narrower bodies of wild boars. Their coat colors vary widely, including white, pink, or reddish hues, whereas wild boars generally possess a dark, coarse, bristly fur coat, often black, brown, or dark gray.
Another distinguishing feature lies in their dentition; wild boars possess prominent, continuously growing tusks. Domestic pigs, conversely, have significantly smaller canine teeth, and their tusks are often absent or trimmed. The snout of a domestic pig is typically shorter and stubbier, while wild boars have longer, more elongated snouts. Furthermore, domestic pigs often display traits like floppy ears and curlier tails, which are less common in their wild counterparts.
Behaviorally, domestic pigs are generally calmer and more docile due to generations of breeding for tameness, making them easier for humans to manage. Wild boars, however, are more aggressive, territorial, and wary of humans. While both are omnivores, domestic pigs primarily consume human-controlled diets of grains, whereas wild boars are opportunistic foragers, eating a wide variety of plants, roots, nuts, small animals, and carrion. Domestic pigs also have different reproductive patterns, with females capable of breeding more frequently and at a younger age than wild boars.
The Status of Feral Pigs
Feral pigs are domesticated pigs that have escaped or been released into the wild and have subsequently adapted to living without direct human supervision. They retain the genetic markers of their domesticated past, but their physical and behavioral characteristics often begin to shift as they re-adapt to wild environments.
As feral pigs establish themselves in the wild, they can redevelop some traits that resemble their wild boar ancestors. For instance, they may become leaner, grow thicker, coarser hair, and develop more pronounced tusks, although these changes do not make them genetically identical to wild boars. Their behavior also becomes more cautious and secretive, similar to wild animals, as they learn to forage for themselves and avoid humans. Despite these adaptations, feral pigs are distinct from wild boars and can interbreed with them, leading to hybrid populations in some regions.