Pigs force rethink on human history

11 March 2005

The largest ever study into the ancestry of the humble domestic pig has unearthed a new evolutionary theory behind one of our most common farmyard animals.

Scientists from the Henry Wellcome Ancient Biomolecules Centre and the University of Durham have traced DNA from wild boar and domestic pigs revealing five brand new regions of domestication and a fascinating insight into early farming practices.

The study, funded by the Wellcome Trust and the Arts and Humanities Research Board, is published in the 11 March edition of Science [http://www.sciencemag.org/]and reports that, in addition to new centres of domestication, and contrary to popular belief, European domestic pigs derive from wild boar native to Europe and not from wild boar indigenous to the Near East.

By analysing the DNA of nearly 700 pigs, geneticists and archaeologists have found common genetic fingerprints between domestic pigs and wild boar, but these shared fingerprints are found in a wide variety of geographical locations and not just in the Near East.

‘Many archaeologists have assumed the pig was domesticated in no more than two areas of the world, the Near East and the Far East, but our findings turn this theory on its head,’ said Dr Keith Dobney, from the department of archaeology at the University of Durham. ‘Our study shows that domestication also occurred independently in central Europe, Italy, Northern India, South East Asia and maybe even Island South East Asia. The spread of farming into these areas during the Neolithic seems to have kick-started local independent domestication of wild boar.’

Greger Larson, from the Ancient Biomolecules Centre said: ‘Our data show domestication was not as rare as previously thought and that the question now is not “where were pigs domesticated?”, but rather “where were they not domesticated?” This forces us to reconsider our assumptions about early human history and the beginnings of domestication.’

Archaeological evidence suggests the pig was first domesticated 9,000 years ago in Eastern Turkey. Prior to this, wild boar were important prey animals for early hunter-gatherers across Eurasia. Domestication of pigs, and other animals, resulted in a shift away from hunting to farming and signalled the start of the agricultural revolution.

‘Studying domestication provides us with important clues into human history and allows us to study major evolutionary changes over very short time scales,’ said Keith Dobney. ‘Our next step is to study the archaeological remains of pigs from these regions to see whether their morphology, that is their size and shape, and ancient DNA signatures support our current findings. Whatever the results, it is becoming clear that our understanding of early agriculture is more complicated, and more interesting, than we thought.’

The DNA samples came from the jaw bones or teeth of museum specimens and the hair or soft tissue from more recent specimens.

Picture: A modern domestic pig. Credit: Jeremy Walker/Science Photo Library.