Domesticated pigs (pictured) routinely interbred with wild boars — contrary to common assumptions that humans kept their animals isolated.

Credit: Bill Ling/Getty

Humans domesticated pigs from wild boars independently in Anatolia (modern-day Turkey) and East Asia around 9,000 years ago. To learn about pig-population histories, a team led by Laurent Frantz at the University of Oxford, UK, analysed the genomes of more than 600 modern pigs and wild boars. After initial domestication in Anatolia, the ancestors of European pigs interbred with at least two different populations of wild boars that ranged between Europe and Anatolia. Pigs from East Asia seem to have interbred with local boars too. Despite this wild mixing, domestic pig genomes show signs of positive selection at regions that include genes involved in behaviour and anatomy.

The researchers propose that ancient herders repeatedly selected pigs with useful traits, counteracting the effects of the wild boar genes.

Nature Genet. http://dx.doi.org/10.1038/ng.3394 (2015)