This little piggie had a rather nice outfit

New evidence has been uncovered which may explain the origin of the hugely variable coat colours found in domesticated animals. The research from Durham University has shown human preference to be the cause of the varying colours and not, as was thought before, random mutations.

The study, co-authored by Dr Greger Larson of the Department of Archaeology, compared a gene known as melanocortin receptor 1 (MC1R) in domesticated pigs with their cousins, the Asian and European wild boar. This gene is also present in many other domesticated animals, including cattle, dogs and horses, and is one that has been associated with coat colour previously.

In the wild, natural selection produces boars – the ancestors of our domestic pigs – with black or brown fur. The study found that there was little variation in the MC1R gene in wild boars, as they are already ideally camouflaged for its habitat of dark woodlands.

Go to any farm, however, and you will see anything from the gingery red coat of the Tamworth to the distinctive black and white pattern of the Saddleback. Unlike wild boars, domesticated pigs do not need to be camouflaged, protected as they are from predators by their human owners. With domestication, humans are now responsible for which pigs survive and which go on to reproduce.

The study suggests that it was human choice that selected those individuals with new coat colours for various reasons. Dr Larson says “Early farmers may have decided to change the coat of their livestock for a number of reasons.

One is that it facilitated animal husbandry since it is easier to keep track of livestock that are not camouflaged. Another could be that it has acted as a metaphor for the improved characteristics of the early forms of livestock compared with their wild ancestors.”

Mutations occur spontaneously in the MC1R gene from time to time. In the wild form, most mutations will be removed from the gene pool, as they will most likely change the perfect camouflage causing those individuals to be more easily spotted by predators.

Under human protection, however, these genes can survive. The study shows that this is indeed the case, with some breeds having three separate mutations, occurring at different times.