Black-spotted pigs described by Andersson and his research team whose coat colours are the product of human selection.

Thousands of years ago my great relatives were coloured with coats of solid ebony, chocolate browns, and buttery beiges – sensible looking wild dogs unbound by the spots and stripes that have emerged so fashionable today. I look down at my own pristine white coat – flecked, spoiled, and sullied with black ugly specks – and cannot help but sigh at the markings of human intervention.

Alas, I fear my complaints would fall upon deaf ears – being a dog humans have trouble understanding me.

For years I’ve been listening to my owners, both molecular biologists by trade, rant about lab mice and rare species over dinner. Tonight’s table talk really made my ears perk up.

The science unleashed

Researchers at Uppsala and Durham Universities have published findings in the open-access journal PLoS Genetics, which states that humans are actively changing the coat colouring of domestic animals by weeding out and isolating rare mutations.

“I’ve been fascinated to use domestic animals as a model for evolutionary biology,” says Leif Andersson, co-author of the paper and professor at the department of medical biochemistry and microbiology at Uppsala University. “Before culture there was no domestication, so to understand the history of this, provides a history of humanity.”

Well, I’m glad he’s excited about a study that has single-handedly exposed to canines the harsh reality that owners everywhere are judging their pet by its coat– and that the loyalty of dog’s best friend is shockingly superficial.

Basically, the scientists traced a coat colour-controlling gene, melanocortin-1 receptor (MC1R), in both wild boars and domestic pigs from Asia and Europe.

By studying the alterations of this gene in both pig types Andersson and his team were able to explain for the first time in history why there are such differences in the coat colourings of animals in captivity, and those same breeds in the wild.

The research was funded by European and Swedish partners as well as the European Molecular Biology Organization.

The team studied the effects of mutations in MC1R on the pigs’ DNA. While some mutations have little effect on animals, others cause strange patterns in coat colourings – thus producing patchy Chinese Crested miniatures, and two-toned piglets.

So why are these mutations surviving under human supervision and disappearing from the wild? Researchers say that any mutations occurring under Mother Nature’s watch are eliminated by predators. The ability of animals with exotic coat combinations to camouflage is hindered.

You can teach an old theory new tricks

The research teams’ results are significant in that they blow some older theories out of the water.

One theory states that wild coat colouring was lost in domestic animals because it was no longer necessary for animals to protect themselves through camouflage.

Another behavioural-based theory states certain colour genes were analogous with behaviour and when one was weeded out, the other went with it.

“But we can see that this change in these animals has been far too fast for these explanations,” says Andersson. “They might be a by-product, but in this case we are studying a gene that shows that there was a purpose in changing the colour of domestic animals.”

Okay – so it’s clear that early farmers had great reasons to alter their livestock’s coat colours – it rendered their animals more identifiable next to their wild kin, and made it difficult for them to hide in the fields.

But why change the colours of us household dogs and cats?

“There’s evidence that we just like colour for the sake of colour. It’s entirely aesthetic,” says bioarcheologist Greger Larson, co-author of the paper. “Historically it was for practical purposes to distinguish your dog from a wolf, but in modern times it’s to make the dog special.”

People are becoming just as picky about what colour their poodle comes in as they are their own wardrobe. “Some breeders prefer black spots and others white,” says Andersson. “Some want solid, some want them spotted.”

All this talk of mutation isolation and genetic selection can give a dog a complex. Should I be preparing myself for a litter of puppies with spots the same shade as the new curtains?

Front page courtesy of Durham University