Domesticated pigs got their stripes and spots and other distinctive markings thanks to deliberate breeding efforts by the earliest farmers over the course of thousands of years, according to a new study of pig genetics. While there's no clear evidence of what motivated those early farmers to change their pigs' coats, study coauthor Greger Larson says a number of possible reasons present themselves.
"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." But another possibility, Larson said, "is that the early farmers were as amused and as taken with biological novelty and diversity as we are today" [HealthDay News].
Novelty may have been the desired characteristic in the first agricultural settlements, but in the wild opposite forces were at work to produce pigs with a consistent brown-black color that served as camouflage.
"Every time a gene mutation arose in the wild causing coat colour to change, it was eliminated immediately," says Greger Larson.... "So if a black piglet showed up, that was the one picked off by a predator" [New Scientist].
In the study, which was published in the journal PLoS Genetics, the researchers looked at the DNA sequences of both domesticated and wild pigs, and focused on changes to the melanocortin-1 receptor (MC1R) gene, one of the genes that controls coat color in animals. They found plenty of mutations in both types of pigs, but none of the mutations in the wild pigs had affected the MC1R gene, and therefore hadn't affected coat color. But in
the case of domestic pigs, nearly all the observed mutations altered MC1R. Sometimes there were three layered mutations, indicating that the initial changes had been in existence for a long time. This was evidence that the mutations and resulting coat colour changes were actively encouraged and perpetuated by farmers over thousands of years [Press Association].
Larson says it's entirely possible that the first farmers in the Fertile Crescent were just amusing themselves:
"The Mesopotamians had different-coloured farm animals 5,000 years ago and, in that regard, they were no different to Paris Hilton, who has a pink Chihuahua, or anyone else with animals with unusual coat colours. This study demonstrates that the human penchant for novelty stretches back thousands of years" [Telegraph].
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Image: flickr / redjar