Dog Fur Evolution

Dog hair seems to be about as diverse as something can get: it comes in many colors, lengths, thicknesses, and degrees of curliness. Researchers at the (U.S.) National Human Genome Research Institute wondered what the genetic basis was for some of those these differences.

The scientists began by keeping things simple: they looked for genetic variation in the genome of just one breed of dog, the dachshund, which comes in short-haired, long-haired, and wiry-haired varieties. After looking at some 50,000 “spots” (pardon the pun) in the genetic codes of 100 dachshunds, the researchers discovered that differences in one location on canine chromosome 13 determine the wiriness of dachshund hair; a particular gene known as R-spondin-2 encodes a protein that results in the wiry hair follicles and produces the characteristic “mustaches” of some dog breeds. Meanwhile, a mutation in a gene called FGF5 correlated with longer hair; 91 percent of the long-haired dogs in the study had the mutation, compared to only 4 percent of the short-haired dogs.

The incredible diversity of dog fur is largely due to differences in just three genes.

In a corresponding study, the researchers examined the genes of 76 Portuguese water dogs to pin down the genetic cause of curly hair. They learned that a difference in the gene for hair protein keratin caused the curliness.

Knowing that differences in those three genes alone resulted in differences in hair length, wiriness, and curliness, the researchers embarked on a bigger project: they analyzed the genomes of dogs from 80 breeds (nearly 1,000 dogs in total) to learn how the identified genetic changes interacted to result in the varieties of dog hair. They discovered that different combinations of the gene types result in the seven coat types most common among the dogs sampled.

For example, basset hounds have none of the three mutations, and instead have short, straight-haired coats. Dogs with all three mutations have long, curly hair and mustaches, such as the bichon frisé. (For this very reason, AiG’s Ken Ham has fondly referred to his family’s bichon frisé as a “mutant”—see “As I Always Said: ‘It’s a Mutant!’”)

Thus, the incredible diversity of dog fur is largely due to differences in just three genes. Cornell University geneticist Gregory Acland commented, “All the unique characteristics are something that occurred once a long time ago and have been preserved ever since.” That’s due not only to the effects of natural selection (e.g., only long-haired dogs surviving in cold climates), but also due to the power of artificial selection (e.g., breeders selecting for certain traits, resulting in dogs with specific characteristics based on everything from farmers’ needs to pet owners’ fancies).

What does this study tell creationists? It gives us a good idea of the scope of genetic differences required to account for the diversity within one part of what was probably one created canid kind (extending beyond dogs to wolves, dingoes, etc.). We cannot say for sure how many of these differences are the result of a mutation and how many were simply due to the diverse information God gave each created kind; however, we can get a better idea of how the kind may have changed over the four millennia since Noah’s Ark.