These days many pet parents are accused of treating their pets – canine, feline, and otherwise – as though they were human children: dressing them up, buying lots of special toys and accessories, spending lots of money on food and grooming, and even arranging ‘play dates’ with their other pet parent friends.
But perhaps the link between humans and dogs is much closer than we originally imagined. Scientists involved in mapping the canine genome project have discovered that skull development in humans and dogs is very similar, and that learning how different dog breeds have come to have different types of skull shapes may one day help us understand human cranio-facial development and deformities.
It’s been eight years since the dog genome was mapped, and in an article titled, “The Genetics of Canine Skull Shape Variation”, in the February 2013 issue of Genetics, researchers at the National Human Genome Research Institute and the National Institutes of Health review the progress made in defining the genes and pathways that determine dog skull shape and development.
The research implications extend far beyond the interests of dog fanciers and breeders. “Dogs can serve as a model for skull growth and shape determination because the genetic conservation between dogs and humans makes it highly likely that cranio-facial development is regulated similarly between both species,” says co-author Dr. Jeffrey Schoenebeck.
The discoveries are important for human health and biology, especially for children born with cranio-facial deformities, where skull bones fuse prematurely causing facial malformations, such as wide-set bulging eyes and broad foreheads, resulting in dental, eye and other physical problems.
From Pug to Saluki – unique skull shapes
Skull shape is very complex and involves multiple genes and their interactions. Due to standardized breeding practices for dogs, more than 400 breeds have been documented worldwide, and since each breed has distinct physical features, researchers can review traits such as skull shape. For example, scientists are beginning to identify which genes cause a Bulldog or a Pug to have short pushed-in faces, and those that cause Saluki’s or collies to have narrow, elongated snouts.
Between these two distinct canine cranium shapes are many variations that are also breed-specific – but can’t be as neatly categorized – such as the rounded skull of the Chihuahua or the downward pointing snout of the Bull terrier. Researchers now use genome-wide association studies to identify areas of interest that could be associated with these kinds of subtle differences.
The use of genome-wide association studies in determining genetic variation in dogs is still new. What’s exciting says Dr. Schoenebeck is that, “we may find new roles for genes, never before implicated in cranium development” and because similar genes and genetic pathways operate in humans, defects in cranio-facial developmental may become better understood.
Identifying the causative genetic mechanisms of these variations in dogs offer researchers who study human cranial abnormalities “a way to figure out what sort of genetic variation matters and what doesn’t”, says co-author Dr. Elaine Ostrander.
Scientists believe there’s still a lot more research to do on cranio-facial development, and it’s also clear that the connection between us and our furry friends is in our heads as well as our hearts.
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