A Relationship Written In Their DNA: New Genetic Evidence Reveals The Origins of Smaller Dogs

For the vast majority of us, dogs are more than just those four-legged mammals who reside within our homes and fetch us our slippers when we get home from work in the evening. They are also an integral part of our lives, demanding such things as table scraps and “walkies” from us, and bestowing heaps of unwavering love and loyalty onto us in return. It only makes sense, therefore, that their irresistible charm and adorable antics can be traced back to a skilled combination of careful breeding and clever genetic manipulation thousands of years ago.

However, according to new research, the modern dog may be less of a result of human intervention and more of a genetic quirk than we may have initially realized. According to an article just published in the January 2022 edition of Current Biology, smaller breeds of dogs might not have arisen from our primitive ancestors’ desire to create a cuddly canine companion to keep them warm at night by their roaring fires. Instead, scientists have discovered that a genetic mutation may be to blame – or rather, thanked – for giving us breeds like the Chihuahua and the Pomeranian.

From Lone Wolf to Domestic Pet

In the realm of biology, it’s no secret that cause and effect play a major role in the advancement of research and the ongoing progression of science. Nearly every branch of science espouses it, with the phrase “correlation does not equal causation” securely tucked away in the back of every researcher’s mind. Nonetheless, in the case of wolves becoming the ubiquitous household dog, this truism still managed to confound some of the most brilliant minds in science. 

The widely held belief that humans had bred larger wolves into smaller and smaller sizes, until they could comfortably fit into their owner’s arms, had prevailed for years. After all, it didn’t take Gregor Mendel with his collection of peas for people to realize that hybridization was the key to coaxing out fairly precise genetic results from two parents. It would only make sense, therefore, that people had fronted the efforts to breed quaint miniature versions of man’s best friend from their more hefty progenitors. 

As it turned out, these smaller dogs were the result of a mutation in their DNA – and, in a novel plot twist that rattled the scientific community to its core, humans were drawn to these diminutive offspring and promptly proceeded to domesticate them. Indeed, it wasn’t so much that pint-sized dogs arose from a desire to have more petite animals watching over human clans. Rather, it was the appeal of these smaller dogs themselves that led to them being adopted by their two-legged – and much less hirsute – pack leaders.

The Role of IGF-1 in Perpetual Neoteny

For the team of scientists at the National Institutes of Health (NIH), trying to find the particular mutation which led to their revelation was the result of a collaborative effort that had spanned over a decade. It took one Jocelyn Plassais, a postdoc who was part of the team of researchers laboring in the genetics lab, to make the suggestion which eventually led to the discovery. She had suggested searching for backward-positioned sequences around a particular gene found in the ancient DNA of canids.

It was following her recommendation that the researchers found an inverted form of a particular gene for insulin-like growth factor 1 (IGF-1) on the genetic strands of a 54,000-year-old Siberian wolf. IGF-1, also known as somatomedin C, is a particular hormone known for encouraging growth in children and promoting anabolic changes in adults. When a reverse form of this hormone is present, it can have the opposite effect on the entity in which it can be found. In the case of these wolves, it led to them being much smaller – and ergo, “cuter” – than expected. 

Genetics: The Past, the Future, and Today

No doubt, the numerous advancements in genetic research throughout the years have led to a myriad of remarkable and life-changing discoveries. However, while specific types of technology – such as single cell sequencing, artificial intelligence (AI), and machine learning – can certainly be applied to more profound applications, it does have other uses. While we all hope to eventually find a cure for cancer or crack the code to eternal life, we should never outright dismiss the more whimsical outcomes of genetic research. 

These discoveries are still valuable, and they do have merit, even if they may not initially seem so at a glance. From both an evolutionary standpoint and a psychological one, virtually all breakthroughs are able to provide us with remarkable insights into modern society and its dynamics with the natural world. And in the case of the humble Canis lupus familiaris, we now know exactly how DNA played a role in fostering the unwavering and mutual devotion shared between humans and their faithful companions.

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