By Karin Krisher
The question has long puzzled evolutionary biologists and laymen alike: What makes a dog so trainable? More specifically, what is the difference between dogs and their ancestors, wolves, that determines domesticity?
Scientists have been searching for the veritable Higgs boson of canine genetics since species classification went mainstream. But their efforts could prove futile, if only because they’re looking for something that may not actually exist.
The widely-accepted view of canine evolution posits that the domesticated dogs we know and love evolved directly from the wolves we fear and persecute. It’s clear that dogs and wolves have striking similarities. Dogs are, in fact, classified as a subspecies of Canis lupus (the wolf). But does this type of evolution necessarily indicate one genetic variation that can account for all domestic behavior? Or is domesticity something else entirely, an evolutionary outcome whose genetic source can’t be directly identified, much like the human condition?
Several evolutionary theorists believe that this is the case—the so-called gene of domesticity isn’t a gene at all, but a compilation of behavioral evolutionary mechanisms. Taking this theory further, domesticity isn’t a product of a singular genetic difference, but itself. In short, domesticity is a product of domesticity.
Notes James Serpell in The Domestic Dog: Evolution, Behaviour and Interactions with People: “The tremendous success of the domestic dog is based on its ability to get people to raise its pups….The evolution of the dog is probably identical to other domestic species that first began as village scavengers, became useful as food and fiber, and then, as they became tameable and trainable, were used for work.”
More evidence for the idea that trainability in dogs is a long-term result of training itself (and human proximity) exists buried in the very experiment that was designed to call out the “domesticity gene.” When Russian scientist Dmitri Belyaev set out to breed a tameable fox, searching for the gene that defines the domesticated dog, he found unexpected results.
Selecting only for a behavior, tameness, as he bred from a pool of more than 10,000 foxes, Belyaev discovered that other, unselected traits emerged—namely droopy ears and a “peculiar tail position” characteristic of the common domesticated dog. It is notable, too, that these traits do not exist in wolves, and would have been very difficult for Neolithic breeders to create. These emergences indicate that “what seems to be a selection for a single gene produces large morphological and behavioral effects.”
It would be difficult to convince anyone that trainable dogs are not evolved from wolf ancestors; they are. However, the main difference between the two is not to be found in a single genetic marker. Just as human disposition cannot be allocated to a single gene, neither can the domestic disposition be allocated to one canine gene, or even a few. Trainability and tameness are more than this, and at the same time less—they are but two observable traits of the domestic dog that can simultaneously affect and be affected by all other genetic selections.
In this light, the puzzle of the tameness gene seems much less puzzling. In fact, in this light, it may disappear altogether.