The theory of neoteny was reinforced by the famous Russian silver fox experiments done at the Institute of Cytology and Genetics in Novosibirsk, Siberia under the direction of geneticist Dmitry K. Belyaev.

Belyaev was asked by some Russian fur traders if he could create a tame silver fox that wouldn't bite or be afraid of being handled by humans.

He succeeded. But within a few generations, the foxes began to show other neotenous traits, wagging tails, barking. And while they exhibited no fear of humans, their coats became variegated and mottled, which decreased the value of their fur to "nulyu" (Russian for zero).

In 2002 Raymond and Lorna Coppinger presented a new model for domestication, based partly on Belyaev's work, and partly on observations of modern wolves, some of whom scavenge at human garbage dumps. Their model stated that wolves (or early dogs), were attracted to the garbage at our ancestors' encampments. And the animals who were the boldest, i.e., most unafraid of our human ancestors, and had the least tendency to bite, were slowly welcomed into our human packs. Over time, these bold, non-biting proto-doggies, became our closest companions.

However, since the trait of "dominance" has been equated with being able to control resources, and since the boldest proto-dogs would've had more control over who, within in their specific family groups, were able to gain access to the human garbage, there are still two unanswered questions. How does selecting for dominance/boldness translate into the opposite, and supposedly neotenous, trait of submission? And if our ancestors were breeding for the neotenous quality of submissiveness, why do so many dogs still exhibit dominant tendencies?

There may be another problem. While the Coppingers' "dogs-as-scavengers" theory, and Belayaev's work with foxes are important steps in our current understanding of canine evolution, they're still based in large part on the idea that diversity in dogs is solely (or primarily) the result of human intervention, having little to do with some inherent quality found in the dog/wolf/(fox) gene pool.

New genetic research may change that. Evolutionary biologist Ursula Goodenough wrote about this research recently for NPR. "Breeding programs," she writes, "can only yield as much variation as is harbored in the gene pool, and the dog gene pool [is] a gold mine."

So what's inside this gold mine?

Two things: insertional mutations, and tandem-repeat sequences.

Goodenough: "Dog genomes harbor DNA sequences, called mobile SINEC_Cf elements, that tend to leave one chromosomal location and insert themselves into a second ... Should they happen to insert into a gene or a regulatory element, this modifies the encoded genetic information, generating ‘insertional mutations.' It's been estimated that dog genomes have at least 11,000 potentially mobile SINE elements whereas human genomes have less than 1,000."

The second source of Fido's diversity comes during fetal development. That's because dog DNA also carries a feature called "tandem-repeat sequences," where one bit of genetic code is repeated over and over (and over and over). "When such regions are copied in the germ line," Goodenough says, "the copying enzymes tend to ... synthesize too many or too few repeats, generating ‘slippage mutations' in eggs and sperm that are inherited by offspring. The slippage rate [is] far higher in dogs than in other carnivores."

The next question is, at what point did the insertional mutations and slippage rates in the dog's DNA come into play? Was it during the domestication process, or were they already there, lying in wait somewhere inside the wolf's DNA?

We know that all wolves exhibit the same basic morphology, species-wide, with only fairly minor variations in size, color, coat density, etc. So on first glance it seems very unlikely that they would possess the genetic blueprint necessary for all the variations we see in domesticated dogs. Yet it turns out that the DNA of modern wolves also shows the same high levels of the two mutational factors. So apparently, dogs did, in fact, inherit their diversity and variability directly from wolves.

What does this have to do with a unified dog theory?

For the past six or seven years, key figures in the positive training movement have been dismissing or denigrating the dog's genetic history. Dr. Ian Dunbar, a key figurehead in the movement has said, "Learning from wolves to interact with pet dogs makes about as much sense as, 'I want to improve my parenting -- let's see how the chimps do it!'" (This is based on a comparative DNA analysis between dogs and wolves in relation to roughly the same percentage of DNA shared by humans and chimps.)

While this idea makes sense on a certain level, there's such a huge divide between humans and our closest genetic relatives, that there's really no comparison to dogs and wolves. It's true that chimps are much smarter than we previously thought, but they still don't design and construct buildings, they don't play guitar, write poetry, build airplanes, hold elections, take summer vacations, shop for shoes, etc.

So yes, there are differences between dogs and wolves, but it's not as big a divide as the one that exists between humans and chimps. And the key differences exist primarily because of the dog's relationship with humans, a relationship that for thousands of years was based, not on the dog's talent for scavenging, but on how our ancestors used the dog's hunting instincts, which were directly inherited from the wolf.

So while the Coppinger model of domestication may be valid, at least in part, and while neoteny is surely a factor in terms of how dogs fit in to a human household, neither model can successfully explain how dogs-as-scavengers ended up being herders, pointers, ratters, sighthounds, scenthounds, retrievers, and on and on.

Other questions remain. For instance, do foxes have these same mutational qualities in their DNA? If so, are they found in the same levels as in dogs and wolves? (My hunch is that foxes have them, just at lower levels). After all, foxes are the only canid who don't hunt large prey by forming packs[1]. And the only way the pack style of hunting can be successful is through variability in temperament, relative to each animal's role in the hunt: some need to be bold while others need to hold back, or circle the prey, etc. That's why in every pack, some wolves have a direct (or dominant) temperament, while others are more indirect (or submissive). If they all had the same approach to prey, the hunt would surely fail.

This diversity of temperament can also be seen in every litter of puppies, from great Danes to Chihuahuas, a clear spectrum from the most direct (or "dominant") to the most indirect (or "submissive"). And with all the different kinds of breeding programs humans have devised over the last 14,000+ years, why does this diversity - this spectrum from dominant to submissive - still show itself with such clarity and exactitude in each and every litter of puppies born to every female dog, in every breed imaginable?