Have you heard the story that every domestic dog on the planet is the offspring of grey wolves who found themselves welcomed by warm fires and affection into a human encampment?

Science and Fairy Tales

The idea that wolf cubs and human children became playmates after their parents begin sharing food around a campfire is so widely believed that Bryan Sykes, professor of genetics at the Weatherall Institute of Molecular Medicine at Oxford University and editor of The Human Inheritance: Genes, Language and Evolution, speculates about it in his book, The Seven Daughters of Eve: The Science That Reveals Our Genetic Ancestry. (Sykes 2001:258-9)

Sykes even suggests that wolves liked humans so much that they put up their cubs for adoption by their new human friends. Wolves who preferred humans to their own species eventually become our domestic dogs.

A charming tale, to be sure, but the path to the dog's domestication is much more complicated.

Multiple Paths To Domestication

In 1997 Charles Vili and his colleagues concluded that dogs split off from wolves more than 100,000 years ago. Their paper Multiple and Ancient Origins of the Domestic Dog, published in Science vol. 276, 13 June 1997, supports wolf ancestry for all dogs from multiple crossings:

The archaeological record cannot resolve whether domestic dogs originated from a single wolf population or arose from multiple populations at different times. However, circumstantial evidence suggests that dogs may have diverse origins. During most of the late Pleistocene, humans and wolves coexisted over a wide geographic area, providing ample opportunity for independent domestication events and continued genetic exchange between wolves and dogs. The extreme phenotypic diversity of dogs, even during the early stages of domestication also suggests a varied genetic heritage. Consequently, the genetic diversity of dogs may have been enriched by multiple founding events, possibly followed by occasional interbreeding with wild wolf populations. Science, vol 276, 13 June 1997

But in 2002, research by Peter Savolainen suggested a "common origin from a single gene pool for all dog populations" between 40,000 and 15,000 years ago in East Asia. In Genetic Evidence for an East Asian Origin of Domestic Dogs

According to the 2002 paper:

The origin of the domestic dog from wolves has been established, but the number of founding events, as well as where and when these occurred, is not known. To address these questions, we examined the mitochondrial DNA (mtDNA) sequence variation among 654 domestic dogs representing all major dog populations worldwide. Although our data indicate several maternal origins from wolf, >95% of all sequences belonged to three phylogenetic groups universally represented at similar frequencies, suggesting a common origin from a single gene pool for all dog populations. A larger genetic variation in East Asia than in other regions and the pattern of phylogeographic variation suggest an East Asian origin for the domestic dog, ~15,000 years ago.

There had also been a theory that the modern dog is a descendant of the East African wild dog known as a jackal. This study points instead to a population of grey wolves in modern India as the ancestor of modern dogs.

Verginelli et al. (2005) put both results under the microscope for another reason. He says the dates used need to be reevaluated because poorly calibrated "molecular clocks" have systematically overestimated the age of geologically recent events. (Note: See our Design of Life article "Molecular clock keeps good time - twice a day?" for a discussion of the problems with using "molecular clocks" to try to reconstruct the history of life.)

Did Dogs Domesticate Themselves?

While the DNA research is open to debate, dogs are clearly the first domestic animals to appear in the archaeological record. Archeologists have found evidence of fully domesticated dogs living with humans in Eurasia at least 14,000 years ago. Despite the fact that dogs require a lot of food and care, says UCLA biology professor Robert K. Wayne,

They must have served an important function in ancient societies, and have been thoroughly domesticated to move great distances without wandering off into the countryside. We believe they were a fundamental part of ancient societies. Dogs may have been valued for their hunting skills, security, transport, warmth, perhaps even helping early travelers to move great distances.

Also, because dogs eat meat, they were sharing with humans a food source that was difficult and dangerous to get - unlike, say, goats. So they were an interesting choice for early domestication. (Humans could, of course, eat the dogs in an emergency.)

Susan Crockford Ph.d., a zoologist, specializes in the domestication of dogs. Crockford, believes thyroid hormones played a role in domestication of the dog. In her paper, Crockford  says "dogs appear to have been generated on at least three separate occasions (perhaps more) from geographically distinct ancestral populations of wolf (i.e., different subspecies)."

It turns out humans may not even have domesticated the dog, in the sense that we usually suppose.

Crockford observes, "Scientists understand very little about the precise biological and anthropogenic mechanisms responsible for transforming wild animals into domestic ones."

She adds that much of what we "know" about breed development is based on assumptions about the early dog/human relationship that are probably incorrect. "There is no evidence to suggest that deliberate human actions precipitated domestication in most animals and the present consensus of opinion is that domestication was initiated by the animals themselves," says Crockford.

We do not really know much about how wild animals usually become tame. Most tame animals were born to tame parents and handled by humans from such an early age that they simply accept humans as safe and friendly.

So what happens when you hand raise wild wolf cubs as if they were puppies?

 In fact, Vilmos Csanyi at Lorend Etvos University in Hungary, together with graduate students, did just that recently. Their work, filmed by a colleague, pointed up just how different the dog is from the wolf in its social behaviour around humans:

At five weeks of age, the wolf cubs were introduced to a room containing their hand-raiser and an adult dog, both sitting motionless, and the human staring into space. Mr. Miklusi shows a video of what happened:

A gawky wolf cub stumbles awkwardly up to the dog, sniffs it a bit, then does the same to the human before climbing into the person's lap and going to sleep. No eye contact is made with its caregiver; the cub appears to treat the person like a comfortable piece of furniture.

Mr. Miklusi's next video shows a dog puppy wandering into the same situation. It too wanders over to the dog for a sniff, but then waddles over to its caregiver, stares it in the face and begins yipping for attention.

When the caregiver remains motionless the dog wags its tail, barks, and begins licking the person, trying to establish contact. It then sits down in front of the caregiver, ears up, apparently waiting for contact.

By 2001, experiments had also demonstrated that dogs are also far better than chimpanzees at using social cues provided by humans to find food. As Colin Woodward notes in The Chronicle of Higher Education (April 15, 2005),

Chimpanzees, our closest relatives, have been shown to follow a human’s gaze, but they do very poorly in a classic experiment that requires them to extract clues by watching a person. In that test, a researcher hides food in one of several containers out of sight of the animal. Then the chimp is allowed to choose one container after the experimenter indicates the correct choice by various methods, such as staring, nodding, pointing, tapping, or placing a marker. Only with considerable training do chimps and other primates manage to score above chance. Dogs, however, performed marvelously, and even outdoor dogs with no particular master could solve the problem immediately. (The researchers controlled for the scent of the food.) By 2001 a raft of experiments by Mr. Csányi's team and another led by Michael Tomasello of the Max Planck Institute for Evolutionary Anthropology, in Leipzig, Germany, showed that dogs were far more skilled then either chimps or wolves at using human social cues to find food.

This is a revealing finding, because the human and chimpanzee bodies are quite similar, as are the dog and wolf bodies. Yet the dog jumps a species barrier to interpret human social cues easily, and the other species do not.

Is the dog domesticated? Did it domesticate us?

Many examples of interspecies cooperation can be understood in terms of concepts like Darwin's natural selection - that is, the relationship developed because both species survived better. However, the relationship between human and dog is unusual because of the very high emotional interconnectedness. In such a case, it is risky to assume that survival is the goal that explains everything.

Is Rover designed to be your 'best friend'? It may be a while before we know enough. But one thing we do know: the human/dog relationship is more than utilitarian. It is a love story that captures our imagination, the very stuff of fairy tales.