"God created man; man created dogs."

That's according to Stanley Coren, professor of psychology at the University of British Columbia and best-selling author of 'The Intelligence of Dogs and Why We Love the Dogs We Do'. It's an opinion formed after years of training and researching dogs for his books - and discovering how precise dog-breeding can be.

"It looks as though by building breeds we did exactly what we set out to do in terms of breeding intelligence and temperament," Coren explains. "We could build an Einsteinian dog through breeding - or one so dumb it could run for Parliament."

Coren came to this conclusion after asking every dog obedience judge in North America to fill out a complete rating for each dog breed, listing the top ten and bottom ten breeds in terms of trainability. Of the 199 judges who responded, there was an amazing similarity in terms of ratings.

"One hundred and ninety listed the Border Collie in the Top 10," Coren says. "One hundred and twenty-one listed Afghan Hounds in the Bottom 10."

Why have we been so successful in producing dogs with the certain characteristics - or lack thereof? Part of the answer may lie in the origin of the modern-day dog - and the amazingly lengthy history of domestication.

Coren's research shows the origins of the domestic dog (canis familiaris) begin when Miacis, the 40-million-year-old arboreal ancestor of both dogs and cats, came on the scene. Cynodictis, the earliest dog ancestor, began running around on the ground 12 million years ago . From Cynodictis evolved Tomarctus, the common ancestor of all canids, including wolves, jackals, foxes and wild dogs, and eventually, the domestic dog.

When and how did the domestic dog appear? Fossil evidence suggests it was between 10 and 15 thousand years ago - and the genetic diversity of dogs suggests that it was not one single event. Different groups of pre-historic humans may have captured different types of wolf or other canid pups and raised them to help them hunt. Selective breeding led to different breeds within a few generations. Then commerce and travel led to these breeds mingling - both with other domestic breeds and possibly the non-domesticated canids in the region.

The result: dogs today have amazing genetic diversity as well as extreme phenotypic diversity [difference in physical appearance controlled by genes] between breeds. (Think Chihuahua vs. Great Dane.) Yet, amazingly, they can still all breed with each other -- and with other canids like wolves, jackals and coyotes.

Amazingly, too, dog-breeding has led to animals perfectly suited to their original purposes. Rottweilers and German Shepherds are alert and bark a lot, making them excellent watchdogs. Pointers silently lead their masters to hiding game and freeze in a pointing stance. Retrievers like water - all the better to jump in and bring back fallen birds for their hunting masters. Hounds hunt down unwanted animals, either by being fast enough to run them down (Afghans and Irish Wolfhounds), or by tracking them with a finely tuned sense of smell (Beagles and Bloodhounds.) Terriers, meanwhile, are brave enough to chase rodents into holes, and have a wiry coat to protect against their victims' bites.

The warm-coated Samoyeds and Siberian Huskies were bred to haul sleds, while Newfoundlands and Saint Bernards are big and strong for hauling loads. Border Collies and Corgis have the wolves' instinct for keeping potential prey animals together (Corgis were purposely bred short to nip at the cattle's legs while avoiding being kicked.) Pomeranians and Maltese were bred to be friendly companions.

Looking at these different breeds, one can see that we humans have, indeed, developed the "perfect" dogs for each task. "In dogs, you can look at genetic differences better than in any other species," Coren says.

That's a sentiment shared by researchers at the University of California, Berkeley and the University of Oregon who are working on the Dog Genome Project, led by Berkeley genetic professor Jasper Rine. Like its human counterpart, the project's purpose is to make a map of all dog chromosomes. The scientists hope to discover the genetic basis of mammalian development and behaviour.

The reason dogs are being studied, as opposed to other animals, is that dog breeds differ, physically and behaviourally, to an extent usually seen only between different species. Therefore, by cross-breeding pure-breed dogs, scientists can discover the genes responsible for those differences. For example, if a Great Dane and a three-kilogram Pomeranian are cross-bred, they could produce offspring that grow very large. A comparison of the genes of the parents and the offspring should show which gene was responsible for size. (For more on the Dog Genome Project, which cross-bred Newfoundland dogs and Border Collies, click here.)

These blatant genetic differences may serve as an amazing laboratory for researchers - but they may be a headache for owners. Breeding the perfect dog for each task, means that, from birth, your Border Collie will have the urge to herd your sheep - but if you have no sheep, it may find that herding your young children will do just nicely. (Nice for the dog - not so nice for the children.)

"After weeks of obedience training, a Boxer may have only learned to heel, while a poodle [which judges rated in the Top Ten in ability to learn obedience] can do much more," Coren says. "You must then make the owner understand it's the nature of the breed, not the fault of the individual."