Digging is often a symptom of boredom-too much time spent in the yard alone. Make sure your dog is getting enough exercise and interaction.

Dogs, any dog lover will tell you, are essential. Without dogs we humans are, as a species, poorer, stymied, incomplete somehow. Many of us cannot imagine modern life without dogs, and if pushed, even hardened dog detractors can usually be made to concede the usefulness of dogs in everything from search & rescue work to livestock herding. Now, however, it seems the significance of dogs to humankind is no longer merely a notion shared by dog fanciers. Recently, an anthropologist presented a compelling case that a possible reason humans won out over Neanderthals in the evolutionary battle for survival was our close relationship with dogs.

The context is one of archaeology's biggest mysteries: why early humans came to dominate and Neanderthals died out. Neanderthals had a lot going for them and shared many traits with early humans. They, too, made advanced tools, had a language, and lived in complex social groups. There are many hypotheses about human ascendancy, and a brand new one, based on analysis of excavation finds and cave art, speculates that we owe it to our domestication of and collaboration with dogs. Dogs, the theory goes, made humans vastly better hunters. They helped us identify and catch prey, and they saved us precious energy by transporting animal carcasses, post-hunt, strapped to their backs. (Paleolithic dogs were big and strong, weighing 70 lbs. and upwards.)

Another component of the theory builds on the "cooperative eye hypothesis," the notion that humans may have evolved the highly visible white parts of our eyes-a distinct disadvantage when hunting-specifically to facilitate better communication with each other. Meaning we can "speak silently" to each other using glances and expressions, and we are the only primates to do so. The only other species with an affinity for eye contact and the ability to follow someone else's gaze? That's right. Dogs. Potentially, we even developed this trait in conjunction with dogs-we shaped one another. Humans may have been dogs' ticket to survival and evolutionary triumph (there are 400 million dogs in the world today, and counting). Wouldn't it be great if they turned out to be ours, too?

Here is another sport, like herding and mushing, designed to give dogs an outlet for their innate abilities. Lure coursing mimics a small-prey hunt, something that gets the blood pumping and the paws flying in sighthounds such as Borzoi, Whippets, Greyhounds, Afghans, Basenjis, etc.-and in many other dogs, from Retrievers to Yorkshire Terriers. Dogs chase an artificial lure across a field in a pattern meant to simulate the pursuit of small game. The course is typically between 600 and 1,000 yards long and may include jumps.

Competitions run by the American Kennel Club and American Sighthound Field Association are open only to sighthounds, but AKC's Coursing Ability Test is open to all breeds and many local organizations and clubs offer all-breed lure coursing classes and trials. Where dogs in the sighthound group often require little to no training, other dogs may need practice to get the hang of the game. Not all dogs find it palatable to run as fast as possible away from their human. But chasing down prey is in all canine DNA and many quickly learn to love this fast-paced sport.

Interested in lure coursing with your dog? Google the term plus your locale-or, if you have a sighthound, check out the breed association's website for info on trials near you.