We often hear about dogs that are dominant, for many of us this conjures up images of an aggressive dog that uses intimidation to get what it wants. In a wild pack of wolves this type of behaviour can sometimes occur, it's essential that law and order are kept for the survival of the pack, and this means strict hierarchy must be kept, but it's far from reality when it comes to the canines we share our homes with today.
Most scientists accept that dogs evolved from wolves or they had a common ancestor. However dogs are not wolves. They are different anatomically, physiologically and socially. The biggest difference between wolves and dogs is their ecological niche. Wolves, as a rule avoid humans whereas dogs have evolved to live near humans.
A common misunderstanding about the concept of dominance comes from the pack theory. The pack theory in the dog world is based on a large part of research collected from studies performed on a pack of unrelated, captive wolves in the 1970s. The results of these early studies suggested that there was a rigid hierarchy in which 'alphas' (leaders) had priority access to resources, forcefully maintaining the group structure through displays of aggression to others.
Because dogs were believed to have descended from wolves, it was then assumed that similar social groupings and violent 'pack' dynamics must therefore exist among domestic dogs as well. What is more, the formation of these dog packs was supposedly based on the desire or drive of certain dogs to be the alpha or top dog of the group, and the resulting hierarchy was based on competitive success.
This theory became so popular that despite the obvious (and very important) fact that dogs and wolves are separated by thousands of years of evolution and that dogs and humans are completely different species, the concept was attributed to explain not only the social interactions between dogs, but also between people and dogs and how dogs should be trained. But dogs are not wolves, and even if they were, the very scientists who performed them and drew their original conclusions have since renounced those captive wolf studies.
Although social hierarchies do exist among dogs, with certain dogs being more controlling than others, studies have shown that such dynamics are not fixed; rather, they are constantly changing. Behaviours that are believed to be dominant behaviours toward people are generally dogs that are being opportunist who are not being guided correctly by their handler.