Evolution has played a major role in the changes from wolves to the domesticated dogs. Dogs have adapted to humans so much since their evolution from wolves. One of the evolutionary changes that occurred to the domesticated dogs is that they have developed very similar enzymes in their digestive tract as humans, due to them eating the same foods as humans which were left over scraps from the dinner table. Dogs are so much more intelligent and receptive than we give them credit for. You must remember, dogs have been companions of humans for 20,000 years and almost all of those years there has been conflicts in practically all societies. As an aggressive enemy approaches humans must have taught their dogs to be quiet. Therefore, It would only be logical that dogs may have adopted the “when to and when not to” bark instincts from being in so many conflicts and wars. Evolution always plays a part in the behavior of any animal.