When man was young on the Earth, millions of wolves roamed world wide. Today, due to centuries of hunting for sport, be it legal or illegal, there are little more than 300,000 wolves left in the world. Wolves are the largest of the canine breed and are often used as the spook in many scary tales.
While wolves would pick off a human or two in times of hunger, but they really got their taste for blood in the Middle Ages when the black plague ravaged Europe. With the bodies piling up faster than the healthy could burn and bury, the wolves began to feast on the dead that had been left out.
This happened several times throughout history during outbreaks, such as smallpox, and during world wars where enemy sides occasionally had to team up to fight starving wolves lured to the bloody battlefields. This taste of human flesh could explain why European wolves are so much more aggressive to humans than their North American brothers.
The black wolves are not a mutation or a natural occurrence within wolves. Black wolves actually stem from interbreeding with dogs. The black fur gene is dominant and passed down through the generations.
You may think white wolves are a similar story, however white fur is genetic to arctic wolves who are some of the toughest wolves on the planet due to their terrain. The white fur is thicker to keep them warm and white to camouflage them in the snow.
Above I mentioned the relationship between wolves and dogs, how they interbred to create the fiercesome black wolf. Wolves and dogs mating is not a very common occurrence, in fact wolves usually see dogs as a food source.
After World War 2, stray dogs ran rampant in Russia which put them on the food chain for Russian wolves. A singular wolf would usually lure a dog to a secluded place where the rest of the pack would pounce.
Even large breeds of dogs are unable to stand a chance against a wolf, much less a pack of them.
Wolves, unlike bears and many other predators, lack the tools to bring down large prey even in packs. Wolves prefer animals like deer or moose and usually swarm them as a pack taking bites from their haunches and underbelly until the animal gets tired. While wolves are large and can weigh upwards of 200 pounds, but even a whole pack can not tackle a 600 pound moose.
When the animal falls from having chunks taken out of it, the pack will feast on the animal while it is alive and kicking.
Most animals that contract rabies go through phases of lethargy and disorientation before they reach the rage phase that marks a rabid animal. However, wolves fly almost immediately into a rage, making them extremely dangerous.
Though wolves are not frequent carriers of rabies, they can contract it from the smaller carriers they eat, like raccoons. Rabid wolf attacks on humans have near dropped off the Earth, but they do still occasionally happen. Rabid wolves are most likely to attack a human in the neck or the head, because of this the rabies usually spread to the human brain too quick to be treated.