There is some evidence that Proto-Indo-European society was divided (at least theoretically) into three functions. One of these would have been the martial function, made up of young unmarried men who had a strong totemic identification with the wolf, and more rarely the bear. The PIE peoples did not know writing, so we have to surmise these things from the social structures of the historical societies descended from PIE speakers, along with common attitudes toward and behaviors in the military classes of those societies. (The grandfather of this scholarship was a Frenchman named Georges Dumezil). We don't know for sure that PIE warriors would wear wolf pelts, but we know later cultures did so, while also donning the hide of bears and wearing wolf-masks during certain military ceremonial rites. Here are some examples:

Here is an Attic (early Greek) warrior wearing a wolf pelt displayed on an olive oil vase from 460 BCE. The warrior is shown on all fours under a stylized tree. This could be meant to show the warrior in some sort of magical half-human state, or it could depict the silent approach of a warrior to his enemy, creeping below or behind natural defilade.

Here are two plates found in Öland, Sweden from the Viking era. They depict warriors wearing bear and/or wolf pelts and so are probably showing us the famous 'berserkers'.

[edit]The Sutton Hoo burial hoard unearthed in England and dating from early Anglo-Saxon times contains a purse lid with an image of a man/warrior flanked on either side by wolves very much like the first plate from Öland.See this image. The purse lid has some other type of animal in the center; see full item here.[/edit]

There are some Celtic tribes that used wolf-like masks in their initiation rites, and wolf-warriors play a prominent role in Irish mythology. [edit]This can be difficult for the modern observer to see, but the helmet with face mask also found at Sutton Hoo has stylized eyes meant to evoke the image of a wolf. See this image.[/edit]

A number of writers and scholars have commented on this connection between wolves and warriors in Indo-European societies. I agree with some who feel this ancient association is the root of modern cryptid legends like werewolves and folktales like Little Red Riding Hood, but that's not known for sure.