Well, from what I've researched, the idea that the “free soul” of the shaman can take an animal form (in this world or the spirit world) is quite common-place. It is therefore possible that the idea of humans turning into wolves might be somewhat related to this idea. read more
Many shamanic traditions involve the spiritual transformation from human to animal, often through use of one or other of the naturally occurring psychotropics. It is possible, even likely, that this may be the basis of the werewolf myth (ergot poisoning gives the feeling of transformation). read more
This is likely how the 'werewolf' legends arose." —The Book of Dog Magic Stories of werewolves and their process of transformation have been with us for thousands of years; my discovery is that the historical and mythic roots seem to directly connect with the Horned God and shamanic practices. read more
Shamanism is also widespread and local cultures vary greatly, so this is only one feature in shamanism and can’t be generalized to be common in all shamanistic cultures. My vague knowledge is from reading a couple of books of Juha Pentikäinen, the former professor of Comparative Religion in the University of Helsinki ( Juha Pentikäinen), and the related articles that I can’t name anymore. read more