We were talking about comparative/ psychological schools of thought and how the New Age ideas of Campbell are not too respected any more (at least, anyone following in Campbell's footsteps doesn't hold much weight in the academic realm). This is a little discouraging to me, because I love the concept that narratives/ mythologies are universal and driven by the basic, psychological desires of humans.
The root question, though "why do myths share similarities across cultures?" is still interesting to me, even if the answer isn't some deep, spiritual thing. We got onto talking about the conflict between the gods and giants, and the war between the warrior gods (Aesir) and the fertility gods (Vanir) and why such a mythological system would be in place (and why, for example, is there also a god-giant conflict... god/ titan... in Greek Myth). The answer was rooted in the structure of the society - the struggle for power of the 'producer' class of farmers (represented as Vanir) and the warrior/ priest class (represented as the Aesir).
Since the warrior/ priest class was more dominant in these indo-european cultures, this seems like a good reason why the Aesir are much less mysterious in their names and family tree (Odin, Thor, Balder, Heimdall....)
That led to a discussion on why the cosmology of the Norse universe existed the way it did - the 9 world concept with a central tree Yggradsil (an Axis Mundi). This is what really intruiged me. While the Aesir/ Vanir/ Giant conflicts can be traced to class structure and seem to evolve as indo-europeans spread across the continent, the concept of an Axis Mundi linking the heavens and the earth exists pervasively across the world.
Professor Gull explained to me that this concept has its roots in Shamanistic thought/ practice, which is a form of religion much older and much more universal than Celtic, Greek, or Norse mythology. Kind of like "layer 1" in the build up of Norse myth, which can be rooted in psychology and exist across the world because of the innate desires of humans. Shamanistic practice (the way I understand it) often involves separating the mind from the body and sending out one's spirit to communicate with the gods/ the dead/ animals/ etc. Yggdrasil, or any cosmic world pillar, serves as the channel/ path to connecting between the worlds is traversed by these few who are capable of separating mind and body.
I think this concept, of separating mind from body, may arise as a result of the phenomenology of dreaming, which is a highly influential aspect of most (all?) world cultures/ religions.
I've already been diving into research with some interesting results, and I'm looking forward to examining other Axis Mundis from other world religions/ mythologies/ etc....