The story of Santa and his flying reindeer can be traced to an unlikely source: hallucinogenic or "magic" mushrooms, according to one theory.
"Santa is a modern counterpart of a shaman, who consumed mind-altering plants and fungi to commune with the spirit world," said John Rush, an anthropologist and instructor at Sierra College in Rocklin, Calif.
Here are eight ways that hallucinogenic mushrooms explain the story of Santa and his reindeer.
1. Arctic shamans gave out mushrooms on the winter solstice.
According to the theory, the legend of Santa derives from shamans in the Siberian and Arctic regions who dropped into locals' teepeelike homes with a bag full of hallucinogenic mushrooms as presents in late December, Rush said.
"As the story goes, up until a few hundred years ago, these practicing shamans or priests connected to the older traditions would collect Amanita muscaria (the Holy Mushroom), dry them and then give them as gifts on the winter solstice," Rush told LiveScience in an email. "Because snow is usually blocking doors, there was an opening in the roof through which people entered and exited, thus the chimney story."
2. Mushrooms, like gifts, are found beneath pine trees.
The Amanita muscaria mushroom, which is deep red with white flecks.
That's just one of the symbolic connections between the Amanita muscaria mushroom and the iconography of Christmas, according to several historians and ethnomycologists, or people who study fungi's influence on human societies. Of course, not all scientists agree that the Santa story is tied to a hallucinogen.
3. Reindeer were shaman "spirit animals."
Reindeer are common in Siberia and northern Europe, and seek out these hallucinogenic fungi, as the area's human inhabitants have also been known to do. Donald Pfister, a Harvard University biologist who studies fungi, suggests that Siberian tribesmen who ingested fly agaric may have hallucinated that the grazing reindeer were flying.
4. Shamans dressed like … Santa Claus.
These shamans "also have a tradition of dressing up like the [mushroom] … they dress up in red suits with white spots," Ruck said.
5. Mushrooms abound in Christmas iconography.
Tree ornaments shaped like Amanita mushrooms and other depictions of the fungi are also prevalent in Christmas decorations throughout the world, particularly in Scandinavia and northern Europe.
7. "A Visit from St. Nicholas" may have borrowed from shaman rituals.
Many of the modern details of the modern-day American Santa Claus come from the 1823 poem "A Visit from St. Nicholas" (which later became famous as "'Twas the Night Before Christmas"). The poem is credited to Clement Clarke Moore, an aristocratic academic who lived in New York City.
The origins of Moore's vision are unclear, although Arthur, Rush and Ruck all think the poet probably drew from northern European motifs that derive from Siberian or Arctic shamanic traditions.
8. Santa is from the Arctic.
"People who know about shamanism accept this story," Ruck said. "Is there any other reason that Santa lives in the North Pole? It is a tradition that can be traced back to Siberia."