Shrooms, and human blood. Nothing to do with bear gall bladders. They might have had a rite of passage killing the bear or wolf. But it wasn't the gauntlet, they'd practice in and run, or the shield walls they'd fight to the death in. Ultimately what psyched them was endurance, blood rituals, pagantry, and even human sacrifice. They took slaves, they human sacrificed. They believed their gods were immortal. Dying on the battlefields took them to Valhalla. If they took a potion for it, it had the shrooms.
I'll second this. I'm not a historian, but cannibalism was my initial hypothesis.
Drinking peoples blood probably would do it. Spongiform encephalopathies can present in humans as savagery, and prion disease can be caused by cannibalism.
Shrooms, and human blood. Nothing to do with bear gall bladders. They might have had a rite of passage killing the bear or wolf. But it wasn't the gauntlet, they'd practice in and run, or the shield walls they'd fight to the death in. Ultimately what psyched them was endurance, blood rituals, pagantry, and even human sacrifice. They took slaves, they human sacrificed. They believed their gods were immortal. Dying on the battlefields took them to Valhalla. If they took a potion for it, it had the shrooms.
I'll second this. I'm not a historian, but cannibalism was my initial hypothesis.
Drinking peoples blood probably would do it. Spongiform encephalopathies can present in humans as savagery, and prion disease can be caused by cannibalism.