Информация обламывается, как мне кажется. Почитал википедию:
"The notion that Nordic Vikings used the fly agaric mushroom to produce their berserker rages was first suggested by the Swedish professor Samual Ödman in 1784. Ödman based his theory on reports about the use of fly-agaric among Siberian shamans."
Ок, нашаманили, но далее:
"In addition, the injection of bufotenine from Bufo marinus toad skin into humans was shown to produce similar symptoms to the "Berserker" descriptions. These findings, first examined by Howard Fabing in 1956, were later linked to the induction of zombie characteristics by ethnobotanists in 1983."
"A UK television programme in 2004 tested the possible use of fly agaric and alcohol by training a healthy volunteer in the use of Viking weapons, then evaluating his performance under the influence of fly agaric or alcohol compared to no influence. It was shown that use of fly agaric or alcohol severely reduced his fighting ability, and the tentative conclusion drawn was that berserk state was achieved psychologically; otherwise, berserkers would have been too easy to kill."
Сердцу же всего милее:
"A simple theory attributes the behavior to drunken rage. It is also possible that berserkers worked themselves into their frenzy through purely psychological processes, perhaps using frenzied rituals and dances. According to Saxo Grammaticus they also drank bear or wolf blood."
В общем мнений много, а фактов не особо. Похоже придется проверят все на своей шкуре. :)
Кому интересно: http://en.wikipedia.org/wiki/Berserker