The Viking Berserkers – Brave warriors or drug-addicted?

Nowadays we often use the word "Berserk" or "to go berserk" to label any person in a irrational state of mind, or a person who isn't able to control his/her actions because the rage is such, that the person enters a frenzy, lunatic state, a destructively person or frenetically violent. The word Berserker or Berserk, comes from the old Norse word "Berserkr", which means "a wild warrior or champion". These warriors wore hides of bears, which might explain the origin of the berserkr as a compound of "Bera" - Bear, and "Serkr" - shirt or coat. These were the fierce viking warriors who were known for battling in an incontrolable trance-like rage, and were alleged to be able to perform seemingly impossible super-human feats of strength, akin only to a wild beast.

In the medieval history and folklore, of both Norse and Germanic, the berserkers were described as members of an unruly warrior band/gang, whose main devine cult was the cult of Odin, the king of the Aesir tribe of gods. The berserkers were also commissioned to royal and noble courts as bodyguards and special elite troops, who would strike fear into all who encountered them.

It wasn't hard to struck fear into the hearts of the enemies, as the berserkers behaved like an animal, roaring, grunting and howling, entering in a state of uncontrollable rage. Most of them would leap towards the enemy, biting shields and gnawing upon the skin of their enemies. 

Dating back as far as the ninth century, the berserker Norse Warriors were said to be able to do things that normal humans could not. According to ancient legend, the berserkers were indestructible, and no weapon could break them from their trance.  They were described as being immune to fire and to the strike of a sword, continuing on their rampage despite injury.

Most anthropological and psychological studies indicate that the Berserkers simply worked themselves up into a self-induced hysteria before fighting, that was part of the cult to Odin, very violent. They would act like animals, abandoning their clothes and dress with animal pelts, an initiation process to leave behind the human condition and become an animal. Other researches indicate that the consumption of drugs or alcohol, or even mental illness, could be the key to understand their behaviour. Some botanists have claimed that berserker behaviour could have been caused by the ingestion of the plant known as bog myrtle, one of the main spices in Scandinavian alcoholic beverages.

Other more esoteric theories surround supernatural beliefs. For instance, some scholars have claimed that the Vikings believed in spirit possession and that berserkers were possessed by the animal spirits of wolves or bears. According to some theorists, berserkers learned to cultivate the ability to allow animal spirits to take over their body during a fight (an example of animal totemism) that also involved drinking the blood of the animal that they wished to be possessed by.
Speaking in a more esoteric term, there are some theories surrounded by supernatural beliefs.For instance, some scholars have claimed that the Vikings believed in spirit possession and that berserkers were possessed by the animal spirits of wolves or bears. According to some theorists, berserkers learned to cultivate the ability to allow animal spirits to take over their body during a fight, an ancient cult of animal totemism linked to shamanism, that also involved drinking the blood of the animal that they wished to be possessed by.

In 1015, Jarl Eiríkr Hákonarson of Norway outlawed berserkers. The Grágás, the medieval Icelandic law code, sentenced berserker warriors to outlawry. By the 12th century, organised berserker war-gangs had been completely disbanded.