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Who Were the Berserkers?

Donate These mighty Norse warriors fought with a frenzy that seems all but inexplicable.  

by Brian Dunning

Filed under History & Pseudohistory

Skeptoid Podcast #557
February 7, 2017
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Who Were the Berserkers?

For centuries, the Norse Berserker warriors have been regarded with a sort of mystique. They were said to fight like crazed animals, out of their minds, fearless, contemptuous of friend or foe, virtually undefeatable in combat. We get our modern English word berserk from them, meaning "violently or destructively frenzied; wild; crazed; deranged". A whole mythology has arisen surrounding the berserkers: Who were they? What was the true nature of their berserking? What was the source of their ability? Today we're going to don iron helmets and cast ourselves into the abyss of battle, and encounter the real berserkers.

Theories abound about how the berserkers got so berserk. Did they simply get really drunk before going into battle? Was it some kind of trance? One of the more popular explanations is that they took a form of hallucinogenic mushroom. But before we look into the theoretical, let's look at the factual. What do we actually know about the berserkers, and how do we know it?

The berserkers are known from their numerous mentions and descriptions in the sagas, the epic Icelandic stories of Vikings written in Old Norse, primarily in the 10th through the 14th centuries. The word comes from ber-serkr, usually interpreted to mean bear shirt, as in wearing a bearskin for a shirt. Less popular interpretations have been no shirt, or animal skin, basically meaning no armor. Regardless, the net result is the same. Berserkers were generally described as wearing no armor or mailcoats, and wearing the head or pelt of a bear, wolf, or boar either on their head directly or on a helmet. Such costumes have long been used as a battle strategy to invoke terror; and indeed, the most famous appearance of berserkers in the sagas was as shock troops employed by King Harald Fairhair, the first King of Norway, circa the year 900.

The berserkers' association with animal pelts has led some of the mythology astray into comparisons with shapeshifters, such as werewolves or skinwalkers. And that's not really what they were, because they were real Vikings, and those things are not things. Author Richard John King, writing in an 1850 edition of the literary journal Notes and Queries, summarized the Danish report of the controversial Viking scholar Grímur Jónsson Thorkelin:

Thorkelin, in his essay on the Berserkir, appended to his edition of the Kristni-Saga, tells us that an old name of the Berserk frenzy was hamremmi, i.e., strength acquired from another or strange body, because it was anciently believed that the persons who are liable to this frenzy were mysteriously endowed, during its accesses, with a strange body of unearthly strength. If, however, the Berserk was called on by his own name, he lost his mysterious form, and his ordinary strength alone remained.

It is clear, therefore, continues Thorkelin, that the state of men laboring under the Berserk frenzy was held by some, at least, to resemble that of those, who, whilst their own body lay at home apparently dead or asleep, wandered under other forms into distant places and countries. Such wanderings were called hamfarir by the old northmen; and were held to be only capable of performance by those who had attained the very utmost skill in magic.

And such is the direction taken by much 19th and 20th century research on the berserkers. I'm not going to follow that thread today, but it's out there if you want to pursue it independently. There is a somewhat interesting history of how the berserkers may have informed modern folklore about shapeshifters and associated magic. It's their actual abilities and nature that we're going to focus on today.

The so-called frenzy or rage into which a berserker would go was called berserkergang (bärsärkar-gång). Snorri Sturluson, a prominent author of the sagas, described it thus:

Men rushed forwards without armour, were as mad as dogs or wolves, bit their shields, and were strong as bears or wild bulls, and killed people at a blow, but neither fire nor iron told upon themselves. These were called Berserker.

How could ordinary men become so supernaturally vicious? Most modern explanations for berserkergang invoke the hallucinogenic Fly Agaric mushroom, Amanita muscaria. I find this a poor theory, for three reasons. First, with all the discussion of berserkergang in the sagas, there is never once a mention of eating or drinking anything to trigger it. It just happened, spontaneously. Second, there are analogs for berserkergang in many cultures around the world, and no mushrooms (or anything else) are needed to trigger those either. It's called amok syndrome in Malay and Indonesian cultures, giving us our word amok. It's mal de pelea in Puerto Rico, grisi siknis in Central America, and simply the "fits" in India. Even the Inuit have something called pibloktoq, thought to be triggered by the stress of the long winter nights. No mushrooms are available on the ice. And third, the mushroom theory is very poorly sourced. It was suggested by the Swedish theologian Samuel Ödmann in 1784, based on stories about Siberian shamans using it for visions. There was never anything to connect the mushrooms to the Vikings or to any behavior similar to berserkergang. It is a theory devoid of evidence or plausibility, yet it remains the most often repeated.

One interesting theory meshes relatively well with modern psychology. Being in medieval battles was probably a pretty horrifying experience, and likely to take a psychological toll on those who witnessed things like this (from Egil's Saga):

He wielded his axe and struck Hallvard right through his helmet and head... Then he tugged it back with such force that he swung Hallvard up into the air and slung him over the side...

Consider this minor episode in the same story, where Egil was playing a game with his friend Thord and father Skallagrim. With no provocation:

Skallagrim was seized with such strength that he seized Thord and dashed him to the ground so fiercely that he was crushed by the blow and died on the spot. Then he seized Egil...

...and would have killed him too, but for the interference of a servant woman, whom he killed instead, by throwing a boulder at her. Considering Skallagrim's history of hand-to-hand combat, forced upon him by his station in life, a psychologist today wouldn't even have to think twice to say "Posttraumatic Stress Disorder". Skallagrim's violence against his family and friends for no reason is a classic dissociative reaction, beyond his control, triggered by something in the play.

Important note: PTSD presents in many different ways, and this would be only a very extreme manifestation. The vast majority of people suffering from PTSD never do anything remotely like this. I am pointing this out to head off inevitable criticism that I am painting all PTSD sufferers as bloodthirsty killers, which is neither true, nor a reasonable interpretation of this episode. —BD

In 1956, Howard Fabing described the berserkergang in the American Journal of Psychiatry:

Men who were thus seized performed things which otherwise seemed impossible for human power. This condition is said to have begun with shivering, chattering of the teeth, and chill in the body, and then the face swelled and changed its colour. With this was connected a great hot-headedness, which at last gave over into a great rage, under which they howled as wild animals, bit the edge of their shields, and cut down everything they met without discriminating between friend or foe. When this condition ceased, a great dulling of the mind and feebleness followed, which could last for one or several days.

PTSD had not yet been described in 1956, but what Fabing described is a nearly textbook example of what we would now recognize as a severe PTSD episode. It can begin with an almost seizure-like dissociated state of consciousness, followed by reckless behavior that can be violent and self-destructive, and afterwards, a period of deep depression. (And again, I emphasize, this would be a very rare manifestation of PTSD.)

Another important clue is Fabing's mention that berserkers did not seem to know friend from foe. This is found in a number of places in the sagas, and so, evidently, was a common feature of the mania. During a dissociative episode, the person often does not know where they are, or recognize people, or retain any memory of the episode. It is a key piece of evidence that PTSD is indeed a likely cause of what history has termed a berserkergang.

During a severe PTSD episode, the body goes into hyperarousal, also called the acute stress response, or fight-or-flight. Adrenaline is dumped into the bloodstream. This is how I described it in our episode about "Superhuman strength during a crisis":

Your airways relax to maximize breathing capacity, and metabolism increases. Your muscles go into glycolysis, which produces energy-rich molecules fueling them for extraordinary action. While blood flow to the muscles is increased, blood flow to vulnerable extremities is decreased. Endorphins are produced in the brain as a natural pain killer. Peripheral vision turns into tunnel vision to minimize distractions. Reflexes and reaction times improve. Non-critical functions like digestion and sexual function slow or even stop.

It is the complete set of skills a warrior in berserkergang needs. It's what one needs to throw Hallvard overboard by the axe buried in his head. It's what one needs to fight a battle with an apparent imperviousness to injury and pain.

Saga historians have noted that being a berserker and the act of berserkergang are two different things. In the sagas, the act of berserkergang is mentioned more often, and usually in different places, than are actual berserkers. We might interpret this to mean that going berserk is something that was well known, which, if we accept the theory that PTSD was involved, would certainly be the case in a culture that was so frequently engaged in violent combat. We might further hypothesize that, in recognition of the fact that this seemed to happen a lot to many warriors, certain of them became anointed as berserkers, and regarded as specially talented. It is not an unreasonable conclusion for a pre-scientific society to reach. And, once you have a subclass of warriors with a special name known for a special ability, identified by bearskins, there you have a springboard for all the shapeshifter mythology that followed. Again, not a horrible interpretation by prescientific people struggling to explain how men could suddenly act so differently.

Could it be that the mighty berserkers of Viking sagas were nothing more or less than ordinary men suffering from a very real psychological disorder? The evidence does indeed seem to fit; each box is checked all the way down the list. The life of a warrior armed with horrible weapons like axes and longswords could not have been a very happy one, and it could just be that the berserkers were merely those who felt it most keenly. Might they have been more deserving of our sympathy than of our fear?

By Brian Dunning

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Cite this article:
Dunning, B. "Who Were the Berserkers?" Skeptoid Podcast. Skeptoid Media, 7 Feb 2017. Web. 24 Apr 2024. <>


References & Further Reading

APA. Diagnostic and Statistical Manual of Mental Disorders: Fifth Edition. Washington DC: American Psychiatric Publishing, 2013. 271-280.

Fabing, H. "On Going Berserk: A Neurochemical Inquiry." American Journal of Psychiatry. 1 Nov. 1956, Volume 113, Issue 5: 409-415.

Mason, E. "The Truth about Viking Berserkers." History Extra. Immediate Media Company Limited, 15 Sep. 2016. Web. 29 Jan. 2017. <>

Rees, O. "Going Berserk: The Psychology of the Berserkers." Medieval Warfare. 9 Mar. 2005, Volume II, Issue 1: 23-26.

Siebert, E. "Going Berserk." Skeptical Humanities. Bob Blaskiewicz, Eve Siebert, Mark Newbrook, & Jenna Marie Griffith, 19 Apr. 2011. Web. 29 Jan. 2017. <>

Vitelli, R. "Going Berserk." Providentia: A biased look at psychology in the world. Romeo Vitelli, 26 Jul. 2009. Web. 27 Jan. 2017. <>


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