Ratatoskr ('Drill-tooth') has the cosmos's strangest job: he is the courier of a feud. Up the trunk of Yggdrasil to the unnamed eagle who sits at its top, down again to the dragon Níðhöggr gnawing the deepest root — carrying, Snorri says, 'slanderous words' between them, presumably improved in transit.
He is comic relief with a dark function: the world-tree that holds all things together is being chewed from below and quarrelled over from above, and the squirrel keeps the hostility circulating. Norse cosmology's picture of the world includes, built-in, a small tireless agent of malicious gossip.
The squirrel in the world-tree
To see why the mythology bothered with a squirrel, start with the tree. Yggdrasil, the great ash at the centre of Norse cosmology, is less a plant than an address system: the nine worlds are arranged around it, the gods hold their court beneath it, and its inhabitants map the moral structure of everything. At the crown sits an eagle, credited with knowledge of many things, a hawk called Veðrfölnir perched between its eyes. At the bottom, beneath the root that reaches over Niflheim, the dragon Níðhöggr gnaws eternally, in company with more serpents — Grímnismál insists — "than any fool imagines." Four harts browse the branches; the tree's side rots; hardship assails it at every level.
And connecting top to bottom, the only traffic on the trunk, runs Ratatoskr. The Eddic poem Grímnismál gives him a single stanza, and it is nearly everything we have: "Ratatoskr is the squirrel's name, who shall run on the ash Yggdrasil; the eagle's words he shall carry from above and tell to Níðhöggr below." Snorri Sturluson, systematising the cosmos in Gylfaginning, repeats the picture and sharpens the job description: the squirrel runs up and down the ash bearing öfundarorð — words of envy, spite, slander — between the eagle and the dragon. The poem mentions only downward delivery; Snorri makes the route two-way. Between them, that is the entire dossier: a name, a route, and a cargo of malice.
What does the name Ratatoskr mean?
The second element is the easier one: -toskr is generally taken as "tusk" or "tooth" — possibly, scholars have suggested, a borrowing related to Old English tusc, which would make the squirrel's very name a small piece of North Sea traffic. The first element is likelier connected with the verb rata, "to travel, find the way," or with boring and gnawing — and here the mythology offers a suggestive echo: Rati is the name of the auger with which Odin bored through the mountain Hnitbjörg to steal the Mead of Poetry. "Drill-tooth" or "Bore-tooth" is therefore the usual rendering — a perfect squirrel's name, for an animal that opens hazelnuts like a locksmith, and perhaps a sly one: the creature named for boring-through spends eternity boring holes in the peace.
None of this is certain; the etymology, like everything about Ratatoskr, is argued from two short texts and comparative philology. But the name's whole flavour — small, sharp, penetrating — is not in doubt.
Why does a squirrel run up and down Yggdrasil?
The sources never explain Ratatoskr's motive, and that silence has made him a favourite of interpreters. Several readings coexist, and honesty requires laying them side by side rather than picking a winner.
The plainest is ecological: anyone who has watched a red squirrel spiral chattering up a Scandinavian pine has met Ratatoskr's model. Squirrels do scold; they do run trunk-roads all day; a mythology that furnished its world-tree with harts, an eagle, and serpents naturally hired a squirrel for the trunk. On this reading the myth is close observation of a real tree's fauna, scaled up to the tree of everything.
The second reading is social, and darker. Norse culture took verbal malice seriously enough to legislate against it: slander, insult-verse, and níð — formal dishonour — could get a poet outlawed or killed, and the flyting (the ritual exchange of insults) was practically a literary genre, with Loki's performance in Lokasenna its masterpiece. A cosmos built by that culture includes, as standing equipment, a carrier of insults — because in that culture's experience, every community had one. Ratatoskr is the gossip who keeps two parties who never meet perfectly furious with each other. The eagle at the crown and the dragon at the root have no natural contact; their hatred is entirely mediated, and the mediator is the message. Some commentators go a step further and note that the squirrel's traffic binds the tree's extremes together: even hostility, endlessly circulated, is a kind of connection, and the world-tree's unity includes its quarrels.
A third reading takes the squirrel as deliberate comic relief — the one small, quick, undignified thing in a cosmology of wolves, serpents, and doom, proof that the mythographers had a sense of humour about their own architecture. These readings are not exclusive. A culture can observe a squirrel, recognise a gossip, and enjoy the joke, all in one stanza.
In the primary sources
Ratatoskr's entire textual existence consists of Grímnismál stanza 32 in the Poetic Edda and Gylfaginning chapter 16 in the Prose Edda, the latter partly quoting the former. He appears in no other poem, no saga, no skaldic kenning, and no known carving that can be identified with confidence. There is no story in which he does anything but run; he has no parents, no fate at Ragnarök, and no recorded speech — the one creature in the mythology defined by talking whose words are never quoted. Everything else written about him, including the paragraphs above, is interpretation, and readers should hold it exactly that lightly. That so slight an attestation has produced so vivid a character is itself the point: two sentences and a good name can outlast empires.
Legacy
For a creature with one stanza to his name, Ratatoskr has done spectacularly well in the modern age. He appears as a wisecracking companion in the God of War games, in Magic: The Gathering, in children's books and animated series, and as the affectionate mascot of more than one internet forum — the patron creature, appropriately, of message boards. Writers on social media have found him irresistible: a small tireless agent carrying inflammatory messages between parties who never meet face to face required no updating whatsoever. Eleven centuries early, the Norse drew the network diagram.
Frequently asked questions
What does Ratatoskr do in Norse mythology?
He runs up and down the world-tree Yggdrasil carrying messages — specifically slanderous, spiteful ones, according to Snorri — between the wise eagle perched at the tree's crown and the dragon Níðhöggr gnawing its lowest root. That is his entire recorded function.
What does the name Ratatoskr mean?
Most scholars render it "Drill-tooth" or "Bore-tooth": -toskr means "tusk, tooth" (possibly related to Old English tusc), and rata- is connected with travelling, finding a way, or boring through — the same root as Rati, the auger Odin used to bore into the mountain for the Mead of Poetry.
Why do the eagle and Níðhöggr hate each other?
The sources never say. The feud exists only in the fact of its messenger: Grímnismál and Gylfaginning describe the insult traffic but give no origin, no content, and no resolution. Many readers suspect the squirrel's deliveries are the feud — malice kept alive purely by circulation.
Is Ratatoskr good or evil?
The sources don't judge him. He is a courier of öfundarorð — "envious words" — which makes him an agent of discord, but he originates nothing and harms no one directly. Most interpreters read him as the mythology's gossip: not evil so much as indispensable to evil's distribution, with a comic edge the poets surely intended.
Where is Ratatoskr mentioned in the old texts?
In exactly two places: stanza 32 of the Eddic poem Grímnismál, and chapter 16 of Gylfaginning in Snorri's Prose Edda, which quotes and expands the stanza. He appears nowhere else in Old Norse literature.