Learn English – the origin of “that’s using your noggin”

In Old Norse, Ratatoskr means "drill-tooth" or "bore-tooth". It is the name of a mythical creature, a squirrel that runs up and down the tree of life called Yggdrasil, acting as a messenger between two arch enemies: the great eagle and the terrestrial dragon.

According to Albert Sturtevant, "[as] far as the element Rata- is concerned, Bugge's hypothesis has no valid foundation in view of the fact that the [Old Norse] word Rata (gen. form of Rati*) is used in Háv[amál] to signify the instrument which Odin employed for boring his way through the rocks in quest of the poet's mead [...]" and that "Rati* must then be considered a native [Old Norse] word meaning "The Borer, Gnawer"

_Wikipedia

One can therefore assume that the word rat stems from a description of its behaviour.

I hesitate to take this topic even farther afield, yet getting at the origin may take it there.

An unsupported article by Frank Mulligan titled "The exciting history of the exclamation mark!" (Taunton Daily Gazette, Feb. 22, 2010), makes these claims:

Archeologists believe they identified the first pre-historic exclamation mark in a cave painting unearthed in northern France depicting a lone, proud hunter poised to hurl a spear at a wooly mammoth on one wall’s face.

On the opposing face of the cave’s wall, as one proceeds deeper into the interior, the scene depicts a lone, not-so-proud hunter trampled underneath a wooly mammoth followed by that unmistakable symbol: a dot topped by a line pointing skyward.

...

The exclamation mark’s first apparent use in writing dates back more than 5,000 years to the Egyptian hieroglyphs adorning the burial chamber in the Great Pyramid of Cheops at Giza.

The passage preceding what Egyptologists are convinced is the first exclamation mark used in an actual sentence translates roughly as: “It took a lot of work to build this thing!”

... there is evidence that Homer would break off during particularly exciting portions of “The Odyssey” to stand on a round rock and clasp both of his hands together over his head, much as a modern cheerleader will do to signify the letter “I,” in order to approximate an exclamation mark for his audience.

For my part, I'm willing to accept cave paintings as a form of writing. However, the lack of support for this account may indicate it is as fanciful as the account featuring a highly mobile 'io'.

More recently (2 September 2015), a quite evidently well-researched and far from fanciful account by Keith Houston, available in an article titled "The mysterious origins of punctuation" at BBC's Culture site, traces the origins of the exclamation mark and other punctuation marks from a system devised in the 3rd century BCE by an Egyptian librarian named Aristophanes.

Aristophanes' system used three dots:

... aligned with the middle (·), bottom (.) or top (·) of each line. His ‘subordinate’, ‘intermediate’ and ‘full’ points corresponded to the pauses of increasing length that a practised reader would habitually insert between formal units of speech called the comma, colon and periodos. This was not quite punctuation as we know it – Aristophanes saw his marks as representing simple pauses rather than grammatical boundaries – but the seed had been planted.

By Houston's account, Aristophanes' system of dots was abandoned, never having been more than a method of marking pauses, before being resurrected by Christians in the 6th Century:

As it spread across Europe, Christianity embraced writing and rejuvenated punctuation. In the 6th Century, Christian writers began to punctuate their own works long before readers got their hands on them in order to protect their original meaning.

The early Christian punctuation was, however, confined to

... decorative letters and paragraph marks (Γ, ¢, 7, ¶ and others)

until, in the 7th Century, Isidore of Seville

rearranged the dots in order of height to indicate short (.), medium (·) and long (·) pauses respectively.

Moreover, Isidore explicitly connected punctuation with meaning for the first time: the re-christened subdistinctio, or low point (.), no longer marked a simple pause but was rather the signpost of a grammatical comma, while the high point, or distinctio finalis (·), stood for the end of a sentence.

Now writers began to embellish the three-dot system:

Some borrowed from musical notation, inspired by Gregorian chants to create new marks like the punctus versus (a medieval ringer for the semicolon used to terminate a sentence) and the punctus elevatus (an upside-down ‘;’ that evolved into the modern colon) that suggested changes in tone as well as grammatical meaning. Another new mark, an ancestor of the question mark called the punctus interrogativus, was used to punctuate questions and to convey a rising inflection at the same time (The related exclamation mark came later, during the 15th Century.)

Having traced these origins, however, Houston glances over any individual account of the exclamation point:

This, then, was the state of punctuation at the height of the Renaissance: a mixture of ancient Greek dots; colons, question marks, and other marks descended from medieval symbols; and a few latecomers such as the slash and dash. ... when printing arrived in the mid-1450s, with the publication of Johannes Gutenberg’s 42-line Bible, punctuation found itself unexpectedly frozen in time. Within 50 years, the majority of the symbols we use today were cast firmly in lead, never to change again: Boncompagno da Signa’s slash dropped to the baseline and gained a slight curve to become the modern comma, inheriting its old Greek name as it did so; the semicolon and the exclamation mark joined the colon and the question mark; and Aristophanes’s dot got one last hurrah as the full stop.

Houston's account is not necessarily at odds with other accounts, but he does seem far less inclined to speculative flights of fancy based on hesitation marks and scribal errors in ancient manuscripts. Additionally, he doesn't pair images of these unerasable and possibly accidental artifacts made on very expensive 'paper' with speculative graphics depicting the 'evolution' of...the question mark?