What is it about food and the human head that makes them constant companions? The head has been called the noodle, the loaf, the bean and other food-related terms, although – more on this in a moment – they didn't all begin as food references.
When the 16th-century painter Giuseppe Arcimboldo created heads from artfully assembled fruits and vegetables, he divined the truth that we are what we eat. Shakespeare's head-related insults included tripe-visaged (having a face like a cow's stomach) and beef-witted. In his book Carnal Knowledge, Charles Hodgson says even the Old English word for head, heafud, "is thought to have been pronounced something like 'hey-ya-food.'"
Reader John Boylan triggered this line of investigation with a note about noodling. A friend had sent him a letter with this sentence: "I'm also attaching my latest script, which I had noodled about for some time and have finally drafted." Boylan wrote: "I thought the word 'noodle' would be interesting for you to explore."
Noodle came to English by several routes. The string of pasta, for instance, was called a noodle from the late 1770s because of the German Nudel, and is probably related to knodel, dumpling.
From 1720, a noodle was a stupid person, but nobody is sure how that sense emerged. The leading candidate is noddle (perhaps related to a nod of the head), which had meant the back of the head since the 1400s and the head itself since the 1500s. Kingsley Amis used it in his 1984 novel Stanley and the Women: "a bald noddle with flowing locks down to his shoulder on one side only."
By 1762, the noodle referred to the head itself, stupid or otherwise. Laurence Sterne used it in (short title) Tristram Shandy: "What can have got into that precious noodle of thine?"
In other words, the noodle as head probably had nothing to do with the noodle as pasta, although the association is amusing when phrased as an insult. "Use your noodle" – smarten up, dummy – works best if the image is of a hollow piece of dough.
The same goes for bean, which dates from Old English in the sense of a legume but didn't refer to the head until around 1900, when a bean ball in baseball was a pitch that struck a batter on the bean. The head, after all, was shaped like a bean. It was tailor-made for the slang-rich works of P.G. Wodehouse. "Have I got to clump you one on the side of the bean?" asked a character in the 1924 novel Bill the Conqueror.
The word cropped up during the First World War in the expression "old bean," as a friendly reference to a man, albeit tinged with upper-class stuffiness (I say, old bean, frightfully good to see you). It has been suggested that this use of bean may be a corruption of being (as in human being). Place your bets.
To use your loaf is to use your head. It's rhyming slang: loaf of bread, head, in the same way that apples are stairs and porkies are lies (apples and pears, stairs; pork pies, lies).
Despite all of the above, the sense in which Boylan's friend used "noodle" may have its own, distinct origin. To noodle around on something, while it does make use of the noodle (head), may derive from the regional German nudeln, to improvise a song, or from the late-19th-century Scottish sense of noodling as humming a song to oneself. By 1937, to noodle was to fool around with notes to create music. By 1942, perhaps by association with the doodle (a loose, free-associating drawing), it acquired the broader sense of messing about with words or ideas without a clear goal.
Caution: Using your noodle or loaf is high in carbohydrates. Using your melon is less so. If you're on a true low-carb diet, beef-witted is the way to go.