You Are What What You Eat Eats

A few days ago I came across a quotation attributed to author Michael Pollan:

You are what what you eat eats, too.

After some Googling, I confirmed that Pollan did write this; it appears in two of his books. In 2008’s In Defense of Food: An Eater’s Manifesto, he writes on p. 167:

“You are what you eat” is a truism hard to argue with, and yet it is, as a visit to a feedlot suggests, incomplete, for you are what what you eat eats, too.

In 2006’s The Omnivore’s Dilemma: A Natural History of Four Meals, You are what what you eat eats is the title of a section beginning on page 84. Though the sentence is now associated with Pollan, he wasn’t the first to construct it. Google Books also turned up a 1985 attestation, from page 80 of the novel Dreams of Sleep by Josephine Humphreys:

“You are what you eat,” said a crazy woman, and another one said, “You are what what you eat eats.”

Linguists love sentences like You are what what you eat eats, as examples of center-embedding found in the wild, not created just to illustrate the concept of center-embedding. But what is center-embedding, anyway, and why is it so interesting?

First, take a sentence like I know you believe you understand what you think I said. If we look at a diagram of it, we can see that we have five sentences nested one inside the other. (The subscript 1 after what corresponds to the 1 following said, showing where the wh-word would go if English didn’t require it to go at the front of its clause.) Also notice how we can break one word off the tree at a time, starting on the left, by removing the successive left branches of the tree. This kind of structure is said to be “right-branching”. In a right-branching structure, as in the fortune cookie game, the embed goes at the end.

A right-branching structure

A left-branching structure

There’s such a thing as a left-branching structure, too. A good example is my mother’s friend’s dog. Let’s diagram that. Notice that we have three noun phrases, one inside the other, and notice how we can remove one word at a time from the diagram, starting on the right, by breaking off successive right branches of the tree.

Neither of these structures is too hard to parse, even though the deepest-embedded sentences or noun phrases are several layers down in the tree. Now let’s take a simplified version of Pollan’s sentence: You are what something-or-other eats. Right now, we have two sentences, one nested inside the other, and it’s pretty easy to parse. If something-or-other were a single word, this sentence would be completely right-branching.

A simplified version of Pollan's sentence

Now let’s replace something-or-other with a different noun phrase. In fact, let’s replace it with a noun clause, which is basically a sentence that’s allowed to do syntactic duty as a noun phrase. Specifically, let’s replace it with the noun clause what you eat. This structure is neither right-branching nor left-branching. The noun clause we embedded went right into the middle of the structure; hence the name center-embedding. Notice that this is getting difficult to parse, even though we have only three nested sentences, fewer than the five in our right-branching example. It’s not ungrammatical, but a copyeditor might flag it as bad style because it trips up the reader. In Pollan’s case, I think this is a deliberate effect: He wants us to slow down and take a few seconds to construct and absorb the meaning of the sentence.

Pollan's sentence

Now, you know what linguists (or at least syntacticians) like to do when they find a center-embedded structure? Center-embed some more stuff in it! I’m going to take that you and replace it with a noun clause again. Let’s see, what should we put in there? Whoever likes classical music? What the butler saw? No, I know: We’ve had so much fun with what you eat, why not use it again? Here we go:

Center-embedded chaos

At this point, with only four nested sentences, we have produced something that’s almost completely unintelligible. BTW, I’m not the first one to have done this to Pollan’s sentence: Emily Bender beat me to it in her course notes for a computational linguistics class last fall (see page 16). (What did I tell you about linguists when they find a center-embedded structure?) Anyway, I say this sentence is almost unintelligible because you just might be able to intellige it if you wrote it down and really concentrated on it for a minute or two. Or you might just think that the speaker had a bad stutter, and mentally correct the sentence to You are what you eat. But is it ungrammatical? Center-embedding is not ungrammatical per se, as we saw above, and multiple embeddings are not bad, as the right- and left-branching examples showed. So why shouldn’t multiple center-embedding be grammatical? Maybe it’s just this sentence that sounds so bad, because we kept using the same subjects and verbs. But no: The rat the cat the dog bit chased escaped is more like the prototypical example of a linguist-generated center-embedded sentence, and it’s equally difficult to parse, if not more so. The point linguists like to make with center-embedding is that the set of phrases our grammar rules can generate and the set of things our minds can actually keep hold of long enough to process are not identical sets.

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