The Defenseless Metaphor: Pyramid of Life

If Metaphor Man were a real superhero, surely one of his tasks would be to deliver justice on behalf of misused metaphors. One such metaphor, the “pyramid of life,” was unfairly maligned in a New York Times editorial on Tuesday about predator-prey relationships in the animal world.

“Like most simple metaphors, this one has a perceptual flaw,” the editorialist wrote. “It creates the illusion that large predators have an effect only on the prey species immediately below them.” However, recent observations by biologists show that species lower on the food chain are also dependent on healthy populations of predators above them, which the metaphor doesn’t communicate.

First, Metaphor Man has to check the identity of the misused metaphor. Ah, yes, here’s an undated version the National Park Service put together for 6th graders:

How common is the “pyramid of life” metaphor? Surely the metaphor comes from a time when people saw grasses and eagles as unrelated. This was a time when the understanding of ecological systems was young, if non-existent, in the public mind. Indeed, a quick Web search reveals that the pyramid has long been replaced by “food web” (which supplanted the “food chain” of Metaphor Man’s own biology education). The “pyramid of life” isn’t as common a metaphor as the editorial writer thinks.

Metaphor Man knows that when deadline time looms, it may be too much to expect editorial writers to know which science metaphors are state-of-the-art and which ones are obsolete. This is especially true when an article with no obvious news hook needs a snappy lede. That doesn’t mean he has to like metaphor-stomping as a go-to literary device. And metaphors, he might add, do not possess “perceptual flaws,” as metaphors do not perceive; the flaws of perception, alas, are thoroughly human.

On the other hand, these editorial follies provide an excellent example of why FrameWorks tests its simplifying models. Had an ecologist come to us asking to for a way to capture dynamic, non-hierarchical links of dependencies among species of plants, animals, and microbes, we would have quickly ruled out “pyramid” as a candidate. It’s familiar, that’s true. But it’s also too top-down; it doesn’t capture change over time. Yet these aren’t “flaws” in the metaphor. We might say instead that the conceptual domain of pyramids doesn’t match up to enough of the science to be very useful (though we can imagine a state of the science in which a pyramid was more than enough, as I noted above).

Metaphor Man likes the direction that scientists have gone with “food web” — though he’d love to test it, all the same.

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