One of the foremost virtues – probably the foremost virtue – of good scientific writing is clarity. (I make this argument at length in The Scientist’s Guide to Writing.) In service of this goal, writers are often advised to be cautious about using metaphors (see Olson, Arroyo-Santos, and Vergara-Silva (2019), A User’s Guide to Metaphors in Ecology and Evolution, for an interesting analysis of metaphors and their strengths and weaknesses). A metaphor names or describes one thing by referring to another, and our literature is studded with them*: the tree of life, the Big Bang, electron shells, biological invasions, chaperonins, tectonic plates – and these are just a few that came to my mind right away.
Critics of metaphors often rest their case on three major grounds. Metaphors are held to be vague, to be misleading, or to resist cultural translation. Do these grounds hold water?**
Are metaphors vague? Some metaphors famously are – perhaps none more so than the ecological niche, which can seem to mean something different in every paper. Olson et al. make the interesting claim that metaphors become vaguer as they age, accreting new interpretations without shedding any old ones. That’s might be true for “niche”, but it’s not actually an inevitable property of a metaphor. I don’t thing the Big Bang is less precise now than when it was coined; nor are chaperonins, the tree of life, or tectonic plates. The vagueness issue has little to do with the use of metaphor, really – instead, it’s concepts that are vague or precise. The set of things we collectively use “niche” for is broad and complex; but that’s not because we named them with a metaphor.
Are metaphors misleading? Sometimes, readers take the wrong message from a metaphor. The term “biological invasion” has been criticized on multiple grounds, one of which is that an invasion (in the familiar military sense) is a planned and deliberate action – something not true for the North American spread of the emerald ash borer. But literal applicability is a strangly misguided thing to ask of a metaphor. A metaphor draws attention to some shared feature of two things, while acknowledging that they are not literally the same. All the world’s a stage, Shakespeare told us, but few critics have complained that all the world is not made of wood. Writers and readers should of course both use metaphors with care, remembering that an evolutionary tree isn’t made of wood either, that the Big Bang didn’t make any sound, and that you can’t get your feet wet on an adaptive landscape. This shouldn’t be difficult. Good metaphors offer fewer opportunities for confusion; good writers are very clear about what they intend by one; and good readers are careful to think critically about a metaphor. All three things are true for every other rhetorical device. And metaphor is a routine way that words in English acquire new meaning. Nobody is terribly confused by reference to a middle-aged man’s spare tire, a bird’s song, or a broken-hearted lover.
Sure, metaphors have some downside risk, suggesting more things than the writer intends. But not using metaphors has downside risk too. If you don’t want the job of separating what you mean by a metaphor from what you don’t, you can always name your new concept with a neologism. Instead of “evolutionary tree”, we could have used “snickslefluver”. No risk of metaphorically induced confusion there – but not much help for a reader, either. A neologism route asks a reader to learn an entirely new term rather than building from something they already know; and it passes on an opportunity to make writing engaging and even – yes, this is OK – beautiful or entertaining.
Do metaphors resist cultural translation? Some objections to metaphors are more about equity, suggesting that metaphors may be less accessible to readers whose first language isn’t English, or whose cultural backgrounds differ from that of the writer. It’s certainly true that science is a global and multicultural enterprise, and that we’d do well to remember that in writing. But I have a feeling that metaphors may be a bit like contractions – which some native English speakers suspect of being difficult for readers of English as an additional language, but which aren’t seen as a problem by those EAL readers themselves. We sometimes confuse, shamefully, unfamiliarity with English with inability to handle it. And, of course, every language uses metaphor***. As an English speaker reading French, for example, I do need to learn new-to-me metaphors just as I need to learn new-to-me words; but they aren’t what makes reading scientific papers in French difficult. Complex sentences, overuse of acronymss, unnecessary jargon: if we want to make our writing more accessible to global readers, I suspect that any of those is a better target than metaphor.
As you can tell, I’m on Team (careful) Metaphor. I can’t let you go without sharing my very favourite use of metaphor in scientific writing. It’s not the Big Bang, or evolutionary trees, or even the Red Queen (despite my fondness for all things Lewis Carroll). It’s Matt Rockman’s (2012) use of the California gold rush to make a point about the modern search for quantitative trait nucleotides (single-base DNA substitutions that have measurable effects on the traits of organisms). Here’s an excerpt:
In January 1848, James Marshall found gold flakes in the millrace of John Sutter’s saw mill. Within months . . . the rush was on. Thousands left home, rounding the Cape, crossing the Isthmus, or joining the wagon trains headed west. Soon the easy pickings were gone, and consortia of miners banded together to blast more flakes from the hills. Extraction technologies proliferated: first rockers and long toms, then gravel dredges, and finally hydraulic mining, which washed whole mountains through giant sluices to recover dense gold flakes from the riffles.
Modern day QTN prospecting is the Sierra Nevada of the 1850s. The shiny (Mendelian) nuggets are rapidly being collected, and ever larger teams of researchers with ever more powerful technologies are now probing whole genomes to find their quarry. But visible flakes of placer gold represent a small fraction of the global gold reserve; most gold is in microscopic particles concealed in low-grade ore. If the stuff of evolution is often alleles of microscopic effect, large-effect nuggets can tell us little about the material basis for evolution. (Rockman 2012, Evolution 66:2)
It’s beautiful, it’s clear (even if you don’t know what rockers and long toms were), and it tells you something about QTNs that sticks with you because of the vividness of the telling. In our scientific writing, let’s be careful to use metaphor well; but let’s go on using it.
© Stephen Heard November 9, 2021
Image: Long tom sluice in a California gold field, circa 1849. Public domain, via US Library of Congress.
*^And in case you didn’t pick it up, “studded” is itself a metaphor.
**^Another metaphor, and a mixed one. For that matter, “metaphor” itself is a metaphor of a sort – the word’s roots in ancient Greek mean “other-carry”, and the carrying (of meaning) is metaphorical. How meta. I’ll admit that I’ve been fascinated by self-referential constructs (like “metaphor”) since my youthful infatuation with Gödel, Escher, Bach. But if I can’t use it to experience a little frisson of nerdly joy, what else is being meta for? (Ba-dum-tss.)
***^Which I typed and then realized it’s a “fact” I completely made up. But I bet it’s true.