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Editorial: Overextending metaphors can lead to communication breakdowns

by Geoff Hart

Previously published as: Hart, G.J. 2005. Editorial: Overextending metaphors can lead to communication breakdowns. the Exchange 12(2):2, 6. http://www.stcsig.org/sc/newsletter/html/2005-2.htm#editorial

As scientific communicators, we rely heavily on metaphors and other image-heavy text to communicate complex concepts. This can be a powerful tool for simplifying complexity, but unfortunately, significant problems arise when we lean too heavily on those images and forget about the consequences of carrying a metaphor too far. The problem lies in our attempt to make the complex simple: some concepts really are too complex to express simply, and oversimplifying them can create vexing communication breakdowns.

Paul Berg, interviewed in the April 2005 issue of Discover, illustrated the kind of problem that can occur when a word or image acquires a connotation that conceals the real meaning and the underlying complexity associated with that meaning:

"For example, the word cloning. What do you think resonates in the minds of the general public when a scientist says he wants to clone stem cells? Well, right away, they associate it with cloning people. But we're all agreed we shouldn't clone people... But the word cloning just triggers fears. What do you see? The Boys from Brazil, Star Wars."

A recurring example involves a cliché that has become part of the repertoire of popular science writing about genetics. One of the fascinating recent discoveries in molecular genetics is how strongly some genes have been conserved in different species despite thousands of years of evolution. Unfortunately, evolution is a complex science, and genetics even more so. Inevitably, this makes writing about both at the same time difficult. To simplify the task of communicating this complex interaction between evolution and gene conservation, authors usually try to demonstrate how similar humans are to other species by comparing our respective genomes. Thus, in studies of primates, you'll often hear the claim that chimps and humans share 99% of the nucleotide sequences in our respective genomes. This number sounds high, and indeed, each of us would be deliriously happy to score this well on a university genetics test—and it's this visceral understanding of the number that makes the comparison so effective.

But the initial impression generated by that clear image fails under closer examination and proves to be dramatically misleading. In this case, it's not the number that I dispute, but rather the effect of citing it. Here's the problem: there are something like 3 billion nucleotides in the human genome. A 1% difference that seems insignificant on a test becomes very significant indeed once you understand that it represents a difference of 30 million nucleotides. Of course, nucleotides aren't genes, so let's consider genes instead. Current estimates suggest that there are something on the order of 25 000 genes in the human genome, which means that the aforementioned 1% difference represents a difference of 250 genes between humans and chimps. Worse yet, a phenomenon known as alternative splicing means that each of those 250 genes may be responsible for the production of two, three, or more proteins that have important and sometimes even crucial regulatory effects on our bodies.

Clearly, there will be no hybrid chimp–human embryos anytime soon, despite that 99% similarity between us.

Another familiar example from evolution has been the anthropomorphism that organisms evolve to adapt to their environment. In fact, classical evolution tells us that organisms unable to adapt die before they can reproduce, and only those that can adapt to changes in their environment will survive to pass on their genes. It is the genes that survive through the generations and the species, not individual organisms, that evolve. Richard Dawkins famously captured this image in his book The Selfish Gene, which clearly and convincingly describes how genes seem to "selfishly" compete with each other for survival, sometimes at the expense of the organism's own goals and desires. Dawkins and his colleagues revolutionized the study of evolution by demonstrating the importance of this process.

Yet genes clearly have no consciousness, despite the implications of the word selfish. Forgetting this can mislead us into believing that all organisms are guided solely by their genes. While this may well be true for lower organisms, and is demonstrably true to some extent for even the highest organisms, this image can lead us to miss an important point: that humans may well be the first species on Earth that can think beyond the simple urging of our genes and make decisions (such as genetic engineering) that directly contradict the supposed urgings of our genes. Moreover, larger processes that are more difficult to quantify, such as social structures (e.g., religion, laws) and learned behaviors (e.g., the teaching of our parents), can exert behavioral influences every bit as powerful as those of our genes.

There are many other misleading word choices I encounter frequently. Consider, for example, the no artificial chemicals blazon on "organic" products. The word organic clearly communicates the fact that the product contains none of the really scary artificial (man-made) compounds that lead to the 300-word ingredient lists for even the simplest Kraft products. Yet none of us believes that "natural" chemicals such as arsenic, lead, cyanide, ergotamine, and digitalis are safe simply because they're natural. Similarly, there is much talk in agronomy about the merits of "organic" fertilizers versus "chemical" (inorganic) fertilizers—as if organic fertilizers are not, themselves, composed of chemicals. The simplicity of these and other wordings does make an important point clearly, but that's not good enough.

As scientific communicators, we must beware the temptation to simplify "facts" to the point that they become misleading. The high similarity between chimps and humans fails this test, and as a standard for comparison, it's tempting to propose (as I have done in the past) that it should be retired from our vocabulary. Similarly, those of us who must write about evolution and genetics learn to avoid oversimplifying evolution as either a process of conscious change by individuals or as malicious and selfish control by sentient genes. Those of us who write about chemistry must be careful to use precise terms such as inorganic or artificial rather than chemical and equally careful to use emotionally loaded words such as natural judiciously.

But there's a better solution than merely to avoid using simplistic wordings. Instead, I would propose an easy strategy for preserving the power of simplicity without sacrificing clarity: introduce concepts simply, but just as any good manuscript begins with an introduction and moves onwards to elaborate on that context, so must we build on that simple introduction and use it as a tool for delving deeper and revealing the true underlying complexity. That's a more challenging communications task, of course, but it's also much more satisfying when we succeed.


My essays on scientific communication have now been collected in the following book:

Hart, G. 2011. Exchanges: 10 years of essays on scientific communication. Diaskeuasis Publishing, Pointe-Claire, Que. Printed version, 242 p.; eBook in PDF format, 327 p.


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