In 2014, chemist Floyd Romesberg, of the Scripps Research Institute, synthesized a new pair of artificial nucleotides and got a cell to accept them as part of its genetic code. In metaphorical terms, he extended the alphabet of life.

To review, the DNA molecule is built from four nucleotides, or “letters”: adenine (A), thymine (T), guanine (G) and cytosine (C). Each letter is one half of a pair—A always goes with T, and G with C—and each pair forms a single rung of the molecule’s twisted ladder. Romesberg’s team, after years of work, synthesized a third pair—X and Y—and inserted it successfully into the code of a bacterium, which then reproduced, maintaining its synthetic code. Life on Earth depends on a four-letter code; Romesberg had invented a life-form with six. In 2017 he updated the accomplishment, optimizing and stabilizing the cell. More important, he showed that the cell could express a novel protein. “We stored information, and now we retrieved it,” Romesberg told The MIT Technology Review. “The next thing is to use it. We are going to do things no one else can.”

Discussing his project with The New York Times in 2014, Romesberg used a metaphor: “If you have a language that has a certain number of letters,” he said, “you want to add letters so you can write more words and tell more stories.” In his TED Talk, he extended this metaphor, asking the audience to imagine a typewriter with only four keys. Wouldn’t six keys be better? Couldn’t you say more? The metaphor seems flawed to me. It may be that new nucleotides = new amino acids = new organisms, but it does not follow that new letters = new words = new stories. I know lots of writers, but none of us have been thinking, “If only there were 30 letters in the alphabet, then I could finish my novel, The Story of Jimβθ!”

George Estreich is the author of The Shape of the Eye: A Memoir. His writing has appeared in Tin House, The New York Times, Salon, and other publications. The MIT Press

Romesberg is careful to separate himself from wings-and-ultraviolet-vision transhumanism. His declared goals are squarely, soberly medical: A six-letter alphabet could code for a larger complement of possible amino acids, which could be assembled into proteins not found in nature, which might be useful as medicines, which Synthorx, the company Romesberg cofounded, hopes to develop for profit. And yet Romesberg’s metaphor points to a tension between expansive and restrictive views of technology. On the one hand, to “tell more stories” can be glossed as “creating as many novel life-forms as possible.” On the other hand, Romesberg defined those “stories” in familiar, clinical terms—curing disease, including cancer—and the cells, Romesberg noted, would remain obediently in the lab, dependent on a diet of artificial nucleotides to stay alive. Their meaning would be circumscribed, contained, their lives kept safely in vitro. Romesberg’s rhetoric walks a familiar line between old and new, “natural” and “synthetic.” In this, it mimics the application it serves, which splices old and new nucleotides, natural and artificial, together. But more significant is the fact that Romesberg uses metaphor at all---that he uses literary techniques to persuade and does so self-consciously, reflecting on the materials of meaning. He behaves as, is, a writer.

For high-profile scientists, the ones who speak to lay audiences, write popular books, and deliver TED Talks, metaphor is a key persuasive tool. The right metaphor can soothe fears, explain the recondite, and familiarize the unfamiliar. It is scary to say, “We want to create, not only new life, but a new kind of life, one fundamentally different from every single organism that has ever lived.” It’s less scary if creating new life-forms is just like telling stories. We associate stories with entertainment, meaning, and self-expression. Like the vaguely positive keywords anchoring ads for noninvasive prenatal testing ( health, choice, empowerment) or de-extinction (revive, restore), story shines a rosy, apolitical light on a technological development, familiarizing the new.