Jellyfish Age Backwards

"Jellyfish Age Backwards

By Nicklas Brendborg

(Little, Brown, 268 pages, $29)

When Benjamin Franklin wrote that "nothing can be said to be certain, except death and taxes," he must have thought he was stating an eternal truth. But if biotechnology researcher Nicklas Brendborg is to be believed, Franklin's joke may need some updating. According to Mr. Brendborg, scientists have discovered a jellyfish the size of a fingernail that responds to stress by "ageing backwards," reversing the normal direction of its development to become a bottom-dwelling polyp. This trick can be repeated over and over again with "no physiological recollection of having been older," he explains, making this jellyfish "an example of the holy grail of ageing research -- biological immortality."

This tiny Methuselah is one of the striking examples in Mr. Brendborg's breezy survey of the science of longevity, "Jellyfish Age Backwards," which the author has translated from the Danish with Elizabeth DeNoma. It takes its place alongside the immunosuppressant rapamycin, the ancient practice of fasting, and the humble garlic clove as a leading light in the quest "to 'die young' as late as possible."

Mr. Brendborg begins with the natural world, introducing us to a 390-year-old shark, a giant network of trees that has grown for more than 14,000 years, and a creature bucking the trend that bigger animals tend to live longer: the naked mole-rat. This bald, pink rodent from East Africa is about the size of a mouse but lives well over 30 years. Mr. Brendborg gives an insight into the practicalities of biological science when he describes these remarkable creatures from the researcher's perspective: "Long-lived? Check. Can be kept in a laboratory? Check. A mammal like us? Check. So far, so good." The naked mole-rat is also a close relative of both the mouse and the rat -- two animals that are both widely studied and have much shorter lifespans -- opening up a broad range of comparative studies.

Turning next to our own species, Mr. Brendborg tackles genetics, with an admirably clear sketch of heritability and how our longevity is determined by both genes and the environment. He arrives at the conclusion that "your lifespan is not very genetically determined at all . . . good news if you want to do something about how long you're going to live." And even this small effect can be countered, Mr. Brendborg argues. Genes are, after all, "neither magic nor fate. They're just the recipes for proteins . . . If we learn how genetics shape differences between people, we can find ways to mimic the effect using drugs or technology."

This optimistic inference places a lot of weight on that "if," particularly since researchers still don't know what aging really is. Some argue that we age because our systems for ongoing repair are inevitably imperfect, and Mr. Brendborg outlines why it's hard for natural selection to weed out genes that cause problems only after organisms have reproduced. But others suggest that physiological decline is part of the developmental processes that enable us to mature, a theory that raises the possibility that -- as in the case of the jellyfish -- these processes could simply be rewound.

Since life developed in adversity, life has evolved mechanisms to cope with it, which explains why exercise is good for you despite being so awful while you're doing it. Mr. Brendborg charts how studies of antioxidants, arsenic and even radiation demonstrate the principle of hormesis: What doesn't kill you makes you stronger. But he cautions against exposing yourself to radioactivity or eating poison: "We have no idea what levels could potentially be hormetic but we do know what happens if you exceed those levels: pain and a horrible death."

The warnings against self-experimentation continue while Mr. Brendborg considers discoveries at a cellular level. As communities of 37 trillion cells, we depend on each cell cleaning up the byproducts of its operations and taking itself out of action if something goes wrong. Mr. Brendborg introduces a series of microscopic components, from the mitochondria that play a central role in metabolism to the telomeres that stop chromosomes fraying, and an array of compounds that influence their workings such as spermidine, telomerase and rapamycin.

With no wonder drug as yet identified, Mr. Brendborg moves on to a level-headed discussion of lifestyle. Rodents reared with fewer calories live 20% to 40% longer, which sounds promising until he adds that human volunteers following a similar regime feel cold, sluggish and tired. (It's not yet clear whether calorie restriction will extend our life, he continues, "but it will certainly make it seem like life is very long.") Mr. Brendborg is skeptical about much nutrition science, highlighting problems with studies funded by food companies, which "to everyone's surprise . . . often yield results that are beneficial to their donors," and with confounding factors such as wealth, which perhaps skew surveys on habits such as veganism or drinking red wine. But his advice -- eat your greens (with garlic), floss your teeth and do some exercise -- is delivered with good humor and realism.

Short chapters built from short, declarative sentences combine with familiar material to give "Jellyfish Age Backwards" the feel of an introductory survey rather than a novel argument. Perhaps its piecewise construction is only a reflection of the disjointed state of the subject, where researchers are pulling on various threads but have not yet managed to knit them into a coherent whole. Mr. Brendborg finishes with a ringing declaration that the "noble" efforts of medical science will "eventually defeat" aging. But biology is complicated, as the author admits, and the strands of this multivariate and complex phenomenon may eventually prove to be tangled in some unresolvable knot. It seems that Franklin's quip can look forward to a long and vigorous old age.” [1]

1. Dying Young At a Late Age
Lea, Richard.  Wall Street Journal, Eastern edition; New York, N.Y. [New York, N.Y]. 30 Dec 2022: A.15.