All the Little Live Things

If the world is made of magic, then maybe magic is made of microbes. After all, microbes are everywhere. They live in the oceans, in rocks, ice, and clouds. They predate us, they outnumber us, and they make up 90 percent of our body weight. They coexist with us, aid us, and hurt us in many mysterious and mostly invisible ways. Without them, we wouldn’t have enough oxygen to breathe. They help form our organs, they regulate our immune systems, and they might even determine how energetic or happy or calm we are. They can take over the DNA and hijack the basic functioning of insects and even mammals. The more you learn about them, the more you will get the unnerving sensation that microbes are not only omnipresent but also omnipotent. The world is formed and ruled by microbes, and we are merely their hapless puppets.

If that sounds like a shaky compound of exaggeration and understatement, much of it vague and grandiose and suspiciously unsubstantiated, well, then, welcome to the world of popular-science writing. Arguably the best (and also maybe the worst) science writers are an odd combination of poet, storyteller, curbside clairvoyant, and absent-minded professor whose lectures sound like badly translated dispatches from a planet light-years away. For proof, look no further than the titles of two new microbe-themed books: I Contain Multitudes: The Microbes Within Us and a Grander View of Life (Ecco, $28), by Ed Yong, and This Is Your Brain on Parasites: How Tiny Creatures Manipulate Our Behavior and Shape Society (Eamon Dolan/Houghton Mifflin Harcourt, $27), by Kathleen McAuliffe. If you’ve ever doubted the power of microbes to shape society and offer us a grander view of life, read on and find yourself duly impressed. Just don’t be surprised if it’s sometimes hard to see the microbiome for the microbes.

Yong, a science writer at The Atlantic and blogger for National Geographic’s Phenomena, brings a lot of creative flair and wit to every corner of the microbial world. On page after page, he’s more than happy to stretch the dry boundaries of science reporting with poetic ruminations, mixed metaphors, and a delighted fanboy outlook. Take Yong’s passion for “microbe-given superpowers” that can turn some animals into “evolutionary winners, which can digest indigestible foods, withstand inhospitable places, survive fatal meals.” (Sounds like these critters are ready for a visit to Disneyland.) Or witness Yong’s gushing enthusiasm for—what else?—certain strains of bacteria. “It is not unusual for science writers who regularly write about microbiology to pick a favorite bacterium, much as people would choose a favorite film or band. Wolbachia is mine.” Marvel at Yong’s recasting of the common, inaccurate view of the immune system as “an armada of destructive troops, belligerently bent on destroying microbes”: “I think it’s more accurate to see the immune system as a team of rangers in charge of a national park—as ecosystem managers.” Whether he’s describing the glut of potential pathogens that live in hospitals or describing trends in fecal-matter transplants (“Inspirational and instructional videos have appeared online, as have large communities of DIY-transplanters—eager groups of people who truly, literally, give a shit”), Yong approaches every inquiry with curiosity and humor.

In keeping with such imaginative flourishes, Yong follows his whims wherever they lead, but this sometimes means zooming into the minute details of a specific species of bacteria when the big picture or greater significance of the example isn’t entirely clear—or burrowing into a case study, then leaving it behind just as things are starting to get interesting. Yong favors a kind of professorial, “You’ll catch up eventually!” approach; he will introduce dozens of examples of microbial phenomena without clearly outlining their significance, and dive into abstract minutiae in order to uncover new dimensions of a problem that’s never been spelled out, searching for answers to mysteries the reader doesn’t fully understand yet. For several pages, Yong investigates the case of a microbial symbiont (a microbe that coexists with its host instead of hurting it) that has evolved within the thirteen-year cicada. The bacterium, a descendant of Hodgkinia, somehow split into countless varieties, “its DNA eventually assembled into at least 17 distinct rings, and maybe as many as 50.”

These numbers might be impressive and interesting if we had any idea how DNA assembles into rings in the first place—and if so, how many, typically; and if this is normal or insane; and why these things matter or relate to the peculiarities of bugs that live underground for thirteen years at a time. Yong likes numbers and details but doesn’t always like to slow down to contextualize them. Similarly, he likes examples but doesn’t always manage to paint the larger picture that shows why they’re important. He does assert that if the symbionts continue to break into smaller pieces (and what does that mean exactly?), then the thirteen-year cicada itself may become extinct.

A scanning electron micrograph image of Streptococcus bacteria. Niaid/Flickr

The central point here is that sometimes even “helpful” microbes can “go rogue” and doom their hosts. But when you combine that insight with the gaps in Yong’s explanatory skills, the absence of any real why-does-this-matter background (especially useful here since, without it, readers are left thinking this particular strain of bacteria may doom what’s essentially a plague of locusts), and the very basic narrative challenge of all this microbial stuff’s being, by definition, very small and pretty abstract and hard to grasp, it adds up to a shrug of indifference. Popular-science books designed for educated nonscientist readers can’t inspire awe and wonder without also offering reliably clear, concise explanations and inspiring portraits of how the intricate components of their corner of the cosmos actually fit together.

Thankfully, we have Kathleen McAuliffe for that. To borrow the terminology of the scientific method, where Yong is all about gathering and examining as much data as possible without drawing clear conclusions, McAuliffe is an inventive (and entertaining) creator of fantastical hypotheses that hint at downright epic (but sometimes unsubstantiated) conclusions. McAuliffe’s 2012 article on toxoplasmosis, “How Your Cat Is Making You Crazy,” also published in The Atlantic (a redoubtable source of scarifying popular-science explainers, it seems), won so much viral attention that it might as well have been titled “21 Cats That Are Totally Making Us Crazy Right Now.” And because agents and publishers are a little bit like the enormous number of helpful microbes in your gut, aiding in the digestion of every wildly popular article and then quickly breaking it down into book-contract dollars, McAuliffe now offers us an entire book filled with tales of wily parasites (and their hosts) gone awry. But while Yong’s microbial survey is much more representative of the kind of inspired but haphazard book that springs from online popularity, McAuliffe is that rare writer who’s able to distill complicated subjects without losing nuanced distinctions along the way. From start to finish, she spins a consistently engrossing tale of invasive creatures that can alter your behavior and outlook, depress your cognitive functioning, and even make you more violent or sexually aggressive.

Where Yong gets tripped up by a layman’s assumptions about “bad” and “good” microbes, revealing a series of contradictions, McAuliffe tackles the big picture in one fell swoop without oversimplifying: “A number of strains labeled pathogens . . . actually inhabit us all the time, causing trouble only when we’re run-down or when unusual conditions favor their growth. The same species of bacteria may be a helper (a symbiont), a harmless freeloader (a commensal), or a hurter (a parasite), depending on circumstances that are constantly in flux.” McAuliffe is arguably less of a rabid, micro-level enthusiast than Yong; she’s attracted to broader, more sensational topics and more heterodox and unconventional personalities in the scientific community. Even so, she’s never one to conflate correlation and causation, or to present unsubstantiated theories as if they were thoroughly supported by evidence.

But that doesn’t mean she’ll sidestep a compelling story. In the second half of her book, McAuliffe’s interest in toxoplasmosis and rabies yields to a more sociological inquiry into the wider applications of “parasite stress”—anxious behaviors animals and humans engage in when they sense a chance of infectious entities in their environment. Some researchers have suggested that racism and xenophobia might ultimately be linked to biological suspicions that foreigners may be bringing pathogens from afar. And indeed, several studies linked sensitivity and germophobia to conservatism and a distrust of unfamiliar individuals. Based on these findings, researchers guessed that in areas where parasite stress is highest, they would find more conservative governments and greater distrust of outsiders. They did; and moreover, “countries under severe parasite stress were more likely to be controlled by dictators; gender inequality was pronounced, and wealth tended to be concentrated in the hands of a small class of elites.” While a researcher McAuliffe quotes admits that such studies might be viewed as “horribly self-serving”—more declarations from the Western world that the Western world is more sophisticated than its neighbors—the data seem to back it up. This is the sort of correlative research many scientists wouldn’t touch with a ten-foot thermal cycler, but it’s hard to resist the pull of such intuitive theses. After all, isn’t Donald Trump a notorious germophobe?

In short, McAuliffe’s book reflects both the promise and the danger of compelling narration. When a writer is extremely persuasive, it’s hard not to get carried away. McAuliffe herself admits to this weakness by the end of the book. “Maybe we ourselves are organisms inside some cosmic superbeast,” she gushes. On the other hand, maybe she’s just losing it. “My mind is exploding with thoughts of parasites. For all I know, they may even be ensconced in my brain, quietly nibbling away at my sanity.” Whether you follow Yong’s rigorous but repetitive uphill switchbacks or tumble with McAuliffe down a magical rabbit hole, this is where you will land: stunned and bewildered by the terrifying and elusive world thriving around us and inside of us, binding the galaxy together. Luminous beings are we—if by “we” you mean the 10 percent made up of human cells and the 90 percent that’s an ever-changing, teeming microbial universe of “other.” This “grander view of life” we were promised is truly wonderful, and also horrifying. Then again, maybe that’s just my microbes talking.

Heather Havrilesky is a columnist for New York magazine and the author of How to Be a Person in the World (Doubleday, 2016).