This is your brain on parasites How tiny creatures manipulate our behavior and shape society

Science journalist McAuliffe takes an "unabashedly parasite-centric view of the world" to suggest that perhaps microorganisms are actually the ones in control of human lives, with parasitic manipulation guiding human behavior and thoughts. Noting that correlation does not equal causation, McAuliffe reports on provocative studies that link contagious vectors-such as the feline-associated, behavior-changing Toxoplasma gondii, which was the subject of her virally popular article in the Atlantic-to mental illness and libido fluctuations, and others that link organisms thought of as symbionts, such as human gut bacteria, to obesity and personality. McAuliffe also presents some well-established yet still astonishing facts about neuroparasitology. The hairworm, for example, makes crickets behave erratically and head for water, leaving them easy prey, while the Ophiocordyceps fungus turns carpenter ants into "zombie ants." But by the book's end, she careens wildly toward biological determinism regarding a "behavioral immune system" that causes humans to shun the abnormal and unknown. She addresses studies linking visceral experiences of physical disgust with xenophobia and moral conservatism, and others that have connected living in an area prone to disease with developing a collectivist culture. McAuliffe presents her collected research-often from small, nearly anecdotal studies-less as fact than in a spirit of exploration. Agent: Zoë Pagnamenta, Zoë Pagnamenta Agency. (June) © Copyright PWxyz, LLC. All rights reserved.

1: Before Parasites Were Cool   It's not easy being a parasite. Sure, you get a free meal. But the life of a moocher still comes with plenty of stresses. You have to be able to adapt to the environment inside one, two, or, if you belong to a class of parasitic worms known as trematodes, three different hosts âe<-- âe       The answer to that question is what set Janice Moore on her life's path. In 1971, she was a senior at Rice University in Houston sitting in an introductory course on parasitology taught by a titan in the field, Clark Read, a lanky man with a commanding presence and an odd style of lecturing. He would puff away on a cigarette and seemingly free-associate, drawing students into his passion with fascinating details about different species of parasites that he presented with no discernible regard for logic or order. But he was a gifted storyteller who could evoke the lives of parasites so richly that you could almost picture what it was like to be one. He also knew how to spin a good mystery, which was how he ensnared Moore.        She couldn't imagine how to get an ant into a sheep's mouth in spite of Read's admonishment to "think like a trematode!" In fact, no one could, because the solution the parasite lit upon is absurdly improbable: It invades a region of the ant's brain that controls its locomotion and mouthparts. During the day, the infected insect behaves no differently than any other ant. But at night, it does not return to its colony; instead, it climbs to the top of a blade of grass and clamps onto it with its mandibles. There, it dangles in the air, waiting for a grazing sheep to come by and eat it. If that doesn't happen by the next morning, however, it returns to its colony.        Why doesn't it just stay attached to the leaf? asked Read, scanning the classroom as if he expected his students to discern the trematode's logic. Because otherwise, he told his rapt audience, the ant will fry to death in the noonday sun âe<-- âe       Read's tale stunned Moore. The trematode called to mind a comic-book arch villain who controls minds with a joystick, causing law-abiding citizens to rob banks and commit other crimes so the villain can take over the world. The report of the trematode's astonishing feat came from a German study done in the 1950s, but, thrilling Moore, Read had just learned of research being done on a different organism that was producing findings similar to the Germans'.        The protagonist of this tale was a thorny-headed worm âe<-- âe