"The first thing you have to do to study 4,000-year-old DNA is take off your clothes." Marlene Zuk's new book Paleofantasy: What Evolution Really Tells Us About Sex, Diet, and How We Live begins in classic science-writer style. This provocative line pulls the reader into a world where Science Happens, but in a way that isn't intimidating. Like Robert Krulwich of Radiolab fame, Zuk appears to be along for the ride, experiencing this DNA analysis for the first time. It may be a well-worn writing tool, but it serves Zuk beautifully as she then transitions from guide-to-the-side to sage-onstage for the rest of the book. Zuk's explanations of evolutionary theory, natural selection, and genetic variation are relatable and powerful. I will be assigning passages of this book to my students for many years to come.
The purpose of this book, of course, is not to provide a mere evolutionary theory explainer. Instead, Zuk wants to take on the false beliefs that have permeated popular culture about the impact our evolutionary history has had on our bodies, decisions, and lives. Zuk charges laypeople and sometimes scientists with having an incorrect account of how ancestral humans really lived, borrowing renowned anthropologist Leslie Aiello's term "paleofantasy." Why does this matter? According to Zuk, it's not just that the paleofantasies we construct of long-distance-running, spear-throwing, meat-eating men (always men) are historically inaccurate, but also that such fantasies are then applied to modern life in ways that are deeply flawed—as if a manufacturer of mattresses decided to base their construction on the story of The Princess and the Pea.
Zuk's strongest exhibit for the problem of paleofantasy is the Paleo Diet, frequently interpreted as one containing lots of meat and eschewing grains, legumes, and sugars. The Paleo Diet has been a favorite dumping ground of many critical writers and researchers lately, for good reason: the anthropologists who study ancestral diets have always said that there is no one ancestral diet, but rather that diet is a result of a complex interplay between climate, available food sources, and human culture and technologies. Zuk demonstrates a lower ancestral incidence of meat-eating than the Paleo Diet assumes; she adds that agriculture—which, according to many Paleo Diet proponents, was a horrid innovation—began not the oft-cited 10,000 years ago but at least 30,000 years ago. And the biggest misunderstanding of evolutionary history she corrects, one which might turn all paleofantasies to dust, is the mismatch theory: the idea that we haven't evolved appreciably since the Pleistocene and thus have bodies mismatched to our modern environments.
There was one way in which I struggled with Paleofantasy. Zuk uses comments from blog posts, paleo diet forums, and news stories to represent the way laypeople construct paleofantasies. The blogosphere circles I move in work from the premise that blog comments represent the loudest—and thus also the most radical—voices, rather than majority opinion. To represent scientists, Zuk either visits and interviews them directly, as in the introduction, or uses their best work: peer-reviewed, published journal articles. This seems vastly unfair to me, creating a straw layperson who claims that the perfect combination of Crossfit exercise, standing desks, wild-caught meat, polygynous mating, and infant co-sleeping will cure cancer. Naturally, the views of this credulous layperson are easily demolished by Zuk's well-explained inventory of PhD-level research.
But what would have happened if Zuk had also spent some time identifying the motivations or reasons that underlie a paleofantasy approach to health—mistrust of modern medicine, poor educational background in science, or science communication breakdowns? In that case, portions of the book would have felt less like a reproach and more like encouragement to delight in evolution the way she does. The un-interviewed layfolk who think they should live like their ancestors are like the dead crickets who cannot sing, an anecdote from the author's own research on a cricket population that stops making mating calls over a few short generations to avoid the attention of a deadly parasite. They are shut down before given a chance to explain themselves.
That said, overall Paleofantasy succeeds at being a patient, brilliant, and eager guide through the contradictory and complicated web of scientific evidence on human evolution and health. This book really does serve as a bridge between popular understandings of evolution and modern interpretations of scientific evidence, and Zuk's marvelous style kept me engaged to the end. Her admonishments are (mostly) gentle enough and her explanations so elegant that I would recommend passing this book along even to the friend who wears Vibram Five Fingers to dinner parties. He won't stop wearing them, but he might stop pushing you to eat an extra serving of turkey over stuffing at Thanksgiving.
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This review originally appeared in Science in Focus.