The Caveman Controversy
In her new book, Paleofantasy, Marlene Zuk dared to debunk a lifestyle that advocates eating, exercising, and even mating like our ancestors. Now the outspoken insect-sex researcher has adversaries, who say she’s the one whose thinking needs to evolve.
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As she became used to a new way of eating, the switch became permanent. Her typical breakfast might be eggs with sauerkraut and bacon. Lunch is salad or leftovers. And dinner consists of some kind of meat with vegetables, sometimes followed by berries or homemade coconut-milk ice cream. Kleppinger and her husband grow herbs and lettuce in a small garden and they compost kitchen scraps. Meat is so central to their diets that they recently bought a quarter of a cow through a share organized by a CrossFit coach and stocked their freezer with nearly 100 pounds of vacuum-sealed, grass-fed beef.
Like many people who join CrossFit and try the caveman diet, Kleppinger’s reasons for going Paleo aren’t necessarily evolution-related. “I don’t know if we’re designed to eat grains,” she says, digging into a lunch of rotisserie chicken, salad without cheese, and guacamole on chips—a small cheat since the chips are made from corn. “It’s less about trying to recreate a diet from so long ago than trying to stick as close to nature as possible,” she says. “What do you have to lose from cutting out processed food that comes out of a box, versus [eating] something that was raised locally? I always ask, ‘Would my great-grandmother recognize that?’ That’s a good way to describe this lifestyle.” (So is Kleppinger’s T-shirt, which displays phrases such as “farm-to-table,” “fair trade,” and “locally grown” clustered into the shape of Minnesota.)
Kleppinger’s goal is to be healthier, not necessarily to live like a cavewoman. After all, she doesn’t even like camping. And yet, at its root, the Paleo lifestyle is based on the belief that our modern lives are out of sync with our genes. On the website cavemanforum.com, Paleo proponents share recipes, workout journals, and tips for wild-food foraging. They also grapple with difficult questions: “Can a cookie really be Paleo?” Members also discuss parenting. One post, captioned “Cave girl in the making,” shows a preschool-age child eating a drumstick nearly as big as her head.
Cordain, who is based at the department of Health and Exercise Science at Colorado State University in Fort Collins, has published dozens of studies, both ethnographic and molecular, over the past several decades that illustrate how much healthier people are when they act as if they were living a long, long time ago. In a 2011 paper called “Exercise Like a Hunter-Gatherer: A Prescription for Organic Physical Fitness,” he explains that natural selection shaped our genes to fit a physically vigorous way of life. Because the bulk of our genes have remained the same for at least 40,000 years, many of today’s chronic diseases likely emerged from an inactive, indoor lifestyle. “Literally,” he writes in the Paleo Diet, “we are Stone Agers living in the Space Age.”
The same, Cordain argues, goes for food. In a 2002 study, he and colleagues analyzed the diets of 229 hunter-gatherer societies, which are often used as a proxy for people who lived eons ago. Though the details varied, results showed that animal foods made up about 65 percent of all of the diets. “If you look at the diets of wild animals, their genes have been hardwired by the selective pressures of their ecological niches, and their nutritional needs are hardwired into the genome,” Cordain says, intermittently fuming about Zuk and her lack of qualifications for criticizing his theories.
“Characteristics of the Western diet exceed by multiple standard deviations anything that our species ever consumed,” he says. “In a typical Western diet, we obtain 70 percent of our calories from refined sugar, refined grains, refined vegetable oils, and dairy. None of those foods existed until fairly recent times. When we talk about going back to the types of foods our ancestors ate, if you take those out of the diet, what’s left is real food: lean meats, fruits, vegetables, nuts, seeds, and living foods.”
Despite Zuk’s claims of dietary indifference, Paleo proponents are unhappy about a book that even hints that they might be living a fantasy. “I’ve spent the bulk of my career doing human research. I’ve co-authored papers with anthropologists and archaeologists and ethnologists, people who have been in the trenches with this data,” says Cordain. “I feel a little miffed that this person who is outside the field, who has never published a paper in this discipline, comes in and criticizes not just me but the entire discipline. I would never dream to critique insect biology. I would never dream to critique her papers. She is essentially uninformed.”