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.
Michael Jacobsen (Illustration)
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Tucked in the back of a concrete industrial building, the workout space is mostly bare: the exercise equipment consists of a cage-like network of pull-up bars, some gymnastic rings, racks of weight plates and medicine balls, and a few stationary bikes lining one wall. During hour-long classes, metal-punk music blares as a coach guides clients through a dynamic series of exercises, ranging from the familiar (jumping rope) to the slightly convoluted (a combination pushup-handstand maneuver against a wall). As fitness routines go, it’s pretty hardcore.
For some CrossFit enthusiasts, the studio is simply a place to get a good workout. For others, CrossFit quickly becomes part of a lifestyle that evokes a time, tens of thousands of years ago, when our ancestors stayed fit and strong simply by living in a self-sufficient manner, hunting and gathering all of their food. And at some point, many CrossFit members experiment with eating Paleo.
Also known as the caveman diet, Paleo eating emphasizes meat, fruits, and vegetables while excluding grains, legumes, dairy, and added sugars. In terms of meal planning, it’s more well-rounded than the baby-food or grapefruit diets but stricter than Weight Watchers or South Beach. Though the media stereotype of a so-called “ancestral health” participant is a young, male gym rat with a serious carnivorous streak, recent studies show that most Paleo proponents are actually middle-aged women motivated by weight loss and health concerns.
The fundamental philosophy, according to evolutionary nutritionist Loren Cordain, author of the Paleo Diet: Lose Weight and Get Healthy by Eating the Foods You Were Designed to Eat and a related empire of books, is that our processed-food-filled modern diets have strayed far from what our pre-agricultural, hunter-gatherer genes were fine-tuned to use as fuel during the Paleolithic period. The result: diabetes, heart disease, and all sorts of other modern health woes. If we did what our bodies were meant to do, in terms of diet and exercise, Cordain argues, we would be healthier.
A few years ago, Cordain was at an evolutionary-medicine conference talking about a grim-sounding condition called leaky gut syndrome. Digestive difficulties occur, he explained, when people with a particular form of an immune-system gene eat any one of a number of foods commonly found in modern diets—bread, potatoes, and root beer among them.
At least one of the conference attendees was skeptical. Marlene Zuk, a trim, middle-aged evolutionary biologist who studies, among other things, the sex lives of crickets, raised her hand.
Why, the insect researcher asked the nutritionist, did he think this gene form still existed when it was so disadvantageous? Shouldn’t natural selection have eliminated it from the human population by now? “There hasn’t been enough time,” Cordain answered. Zuk, who is now based at the University of Minnesota, pressed him to explain. He responded that people started eating these foods only after the agricultural revolution 10,000 years ago, and that genes couldn’t change that quickly. “Plenty of time,” Zuk challenged. Cordain protested. She repeated herself.