03.21.13

Eat Like a Caveman? The Trouble With Paleo Living

Should we live like our hunter-gatherer forebears, run barefoot and eat nothing but meat, nuts, and fruit? Robert Herritt says a new book shows that paleo living is based on a misreading of evolution.

What is it about nostalgia that so effectively scrambles our evaluative faculties? You hardly need to consult Proust to experience this innately human tendency to long for previous times and places probably best left unlonged for: postwar suburbs, high school, the ’90s.

Thinking fondly of some gauze-filtered yesteryear where manufacturing jobs abounded and kids played outside more is one thing. But proponents of the so-called paleo lifestyle are taking it back a bit further—all the way to the Pleistocene. This popular movement advocates for a return to some of the habits of our pre-agricultural relatives when it comes to eating, exercising, or even rearing children.

The reasoning deployed by such aspiring cavemen goes something like this: since humans evolved in an environment far different from the one we currently inhabit, the road to health and happiness lies in adopting a few of the practices of our hunter-gatherer forbears.

In other words, some paleo proponents have it, we’ve evolved to eat meat, nuts, and fruit, not grains and dairy. And our bodies are better suited to irregular bursts of predator-evading or prey-tracking activities, not daily, long-distance jogs in designer running shoes. What’s more, many of our most common health problems have arisen because of our unfortunate deviation from such prelapsarian modes of action.

Among the most prominent defenders of this view is Loren Cordain, a professor at Colorado State University’s health and exercise science department. He and his fellow researchers have argued that hunter-gatherers rarely or never suffer from coronary heart disease, obesity, hypertension, type 2 diabetes, epithelial cell cancers, autoimmune disease, and osteoporosis—“diseases of civilization.” It is the “mismatch” between our ancient bodies and the modern diet and lifestyle that brings about these problems.

There is a certain parsimony to this view, but it is also the kind of back-of-the-napkin evolutionary theorizing that begs to be cut down by a thoughtful specialist. Marlene Zuk is happy to oblige in her new book Paleofantasy: What Evolution Really Tells Us About Sex, Diet, and How We Live. Zuk, who is a professor of ecology, evolution, and behavior at the University of Minnesota, brings the right mixture of expertise and humor to the task.

She argues that the line of thinking that animates much of paleo living begins with some questionable premises. “The notion that humans got to a point in evolutionary history where their bodies were somehow in sync with the environment … reflects a misunderstanding of evolution,” Zuk writes. “What we are able to eat and thrive on depends on our more than 30 million years of history as primates, not on a single, arbitrarily more recent moment in time”—that is, not merely on some hunter-gatherer fantasy.

The work of using evolutionary logic to explain human traits is more like multivariable calculus than simple arithmetic.

Just like all other organisms, the process of evolution by natural selection has left humans full of “good enough” features that have never been perfectly fitted to the world around us. In one example, Zuk notes that hiccups, hernias, and hemorrhoids are all caused by “an imperfect transfer of anatomical technology from our fish ancestors.”

Attempts to mimic the eating habits of our foraging relatives results from a confused understanding of our history. According to Zuk, humans ate different foods in different places, and “thrived on the variety.”

Perhaps the biggest paleo-fallacy identified by Zuk is the assumption that our biology has somehow stopped changing since the dawn of agriculture. She notes that there’s “a strong body of evidence” that our genome has changed as we spread across the world and discovered farming, “making it difficult at best to point to a single way of eating to which we were, and remain, best suited.”

The same goes for claims about caveman-inspired exercise regimens and child-care philosophies.

Granted, Zuk doesn’t deny that an understanding of evolution can provide important insights into human behavior and health. But as this informative book demonstrates, the work of using evolutionary logic to explain human traits is more like multivariable calculus than simple arithmetic.

This is on display in a chapter exploring the complex interactions between genes and culture that gave us our fairly recent ability to digest lactose into adulthood. The process is so complex that understanding it requires the use of everything from computer modeling to the analysis of buttermilk particles recovered from thousand-year-old ceramic vessels.

Even if Zuk is right on the science, her book is unlikely to send practicing paleos running for the cereal aisle. As with so many other lifestyle doctrines, paleo living could be seen not merely as a matter of science or health, but as a way of declaring oneself a member of an enlightened group. Sure, there’s a strange Stone Age nostalgia involved, but for some, adopting a paleo-diet or a caveman fitness routine might be a way to flaunt one’s secular humanism—part science-inspired philosophy of health, part Darwin-fish bumper sticker.