Almost two years ago, I radically changed my diet. I gave up grains almost entirely and began eating a diet consisting of fatty meats, vegetables, and a little fruit, often referred to as a paleo diet. By any common measurement, my metabolic health improved tremendously, which I found pleasantly surprising after being obese for much of my life.
So when I logged into twitter on Sunday, I was amused to find Salon's review of a new book titled Paleofantasy: What Evolution Really Tells Us About Sex, Diet and How We Live, by evolutionary biologist Marlene Zuk. The book, according to Salon, demonstrates that the paleo diet is based on “misunderstandings about how evolution works and unfounded assumptions about how paleolithic humans lived.”
Usually my initial response to such assertions is to roll my eyes and go on my happy way not eating grains. But Zuk is an actual scientist, and she deserves to be taken seriously as a result. Nonetheless, her arguments, at least as they relate to diet and health, are complete nonsense, because we have a lot evidence which suggests that a paleo lifestyle is perfectly healthy.
The basis for the paleo lifestyle is fairly simple. Our evolutionary ancestors maintained certain dietary and exercise habits which enabled them to adapt to their very harsh environments and survive for well over 2 million years. Since we're not all that biologically different from them, we should embrace those same habits today.
Briefly summarized, Zuk's rebuttal is that evolution can proceed very rapidly, and thus humans can adapt to environmental changes, like different sources of food, relatively quickly. She also argues that at no point in our evolution were we perfectly adapted to our environment, so there is no need to live like our ancestors did.
When people change their lifestyles for the better, they usually aren't quiet about it, and this makes Zuk's thesis really easy to test. If she's correct, emulating our ancestors' dietary and exercise habits probably doesn't make us any healthier. But that's not what we find. We have evidence from thousands of people who have documented their experiences on a paleo diet, and the results are remarkable. People from all walks of life have lost weight, beaten eating disorders, reversed diabetes and heart disease — and all by living a lifestyle that Zuk says is “misguided nostalgia.”
If you're not inclined to believe internet testimonials, we can turn to the scientific literature, too. Research has shown that as America's consumption of grains and sugar increased, so did our propensity to get fat. Likewise, clinical trials investigating paleo and low-carbohydrate diets indicate that eliminating grains from the diet has the opposite effect.
Perhaps more importantly, since Zuk's argument is based on the rate of human evolution, study after study has found that it was our rapid transition away from paleo eating and into agriculture that led to the development of diseases like heart disease and diabetes. Or as a 2011 paper in Research Reports in Clinical Cardiology summed it up, “This mismatch between our ancient physiology and the western diet and lifestyle underlies many so-called diseases of civilization … which are rare or virtually absent in hunter–gatherers and other non-westernized populations.”
The reason Zuk gets this so wrong, I think, is that she places everybody who advocates a paleo lifestyle in the same category: A bunch of silly, rich people who foolishly long for a really harsh way of life. Of course, there are crazy people in the paleo camp, people who like to run barefoot or skip the grocery store to forage for greens outside their office buildings are good examples, but Zuk is generalizing a bit too much.
The point of going paleo has never been to “look to a mythical past utopia for clues to a way forward,” as she puts it. The point, quite simply, has always been to eat and exercise how we evolved to, but in our modern context. Nobody is suggesting we all go live in caves and eat only what we kill ourselves.