Paleo Fantasy

I’ve often wondered about the Paleo diet, hearing both good and bad about it. Considering we’re dealing with a post-heart attack person who is doing fabulously on a plant based plan, I’ve just watched the brouhaha without comment. Also, considering the Paleo diet is in direct opposition to the American Heart Association plan… well I’m slow to take chances on a probably-fad diet.

So, when I found Marlene Zuk’s book, PaleoFantasy: What Evolution Really Tells Us Aout Sex, Diet, and How We Live, my interest piqued. She’s got quite the credentials.

Four years ago, biology professor Marlene Zuk was attending a conference on evolution and diseases of modern environments. She sat in on a presentation by Loren Cordain, author of “The Paleo Diet” and a leading guru of the current craze for emulating the lifestyles of our Stone-Age ancestors. Cordain pronounced several foods (bread, rice, potatoes) to be the cause of a fatal condition in people carrying certain genes. Intrigued, Zuk stood up and asked Cordain why this genetic inability to digest so many common foods had persisted. “Surely it would have been selected out of the population,” she suggested.

Cordain, who has a Ph.D in exercise physiology, assured Zuk that human beings had not had time to adapt to foods that only became staples with the advent of agriculture. “It’s only been ten thousand years,” he explained. Zuk’s response: “Plenty of time.” He looked at her blankly, and she repeated: “Plenty of time.” Zuk goes on to write, “we never resolved our disagreement.”

The author of this article calls PaleoFantasy a:

…a conclusive refutation of Cordain’s quixotic, if widespread, view of human evolution, along with many other misconceptions. Zuk — who has a puckish humor (she describes one puffy-lipped Nicaraguan fish as “the Angelina Jolie of cichlids”) and a history of studying evolution, ecology and behavior — found herself bemused by how the object of her research has been portrayed in various media and subcultures. She cruised the New York Times’ health blog and sites like cavemanforum.com, collecting half-baked interpretations of evolutionary “facts” and eccentric theories ranging from the repudiation of eyeglasses to the belief that carbs can make one’s nose “more round.”

Interesting, eh?

Although she writes, “I would not dream of denying the evolutionary heritage present in our bodies,” Zuk briskly dismisses as simply “wrong” many common notions about that heritage. These errors fall into two large categories: misunderstandings about how evolution works and unfounded assumptions about how paleolithic humans lived. The first area is her speciality, and “Paleofantasy” offers a lively, lucid illustration of the intricacies of this all-important natural process. When it comes to the latter category, the anthropological aspect of the problem, Zuk treads more gingerly. Not only is this not her own field, but, as she observes, it is “ground often marked by acrimony and rancor” among the specialists themselves.

Here’s what I found particularly interesting:

Zuk detects an unspoken, barely formed assumption that humanity essentially stopped evolving in the Stone Age and that our bodies are “stuck” in a state that was perfectly adapted to survive in the paleolithic environment. Sometimes you hear that the intervention of “culture” has halted the process of natural selection. This, “Paleofantasy” points out, flies in the face of facts. Living things are always and continuously in the process of adapting to the changing conditions of their environment, and the emergence of lactase persistence indicates that culture (in this case, the practice of keeping livestock for meat and hides) simply becomes another one of those conditions.

For this reason, generalizations about the typical hunter-gatherer lifestyle are spurious; it doesn’t exist. With respect to what people ate (especially how much meat), the only safe assumption was “whatever they could get,” something that to this day varies greatly depending on where they live. Recently, researchers discovered evidence that people in Europe were grinding and cooking grain (a paleo-diet bugaboo) as far back as 30,000 years ago, even if they weren’t actually cultivating it. “A strong body of evidence,” Zuk writes, “points to many changes in our genome since humans spread across the planet and developed agriculture, making it difficult at best to point to a single way of eating to which we were, and remain, best suited.”

I particularly like the conclusion:

Why are we so intent on establishing how paleolithic people ate, exercised, coupled up and raised their kids? That’s a question Zuk considers only in passing, but she hits the nail pretty solidly on the head: “We have a regrettable tendency to see what we want to see and rationalize what we already want to do. That often means that if we can think of a way in which a behavior, whether it is eating junk food or having an affair, might have been beneficial in an ancestral environment, we feel vindicated, or at least justified.” Even if we wanted to live like cavemen, Zuk points out (noting that the desire to do so somehow never seems to extend to moving into mud huts), we couldn’t. In reality, we don’t have their bodies, and don’t live in their world. Even the animals and plants we eat have changed beyond recognition from their paleolithic ancestors. It turns out we’re stuck being us.

I’ll purchase this book and will let you know what I think of it.

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  • Eric

    Based on the article, I think Zuk has an axe to grind. Her two primary arguments in the article are of the straw man variety…

    First, sure, evolutionary adaptations can happen in as short as 10,000 years, but lactase persistence doesn’t make it optimal to drink milk — it just means that at some point in time, the mutation (which was a minor one — it only required flipping two genes, and didn’t change our physiology at all) helped some people survive under some conditions at some time long enough for the mutation to spread. You can imagine if there are food shortages but you’ve got milk-producing cows that lactase persistence might be beneficial for survival.

    Her other argument seems to be that “blind caveman re-enactment” is silly and unscientific. You wouldn’t know it based on how some paleo products are marketed and how some people act on internet forums, but the movement is hardly based on ideas like this… Rather that we should use evolutionary biology as a framework for generating hypotheses, like we do in every other biological science. It’s widely recognized among the paleo movement that there isn’t enough scientific data to fully validate a lot of the recommendations being made, and there are definitely assumptions being made to fill in the gaps. But it’s not blind re-enactment or fantasy. There have been a small handful of studies on the paleo diet with small sample sizes, but not enough. The goal of the movement is to use science as best we can, but fill in the gaps with a framework that makes sense, until there’s more science available.

    I hope Zuk decides to include actual references in the book, which the article was sorely lacking.

    I think in general you’d find that paleo and vegetarians have more in common than they don’t. Plants make up a huge portion of the paleo diet, and by some measurements, more than in a vegetarian diet. Rather than taking sides and writing books like Paleofantasy, we should all be scrutinizing the research and working towards a common goal.

    • Hi Eric,

      Thanks for your thoughtful comment. Considering Zuk is an evolutionary biologist, I give her opinion some weight and look forward to reading her book. I’ll probably review it and will mention her citations. Just like vegetarianism, I feel some people treat paleo as a fad diet and often don’t take the time really read the scientific literature supporting each. That’s unfortunate because I agree that have more in common than we think. If you were to boil down both ideologies (plant based living and paleo) you’d probably come up with the common denominator of: don’t eat cr*p.

      Thanks again for your comment,

      Beth 🙂