A few years ago I wrote a balanced, but still unfavorable review of a book that claimed to debunk the paleo diet called Paleofantasy: What Evolution Really Tells Us about Sex, Diet, and How We Live. Not being entirely unsympathetic to the message of the book, I followed it up with an article of my own about things I frequently heard from paleos that just weren’t quite right.
Since then, I’ve greatly furthered my own education on nutrition, evolution, and biology. Research has also moved on, and many of the prominent paleo writers have revised their recommendations. I’ve found myself wondering, is the paleo diet still even really the paleo diet anymore?
Many times I’ve contemplated changing the name of the Paleo Diet post category of my blog to Ancestral Health or even just simply Nutrition.
The flash point came when I received this comment on my review for Paleofantasy:
… To Paleo followers science is all well and good until it threatens to debunk their little caveman fantasy, and then it’s a strawman. If I had a nickel for every time I read a Paleo follower blathering on about how of course lactose tolerance proves evolution is still working but then turn around and claim we’re adapted to some arbitrary, meat-centered diet from Ice Age Europe, I’d be rich…
I happen to think this commenter’s analysis is flawed–more on that later. But I figured it was high time to put my thoughts to paper on whether “The Paleo Diet” as such is still a meaningful concept or just a fad that has passed its time (“If it’s a fad, then it’s a 2 million year old fad!” sound bite notwithstanding).
What exactly is the Paleolithic anyway?
As the commenter on my Paleofantasy review says, the Paleolithic evokes images of cavemen and ice-age Europe. The famous cave paintings at Lascaux and Neanderthals also probably come to mind.
Paleolithic literally means “ancient stone” and is the name given to the era of stone tools. However, the Paleolithic is much longer than most people think. It starts around 2.6 million years ago with the first stone tools and ends about 10,000 years ago as civilization as we know it began to take shape.
The Paleolithic era is often referred to interchangeably as the Pleistocene era, though strictly speaking the two are not the same. They begin and end at approximately the same times, but the Pleistocene is a geological era demarcated by a series of repeated ice ages ending with the last ice age about 10,000 years ago.
Significantly for us, the first members of the genus Homo also appear around the same time the Paleolithic and the Pleistocene began. It was, after all, our forebear, Homo habilis, who was making most of the early stone tools. Depending on estimates, Homo sapiens–us–appeared in Africa around 150,000 – 200,000 years ago, and started leaving Africa to populate the rest of the world around 60,000 years ago.
During the Paleolithic we shed our fur, learned to cook with fire, developed ever more sophisticated hunting tools, began leaving piles of bones from animals we had consumed, our brain size increased 2-3x, and at some point we began to speak to each other. Paleolithic history is to a large extent the history of us as a species and the era in which we evolved most of our distinctive features.
Evolution and human diet
I’ve never once doubted that evolution can tell us something about a healthy human diet. As eminent geneticist and biologist Theodosius Dobzhansky famously said, “nothing in biology makes sense except in the light of evolution.”
We not only need to inquire into human evolution, but into the evolution of the plants and animals that we eat as well. Sweet tasting fruits like berries and apples often have a happy co-evolutionary relationship with humans and other animals. In the wild, they provide us with a rich source of sustenance and in return we help them reproduce by spreading their seeds around through defecation or simply discarding them after consuming the tasty parts.
Edible seeds, nuts, and grains often have an antagonistic evolutionary relationship with humans and other animals. In their case we do not help the plants reproduce, but rather consume the reproductive parts directly. Plants often retaliate with chemical warfare by evolving compounds that damage our health or fertility. And indeed today, nut allergies are among the most prevalent, while blueberry allergies are all but unheard of.
That said, as I mentioned in the opening, the name paleo diet has been troubling me for years. We aren’t, and never were, trying to literally recreate the Stone Age and the glory days of hunter-gatherers before the “evils” of farming took root and we started growing amber fields of pain.
Since the end of the Paleolithic, farming has also dramatically changed the selection pressures on plants. Now we grow massive fields of grains, and plants like wheat do reap enormous reproductive benefits from our activities–but we should not rashly jump to the conclusion that nuts, seeds, and grains have fully disarmed their WMD arsenals since signing the peace treaty.
What Paleofantasy says about the paleo diet, and what I think of the book today
The main argument of the book with regards to the paleo diet is that evolution never stopped and there was no single, monolithic diet in the paleolithic to begin with. The paleo diet is, therefore, debunked. Never mind that neither of these were claims paleo authors were making to begin with.
I knew I was drinking the paleo diet Kool-Aid pretty hard around the time I reviewed Paleofantasy. So I put extra effort into keeping the review balanced, and tried to avoid it turning into a simple knee-jerk reaction piece.
However, time and distance have given me more perspective on both the paleo diet and criticisms of it raised in the book. As I was re-reading my review, I was pleasantly surprised to find that I still stand behind my main points. In fact, if I were writing the review again today I would probably only give the book one or two stars instead of three.
It’s painfully evident that whenever Zuk refers to prominent paleo authors like Mark Sisson and Art DeVany, she either did not actually read her sources or deliberately took them out of context. Had she been more thorough, she would have realized that in some cases not only was she not refuting their claims, she was actually retreading material that they had already been writing about for years–especially her two cornerstone points about lactase persistence and increased amylase CNV.
As much as I found Paleofantasy entertaining when Zuk was simply taking us on a tour of studies related to evolution and the human condition, the glaring problems with her coverage of paleo authors leaves me with a gnawing concern about the accuracy of her representation of research in the rest of the book.
While the name paleo diet still sits somewhat uneasy with me, the content of authors’ actual prescriptions does not. Another reviewer of Paleofantasy encapsulates what may be my biggest concern about the book: “… Zuks [sic] book could dissuade people from acting responsibly regarding diet…”
Should we still call it the paleo diet?
Mat Lalonde put it best when he said that the paleo framework is best thought of as a framework for hypothesis generation. To that extent, I think the watershed mark of approximately 10,000 years ago when farming began to rapidly and dramatically change dietary composition is still a salient point in history for generating hypotheses about what types of foods humans might be best suited to.
As I replied to the commenter on my review, Zuk provides no evidence of any dramatic species-wide changes in humans in recent history. The best we have on offer is a simple mutation in an enzyme that the body already produced–lactase–that is only present in about 35% of the global population. This does not contradict, but rather supports the notion of human evolution as a slow process that hasn’t produced much more than cosmetic change in recent history. And in no way constitutes proof that the human body is completely malleable to whatever you feed it.
Inter-individual variation certainly exists, but the evolutionary framework is still very salient. That is a take home message that paleo authors have already been writing about for years. Chris Kresser exemplifies the “paleo template” approach in his book.
That said, in my view paleo authors have been drifting more towards what I would call evidence-based nutrition in recent years.
Foods like white potatoes that were not originally considered paleo, are now considered paleo by many folks because selective farming has reduced the alkaloid content to the extent that they are no longer poisonous like many other nightshades. Yes, I really just said that. Farming techniques in the neolithic have made these foods “paleo.” If you find that a head scratcher, you are in good company.
So should we still call it the paleo diet? I really don’t know. I was hoping that by the time I got all my thoughts out on paper I would have a clear stand on the matter, but I’m still irresolute.
However, I do think the dietary recommendations of authors like Mark Sisson, Chris Kresser, and others that broadly fall under the paleo monicker are sound and worth following. If Paleo Diet is the catch phrase that directs you to their work, then I think your health will be all the better for it.
If the findings that have come out of the paleo movement are at all valid, and I think many of them are, they will eventually fold into mainstream nutrition. While we have seen slight shifts in this direction, by and large it hasn’t happened yet. I’m sure the dietary landscape will continue to evolve in the years to come, but for now perhaps the paleo diet is still what we need.