Paleofantasies of the perfect diet – Marlene Zuk in NYTimes
Posted by gregdowney on January 21, 2009
Prof. Marlene Zuk (University of California Riverside), author of Riddled with Life: Friendly Worms, Ladybug Sex and the Parasites That Make Us Who We Are (Amazon, Google books), has a very nice short essay in The New York Times on the recent discussion of whether or not our dietary problems stem from our bodies being ‘out of step’ evolutionarily with things like Mars bars and Big Macs: The Evolutionary Search for Our Perfect Past. We’ve seen these sorts of arguments all over the place, that a ‘Paleolithic diet’ can make you healthy and banish bulges from inopportune places, after all, just look at Raquel Welch in 10,000 BC!
Paleolithic dieter? Not exactly...
When I talk about diet and human evolution in my freshman class, I have to point out that there are a tremendous number of complications, including the fact that the vast majority of us do not have the cultural knowledge to get ANY nutritional resources out of the environment around us (see my earlier post with my slides from that lecture, if you like). It’s all well and good to say, ‘Eat meat, roots and berries,’ but that just means spending our time in the grocery store aisles a bit differently for most of us, not actually transforming the ways that we get food, how we relate to our environment, or even the quality of the meat, roots and berries we’re getting (after all, even the meat we get is from the animal world’s equivalent of couch potatoes, not the wild stuff on the hoof– or for that matter, dead on the ground where we can scavenge it).
Zuk draws on Leslie Aiello’s concept of ‘paleofantasies,’ stories about our past spun from thin evidence, to label the nostalgia some people seem to express for prehistoric conditions that they see as somehow healthier. In my research on sports and masculinity, I frequently see paleofantasies come up around fight sports, the idea that, before civilization hemmed us in and blunted our instincts, we would just punch each other if we got angry, and somehow this was healthier, freer and more natural (the problems with this view being so many that I refuse to even begin to enumerate them). It’s an odd inversion on the usual Myth of Progress, the idea that things always get better and better; instead, paleofantasies are a kind of long range projection of Grumpy Old Man Syndrome (‘Things were so much better in MY day…’), spinning fantasies of ‘life before’ everything we have built up around us.
Zuk describes how, she was initially enthusiastic about the ‘evolutionary mismatch’ argument around health and diet, but that, upon closer inspection: ‘The notion that there was a time of perfect adaptation, from which we’ve now deviated, is a caricature of the way evolution works.’ Zuk asks which particular stage in hominin evolutionary development was the age at which we were perfectly in harmony with our environment:
How much of the diet during our idyllic hunter-gatherer past was meat, and what kind of plants and animals were used, varied widely in time and space. Inuits had different diets from Australian aboriginals or Neotropical forest dwellers. And we know little about the details of early family structure and other aspects of behavior. So the argument that we are “meant” to eat a certain proportion of meat, say, is highly questionable. Which of our human ancestors are we using as models?
In fact, the idea that our bodies were perfectly suited to a particular environment is an adaptationist fantasy. Processes of evolution, including variation and natural selection, niche creation and co-evolution, even catastrophe and fluctuating rates of evolutionary change, suggest that adaptation is usually imperfect, with abundant glitches that, as long as they don’t constitute abject failures, usually continue to exist unless selection and variation conspire to find a way to get rid of them.
We have never been a seamless match with the environment. Instead, our adaptation is more like a broken zipper, with some teeth that align and others that gape apart. The paleontologist Neal Shubin points out that our inner fish constrains the human body’s performance and health, because adaptations that arose in one environment bedevil us in another. Hiccups, hernias and hemorrhoids are all caused by an imperfect transfer of anatomical technology from our fish ancestors.
I’ve been recently reading a book that I have to review which follows this line of thinking: that evolution shaped us for one sort of environment, but that civilization, technology, social life, and culture all demand something radically different from us, so we’re stuck. There’s an odd inconsistency there: on the one hand, we’re perfectly adapted to paleolithic life; on the other hand, our bodies just can’t get with the last 10,000 or 50,000 years of change. Usually the argument is that ‘we’re just changing too fast now to adapt.’
I think the biological evidence points to the fact that both of these impressions is incorrect, as Zuk suggests: we are neither so perfectly well adapted to foraging (or scavenging or living in trees or whichever stage we develop paleonostalgia for) nor are we so ill-suited for our own environment (in spite of our health problems, we actually live a long time compared to our ancestors, for example).
So before we start waxing nostalgic about all the health benefits of a Pleistocene diet, perhaps we should remember that our ancestors’ food often came in this nasty packaging which tended to run away, attack them, or just go missing entirely when they were really hungry. Zuk’s conclusion is a very balanced one:
This isn’t to say that we wouldn’t be better off eating fewer processed foods. And certainly we have health concerns that never struck our ancestors. But we shouldn’t flagellate ourselves for having modern bodies, and we shouldn’t assume that tweaking our diets or our posture will rescue us from all our current ills. That’s just a paleofantasy about the future.
We are, quite simply, a species of our Age, shaped by the environmental forces around us, just as our ancestors (and us) were also shaped by their Age (whether the Holocene, Pleistocene, or earlier). We drag the history around in our bodies, but we also bear the stamp of our own time, especially in things like diet, as the food choices we make end up affecting the very molecular structure of our bodies and brains. I don’t think we’re fat or have heart disease or live longer because we’re stuck in Stone Age bodies, but rather because we’re fashioning Information Age regimes of food, activity, and environments. We tend to look at our bodies and see their inadequacies, but we could just as easily see them as the perfectly logical products of the developmental processes we create, for all their strengths and weaknesses.
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[...] Paleofantasies of the perfect diet – Marlene Zuk in NYTimes … [...]
Peter said
This article shows a woeful lack of understanding as to how evolution works and seems to be written by someone to whom science is one big mystery. I am no wiser after reading it as to what the author proposed that I do eat, or why.
The arguments put forward by Pale Diet proponents such as Loren Cordain are clear and logical – in stark contract to the fuzzy thinking in this article. I just couldn’t be bothered putting up counter arguments; it is nearly midnight here and I don’t want to be up until sunrise.
Just read Cordain’s book or subscribe to his website. The logic is clear, the only argument is to exactly what foods made up the hunter-gatherer diet, but these are only at the margins. The fact that we evolved for 2 million years on a diet which did not include grains, legumes, dairy products, refined foods or refined sugar is uncontested. The Paleo diet is pretty much what is left over when you take those things out, and make some well educated adjustments in the types of fat we eat – again, based on very clear logic.
gregdowney said
Dear Peter —
Just because something is ‘clear and logical’ does not mean that it is either correct or accurately represents the available data. Much of the data on diet over the course of the last two million years is, in fact, ‘fuzzy.’ It would be great if it were not, but it’s hard to know exactly what was happening in pre-human hominin diet. Even what we thought we did know from evidence of jaw structure and tooth enamel wear turns out not to always be quite so clear.
For example, there’s some interesting recent research on the robust australopithecenes (sometimes now classified as the genus, Paranthropus) that undermines what we thought about their diet. With huge skeletal structures for anchoring jaw bones and massive molars, the evidence looked conclusive that their diet involved mostly grinding up gritty roots and tubers. But new evidence suggests that they might have eaten a large proportion of fruit, relying on what we thought was their dietary staple in times of stress.
‘Clear logic’ in evolution is often adaptationism, the assumption that we are perfectly adapted to our environment or that every human trait is necessarily selected. Increasingly, we’re realizing that’s not the case, that selection works on the whole organism, and because genetic sequences are pleitropic, or expressed in different ways in multiple organs, we’re often not perfectly adapted.
If Cordain’s diet works for you, great. But that hardly proves its accuracy for describing prehistoric diet, nor does it smooth over the interesting intellectual questions about the role of diet in our development as a species. It’s not ‘fuzzy’ thinking just because it doesn’t provide simple answers.
For example, one point I made was that much of our ancestors’ meat intake at early stages of hominin evolution was likely not the sort of meat we’d like to eat today. For example, it may have included a lot of small game – lizards, insects, small birds, carrion scavenged off of other animals’ kills – and it’s not clear when cooking came into the equation. We also know that our ancestors had very different tooth wear patterns, and they likely had an interesting array of parasites. Must Paleo diet advocates would NEVER advocate moving to a diet of uncooked small game or carrion — I can’t imagine that book would be a best-seller! But the evidence even from sophisticated contemporary foragers, groups that lived mostly by utilizing food sources occurring without complete domestication, is that they aren’t very squeamish.
Another issue is something like fiber; odds are that our ancestors got a hell of a lot more of it than we do in refined foods. But there’s a chance that this would mean a LOT of time spent chewing (and a lot of poop, for that matter!). Richard Wrangham, a biological anthropology at Harvard, has done some research on what it’s like to eat a chimpanzee diet, and from his descriptions, I feel for the guy. He says it’s pretty foul: tough, fibrous fruits, some of which are pretty bitter and a few that made him heave. Not only are our jaws inadequate (many of our ancestors’ were quite a bit more substantial) and our guts are just too short and under-strength to get the necessary nutrients out of the food.
I think it’s great that Cordain recommends eating less high-GI and processed food; hell, I grow some of my own food and eat local here in Australia. But that doesn’t mean it’s a ‘Paleolithic’ diet. That would involve some more radical changes than most of his readers are ready for.
little d, S.N. said
Peter, another thing I feel is worth pointing out is that hominids (especially foraging humans pre-agrarian revolution) DID eat grains. They ate pretty much anything they could get their hands on, and that would have indeed included cereals when in season, and legumes whenever they could have been dug (including cattail tubers). When a population is foraging, they will eat pretty much whatever won’t kill them in an environment. Hell, in South America, foraging populations would even mash toxic potatoes with clay to leach the toxins, and eat them anyway!
I suppose my point is that humans never had it easy, and while I am totally in favor of eating a more balanced, healthy, high-fiber diet, human life was seldom a matter of wandering about in a huge berry-and-easily-caught-animal-filled garden.
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[...] self-indulgence, I would like to direct you to a very enlightening post over at Neuroanthropology, Paleofantasies of the perfect diet. I have posted a few times here on the topic of what has become to be known as “evolutionary [...]
Irradiatus said
This is such an enlightening article!
As far as Peter’s claim that “This article shows a woeful lack of understanding as to how evolution works and seems to be written by someone to whom science is one big mystery,” it is incredibly clear that this statement is utterly, exactly wrong. And I’m incredibly impressed with your response…
I think your point about the small game issue is a great one. There’s little doubt that various groups of early humans often subsisted on lizards and insects and such, yet I can’t imagine anyone today recommending these as staples in the paleonostalgic diet.
Kudos on a wonderful article!
Tim Jones said
Another item on the Palaeo diet would appear to have been other humans – going all the way back to Atapuerca, and at various sites where it has been suggested that human bones appear to have been deliberately smashed in order to extract brains or marrow – I daresay such food would be nutritious, but personally I’d prefer a Mars bar any day of the week.
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[...] I suspect that I usually disappoint my students, who can be pretty fervent about these ideas. Most paleo-nostalgia movements seem to me to be very selective – for example, the whole Paleolithic Diet movement seems to overlook a host of problems, such as changes in activity patterns, the difference between wild and domesticated meat animals, the high incidence of parasites and low life expectancy in prehistoric periods, and the likelihood that much of human protein was not coming from delicious medium-rare steak or grilled chicken breasts but rather invertebrates, shell fish, small vertebrates, offal and carrion (that’s right, maybe it should be the ‘Bugs, Clams, Lizards and Roadkill Diet’ – not quite the same marketing potential as ‘Eat All the Steak and Chicken You Can!’). I’ve discussed this in Paleofantasies of the perfect diet – Marlene Zuk in NYTimes. [...]
Dean Romano said
Thankfully I don’t have children at University of California Riverside or they may have had the misfortune of having Ms. Zuk as an instructor. Having grown up on a large working farm I don’t think she can grasp the true immensity of how food is gathered in the wild and why we as humans can only truly be healthy eating certain fruits, vegetables, and meats. She’s truly ignorant
Sceptical said
Don’t forget insects for your Paleo diet. Lots of animals thrive on eating insects, including some primates.
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