Some months ago I started pondering the paleo diet, or some of its purveyors and adherents, as possibly embodying a concept akin to The Self-Justification Diet™. Understanding that this tendency springs from the confirmation bias we all share, I first broached the subject by pointing a satirical finger at myelf. The cognitive bias is bad enough in individuals, but when combining it with the social element of the herd instinct bias we may see a feed-forward effect resulting in self-assortment feeding ingroup bias which feeds back to our own confirmation bias. Since the paleo diet delves into areas of human instinct, it is basically impossible to prevent the propagation of certain ideas in a memetic fashion. As hinted in the title, the question of fat is a point I’d like to subject to some scrutiny in these terms.
The Disconnect
In the paleosphere, there’s a sometimes explicit, otherwise tacit, understanding that the SAD flourishes because of evolved human proclivities for sugar, salt, and fat. Our modern system of hunting and gathering from well-lit aisles and laminated menus hijacks the prehistoric nutrition plan delivered by our instincts. This narrative certainly isn’t limited to the pop-evolutionary biology that’s bantered about the pop-paleo community; it’s recited in a variety of contexts…
I haven’t heard anyone challenge the instinctual human drive for fat, salt, and sugar. Until further notice, I’ll assume it’s a generally accepted principle among the paleo community participants who believe the paleolithic was an actual period of time, before Adam and Eve, during which the genus Homo evolved.
It’s on this foundational assumption that the paleo logical framework is formed – the very framework that provides an ultimate explanation for why our instincts aren’t to be trusted regarding food choices in our mismatched grocery store and restaurant culture. It is this logical framework that underpins the large constituent of paleo proponents who minimize fruit consumption in outright defiance of the fact that fruit consumption in our evolutionary past was high enough to allow our genes that coded for vitamin C synthesis to be deactivated.
When it comes to fat, a rejection of the shoddy research of Ancel Keys seems to be all that’s needed to make the logical leap to also rejecting the “lean game meat” conception of paleo forwarded by the likes of Loren Cordain, PhD. and Arthur De Vany, PhD. On the basis of the paleo logical framework, it’s incongruent to reject the unrestricted consumption of fruit and also advocate the unrestricted consumption of fat. For that matter, it’s similarly incongruent to reject grain consumption based on the paleo logical framework whilst recommending the unrestricted consumption of fat. If you like fat (and you do), fine. Eat whatever you want. But… keep in mind that there is almost certainly a limit to the amount of healthy fat consumption, and our heuristic “eat more fat” instinct will push some across the line into rationalization in service of self-justification.
“But… but… the science, Andrew… what about the science?”
Positivist Paleo
The [paleo] positivist has little-to-no use for logical frameworks. In the grasp of positivism, logic is little more than a cutesy anecdote that may be useful for the generation of hypotheses. In this world of orthodox empiricism, claims cannot be made absent positive verification by way of controlled experimentation and commensurate data.
Unpacking this concept of paleo positivism reveals something. At its most fundamental core, paleo (whether we’re relating it to diet or mind) is nothing more than logical framework. Perhaps strangely, this is true regardless of the depth of insight archaeology or anthropology may impart upon us with respect to any given question. Even if we knew exactly what a common ancestral population consumed across their lifetimes, it would remain necessary to invoke a (Darwinian) logical framework to begin to make prescriptive assumptions about what we should eat in the modern world. In its requisite minimization of the importance of the logical framework of paleo, positivist paleo renders itself an oxymoron – by definition. Despite that slight problem, it is still possible to act as a paleo positivist. The underlying truth is that the paleo positivist may as well simply be called a positivist.
The sure way to escape the positivist program is to recognize the value of paleo logic prima facie, or… as the null hypothesis. If that stance isn’t taken, ‘paleo’ is little more than a rather hollow moniker.
Some may erroneously take the preceding paragraphs as an affront to science. That certainly is not my intent. Rather, my ardent rejection of positivist paleo is based on the sober recognition that science is likely to fall far short of definitively answering many important questions in our lifetimes. It’s in these areas of incomplete research that our instinctual drives to consume are insidiously (read: unconsciously) blurred and obscured most acutely. To my mind, building a bridge from rejecting Ancel Keys (and/or the lipid hypothesis) to rejecting Dr. Cordain and Dr. De Vany is an area fraught with risk of this bias. Just as the modern apple and banana have been shaped by the sweet-tooth of H. sapiens, the modern meat supply has been shaped by our inherent lipid love – grass-fed included. Rather than adjudicating based on sparse data that appears to maybe kinda point one direction, I’m comfortable starting with the assumption that paleo logic provides valuable insight. And I’m not going to hold my breath while the science community plays the endless games of grants and funding and ethics panels and various other political wrangling.
Now if you’ll excuse me, I found a new source of butter in the local grocery store. For some reason, they hid it in the cheese section.
Check here: http://evolvify.com/the-semiotics-of-meat-paleo/
Note that the meat from game animals did contain some vitamin C. I suspect meat from grain-fed/grain-finished animals will show lower concentrations of vitamins. Taubes mention in Good Calories, Bad Calories that carbohydrate consumption increases the need for vitamin C. Not sure about your assertion that our distant ancestors ate enough fruit (year-round, mind you) that our machinery for making our own vitamin C was redundant and therefore deactivated.
"Meat", as it exist in the grocery store, does not contain significant amounts of vitamin C. It does exist in the skins of some marine mammals and some organs of terrestrial mammals. If you're a grocery store hunter-gatherer, the only way to get vitamin C is through plant sources or supplementation. It's almost the reverse of the B12 argument against veganism.
The vitamin C bit is not an assertion, but a well-researched concept in evolutionary biology. I wouldn't quite phrase it that the machinery was "therefore deactivated". It's more accurate to say that over extended periods of high fruit consumption, sufficient selective pressure against the mechanism's genetic deactivation would not have been present.
I wonder if fruit has unknowingly been bred to contain more vitamin C along with the more purposeful sugar component.
That may be a hard case to make considering that men tend to develop scurvy when left to their own devices.
Doesn't have anything to do w/ vitamin C, but I remember hearing this in the news a couple months back… The discovery of a new type of tangerine, found because the growers observed baboons preferentially stripped that tree of fruit before any other. Of course it turned out to be sweeter!
http://www.msnbc.msn.com/id/41058945/ns/technolog…
I just made the comment on Hunt, Gather, Love that for me 'paleo' is a starting point not the end destination.
What that end-destination will be I don't know, if there even is one.
More likely continual learning and adjustment until the end.
Correct.
Eating too much fat was a major stumbling block for me, driven by paleo dogma.
However, incorrect about fruit. Neither my dad nor I can tolerate it.
Just because we have some genetic capacity to consume something, doesn't mean it's nutritionally optimal.
Experimentation uber alles.
Here's my post describing the 100% meat diet that finally cured me:
http://www.josephdantes.com/blogs/shorts/?p=552
"However, incorrect about fruit. Neither my dad nor I can tolerate it."
There's always variation within a species. This sort of variation is the exception that proves the rule (of Darwinian evolution).
The phrase "the exception that proves the rule" is not true simply because a lot of people have used it and it has become embedded in our thinking. Something is proven when all of the facts support it, not just some of them or most of them. To use an exception as proof is most illogical.
The idiom isn't meant to convey scientific "proof"; it refers to the reason for the existence of the rule in discourse. If there were no exceptions, uttering such a "rule" would be recitation of a truism, and thus, no rule would need be necessary.
Perhaps Wikipedia explains it more eloquently…
"The original meaning of this idiom is that the presence of an exception applying to a specific case establishes that a general rule existed."
Andrew,
I agree almost entirely with everything you say about bias. I don't entirely agree with all of your conclusions.
First, I eat fruit, and I think the evidence that fruit, even modern fruit, is bad for you, is almost non-existent if you do not have fructose malabsorption. Nevertheless, nonhuman primates can't synthesize vitamin C either, so I don't think you can use this fact to argue that fruit consumption was very high during human evolution. There's no reason to think that humans need the same supply of vitamin C as other animals that synthesize it or even as other primates that eat lots of fruit. If we can lose the ability to synthesize vitamin C, we can also develop a different need for vitamin C.
I agree with you that it is incongruent to place restrictions on fruit consumption but not fat consumption when there is not much evidence justifying either restriction, but when it comes down to it there is also not very clear and reliable evidence how much fat or fruit paleolithic people were eating.
I fully agree with you that a logical framework should be used for action in the face of uncertainty, and not just for generating hypotheses to be tested experimentally. If logical frameworks were restricted to the latter, we would be paralyzed and unable to act on anything because experimental evidence is so slow to develop and because uncertainty always remains about which populations and which individuals and which overall contexts we can safely generalize the results of an experiment to.
However, I think it is mistaken to use the logical framework to *dictate* actions rather than as a guide to test actions by trial and error. Ultimately, I eat fat because I get hungry if I don't eat enough and when I'm hungry I can't sleep at night. Ultimately, I eat carbohydrate because my mood is better, I'm calmer, and can fall asleep better. Ultimately, I eat nutrient-dense foods because they have improved my health. If any of these experiences contradict a logical framework, the framework has to bend to personal experience.
Chris
We agree on assigning some value to n=1 experimentation. I think we drastically diverge in the value we're willing to ascribe to n=1 self-experimentation. Bias makes it hard enough to train scientists to draw useful insight from experiments on others. Turning everyone into objective simultaneous experimenters and experimentees strikes me as an infinitely utopian endeavor.
I find the notion of a sufficiently controlled and unconfounded n=1 self-experiment to be almost completely illusory. Further, the illusion expands geometrically with the time-scale in question.
I mean sure, it's reasonable enough to say things like "my skin consistently breaks out 4-8 hours after I eat Smurfberries so I don't eat Smurfberries". But even when you say you can't sleep at night because you feel hungry because you didn't eat enough fat, you're exposed to multiple subjective self-measurements and a potential cascade of psychological and cognitive traps on the way to drawing your conclusion. And… that question is orders of magnitude more simple than trying to figure out if Smurfberry induced inflammation during brain development will negatively impact the general intelligence of individual X.
Using the paleo framework as the null hypothesis just seems like the smartest course of action with respect to myriad questions. I think the bar of justification required to deviate from it is somewhere down around ankle level, and it seems to be getting lower in areas that The Self-Justification Diet™ would predict.
Andrew,
I agree that it is incredibly difficult to generate solid conclusions through self-experimentation.
I would go somewhat further to say that there is no such thing as an "n=1 experiment." A proper self-experiment, as opposed to a flimsily interpreted experience, would be to put oneself (preferably blinded with the help of someone else if possible) through several treatment and control trials in a randomized order, in which the "n" becomes the number of trials rather than the number of individuals. Then one can use statistics to determine if there is a treatment effect. This is obviously impractical in many scenarios.
I don't think "null hypothesis" is a fair way to describe what you mean. The "null hypothesis" is by definition the hypothesis that two things are equal, i.e. that whatever condition is being considered has no effect. To use a positive hypothesis that there is a difference as "null" is essentially to turn the concept on its head. I think you can argue for that, and you could make a case for it, but I think you'd have to call it something else like a "default hypothesis."
In any case, despite the difficulties inherent in interpreting personal experience, there should also be an "if it ain't broke don't fix it" principle operating. That is, if something seems to work, and continues to work, the fact that a problem is fixed and should remained fixed is more important than whether your beliefs about why it worked are correct. Maybe the sole reason I sleep better when I eat carbs is because of a placebo effect, even though there is good science supporting a role for carbs and insulin increasing transport of tryptophan into the pineal gland and across the blood brain barrier. But it's most important that I sleep. If I'm eating more carbs than Art De Vany claims paleo people ate, based more on his best guess than good evidence, so what? Getting the "right" macronutrient ratio according to someone else's best guess can't be more important than sleeping well.
Chris
Wresting "null hypothesis" from a statistical context and using it as I have doesn't sufficiently obfuscate its meaning. It's not even a novel use; Wikipedia actually defines it by the very alternatives you suggest I use: "The null hypothesis typically corresponds to a general or default position."
Continued:
"For example, the null hypothesis might be that… a potential treatment has no effect."
I'm using it in precisely this way – to suggest that paleo is a "potential treatment that has no effect", in contrast to neolithic deviations which would constitute alternative treatments and/or alternative hypotheses.
Continued again:
"In most legal systems, the presumption that a defendant is innocent ("until proven guilty") can be interpreted as saying that his or her innocence is the null hypothesis. Other legal systems may exist in which the null hypothesis is that the defendant is guilty."
Perhaps that mode works better for some: "Paleo. Innocent until proven guilty."
It's exactly the principle of "if it ain't broke don't fix it" that I reject. When the very concept of broken is a measure relative to subjective self-analysis, it borders on meaningless.
But…. But… Modern hunter gatherers have been observed eating bone marrow, brains, paw pads, and just about all of the fattiest parts of the animals they bring down. You could say they prize those organs much more than the actual meat. So, if modern humans eat the leanest part of fat animals, while hunter-gatherers eat the fattiest part of lean animals, then are you contending that the little extra marbling on my ribeye might be adding more fat to my diet than would be eaten by my ancesters who would regularly break open bones and suck the fat out?
Also what about someone like Matt Lalonde who rejects the evolutionary angle completely but still basically eats a paleo diet based on modern nutritional research?
I think Matt L. uses the anthropological evidence as a means of generating a hypothesis, not as conclusive proof. The modern research then is used to confirm or deny the hypothesis.
Proximate or Ultimate? I think both are of import, and not at all incongruent. I think most evolutionists would agree.
Your point that "most evolutionists would agree" is implicitly insightful.
Drawing a line between evolutionary biologists and biologists isn't the most useful example to demonstrate the importance here because it's difficult to be a non-evolutionary biologist. However, their is a huge (perceived) rift between evolutionary psychologists and psychologists in the focus on proximate causes or ultimate causes. Larger rifts in perspective exist between say… evolutionary psychologists and sociologists, or paleoanthropologists and chemists.
So yes, a "paleo positivist" would essentially discard ultimate explanations whilst replacing them with the proximate. It ends up as a sort of myopic love of the proximate.
It seems to me you are arguing that paleo=ultimate expanation and that "positivism" = proximate explanation. Is this not the case?
Neither Cordain nor De Vany are physical anthropologists, nor are they respected by that field. I'm confident that the data from the paper I am working on will shed ample light on the matter of evidence for high fat consumption during the paleolithic era. Whether or not that's relevant to what level of fat consumption is healthy is another matter…
I tend to pull for contrarians and outsiders so the lack of sanctioned respect by the field™ doesn't really phase me. The data are the data and I welcome new and improved insights.
Ultimately, this post isn't about ascertaining the healthy levels of fat consumption (fat is not even something I worry about), but wondering to what extent the framework of paleo is being watered down and negated by those who don't really practice, identify with, or don't care to be identified with, paleo. The disparity of treatment relating to evolved proclivities for fat (celebratory) and sugar (vilified) simply strikes me as odd from the context of ecologically driven evolved behavior. Both theoretically evolved because of relative scarcity (and similar aggregate benefit) in ancestral diets over significant periods of time. It's certainly possible that they evolved for different reasons, and I'm happy to entertain alternative hypotheses. Regardless of adaptive pressures AND health considerations, both instincts drive biases similarly and are therefore similarly capable of being considered part of The Self-Justification Diet™ .
What I've loosely described here as positivist paleo seems to be stripped of all actual paleo-ness only to be replaced with some sort of archeo-nutritionism.
It's funny because I've often thought the Loren/De Vany diets were the ultimate example of picking and choosing a narrative of the paleolithic to support pre-conceived notions of what is healthy.
I'm not as interested in this "paleo" thing that has been shaped by such nonsense. I'm interested in the actual era of the paleolithic and how it shaped our evolution.
What Melissa said
And for my part, I prefer an archeo-nutritionism which draws from multiple lines of evidence, including "non-paleo" ones, to a fantasized idea of what is "paleo", esp. when it is supported by no actual knowledge of the paleolithic period, which was hardly a static continuous biome anyway.
"Both theoretically evolved because of relative scarcity (and similar aggregate benefit) in ancestral diets over significant periods of time."
This is, it seems to me, the hazard of paleo reasoning. To put an armchair observation about how something theoretically evolved above, or even equal to, modern knowledge of how, say, saturated fat and sugar are metabolized. Yes, they both taste good, but to even remotely entertain their dietary moral equivalence you would have to ignore an awfully large volume of non-paleo knowledge.
Characterizing what I've written here as placing paleo reasoning above good data doesn't accurately represent my thinking. My estimation of nutritional science is that there is a relative dearth of good data that rises above the level of overly reductionist nutritionism. Thus, proclamations of things that are "good" or "healthy" tend to be made at the mere presence of nutrients that are known to be beneficial or necessary without respect to the negative constituents also contained within.
I'm not playing the dichotomized modern science vs. paleo logic game that a paleo positivist would. I'm saying that absent good data on any specific question, the paleo framework is useful, and highly likely to be vindicated if and when Science™ gets around to answering the question anyway. And… I have a suspicion that I'm going to get hungry before Science™ gives me permission to eat some of the things in my fridge.
I definitely place paleo reasoning "above" science in terms of practical usefulness for the layperson, but that's not the same question as adjudicating between the two when they both have something to say.
All the while, I fully recognize that our knowledge of all things paleo is always incomplete and often problematic. Like you and Melissa, I'm all for getting the best information possible. Now, I don't happen to view the extant paleo hypotheses and literature as "nonsense" so much as science (in its active process) rather than Science™.
"Characterizing what I've written here as placing paleo reasoning above good data doesn't accurately represent my thinking."
Perhaps I misunderstood your post. Cordain and Devaney wrote books packed with highly speculative paleo reasoning that is unsupported by actual science (whether it has an ironic TM appended to it or not).
Characterizing the rejection of Cordain or DeVaney as merely a hazardous and reactionary response to Keys is quite a cartoon view of my views as well. As if my views were based on nothing else.
"My estimation of nutritional science is that there is a relative dearth of good data that rises above the level of overly reductionist nutritionism."
No argument there. And that goes double for people writing things that no paleoanthropologist would find remotely plausible or even knowable.
"Thus, proclamations of things that are "good" or "healthy" tend to be made at the mere presence of nutrients that are known to be beneficial or necessary without respect to the negative constituents also contained within."
Awkward, but I think I get what you are saying. I don't disagree but I fail to see the relevance to our disagreement here. Unless you think we are not allowed to consider what foods contain, or just trying to stop debate, which IMO is often why the epithet of "nutritionism" is hauled out.
You don't see me advocating extraction of saturated fat for parenteral infusion. I advocate whole foods and eating nothing more processed than butter.
Some foods are better than others, unless you want to stay above the fray and be a nihilist.
I disagree with Devaney and Cordain about which foods are good because I believe the science I've read and the errors in their unsupported "paleo" reasoning make the case.
"I'm not playing the dichotomized modern science vs. paleo logic game that a paleo positivist* would. I'm saying that absent good data on any specific question, the paleo framework is useful, and highly likely to be vindicated if and when Science™ gets around to answering the question anyway. And… I have a suspicion that I'm going to get hungry before Science™ gives me permission to eat some of the things in my fridge."
Even though I don't pack my prose with as much metaphysics as you like to, I'll see your name-calling and raise you one. I see plenty of positivism in your writings here, yet more cynicism in your whole approach. I get that you are trying to be in a "meta" relationship to the rest of us, who are stuck in the muck of normal discourse, and trying to say something useful to those who have to eat something. I do find your posts very clever and entertaining, even if at the expense of effective communication.
As far as "absent good data" are you claiming that Cordain and DeVaney have good data upon which to base their warnings on saturated fat? I assume you think that they do if rejection of their claims is "hazardous".
"I definitely place paleo reasoning "above" science in terms of practical usefulness for the layperson, but that's not the same question as adjudicating between the two when they both have something to say."
That surprises me. Maybe if you could define paleo reasoning in a few sentences or what paleo even means, I might understand a position like that.
"All the while, I fully recognize that our knowledge of all things paleo is always incomplete and often problematic. Like you and Melissa, I'm all for getting the best information possible. Now, I don't happen to view the extant paleo hypotheses and literature as "nonsense" so much as science (in its active process) rather than Science™."
Which extant paleo hypotheses do you view as "science"? I am curious. Do you disagree that some of them are nonsense? Where is the "science" behind eating copious nuts and nut butters and throwing away egg yolks in favor of the whites? Just asking. And if these are scientific hypotheses, then the process can legitimately include people calling ideas that are unsupported "nonsense" – as in "does not make sense".
Science is not special in that way. It is just a type of conversation and can include calling bullshit when necessary.
*I assume "paleo positivist" is an insult.
You ask some interesting questions here that are worth considering, but I’m inclined to perform some structural maintenance on the conversation before proceeding.
“I’ll see your name-calling and raise you one.”
Time out.
You misstated my position in your previous comment by saying my quote amounted to putting “paleo reasoning… above… modern knowledge”. My entire response was simply an ad hoc clarification of my own thinking. I was speaking generally and in reference to the ideas forwarded in the original post, and didn’t so much as refer to you or raise a single argument against you. I didn’t even use the word “you” other than to agree in the last paragraph.
“Characterizing the rejection of Cordain or DeVaney [sic] as merely a hazardous and reactionary response to Keys is quite a cartoon view of my views…”
Where did I assert that your views can be accurately represented as such? I read a lot of paleo related blogs, comments, and other secondary discussions. Whatever ambiguous cartoonish characterizations I make are distillations of perceived trends and commentary on the zeitgeist as I see it. If something specific sufficiently rankles my sensibilities, I’ll address it directly.
That’s about all I have time for tonight so the salient questions will have to wait a bit.
I guess I am not smart enough to understand what you write. My apologies.
When I read:
"The [paleo] positivist has little-to-no use for logical frameworks. In the grasp of positivism, logic is little more than a cutesy anecdote that may be useful for the generation of hypotheses. In this world of orthodox empiricism, claims cannot be made absent positive verification by way of controlled experimentation and commensurate data."
I thought, having read the post in toto, you might be saying that those who think Cordain and DeVaney are wrong to fear saturated fat are "positivists" and "orthodox empiricists" who "have little to no use for logical frameworks" for whom "logic is little more than a cutesy anecdote" – that those of us so inclined are essentially maintaining that nothing bad can be said about saturated fat without empirical data.
Now I see that you were not referring to me as belonging to such a general class – these positivists who have no use for logic or logical frameworks.
So who are the representatives of the "positivist" zeitgeist of which you speak? I'd like to read them, as now it is not clear to me who they are. Are you saying you were referring to yourself?
Also, as far as the modern meat supply differing a lot from the archaic in available fat, you might see this and some of my other recent posts:
http://www.archevore.com/panu-weblog/2011/4/7/lea…
I love your 2nd paragraph, except the absence of recognition for n=1 self-experimentation.
Living in modernity is much harder for some than others.
Your science and evidence based hierarchy of nutrients that placed potatoes and root tubers well above rice was very very wrong for me, and probably for others.
The case against rice? Stripped of its husk, the way normal people eat it? That it's empty calories, contains no extra nutrients beyond starch.
Well, that's perfect by me. I already get all my micronutrients from meat – beef, fish, shellfish. All I need is some starch to replenish my glycogen stores during strenuous athletic activity.
But due to my fructose intolerance and generally sensitive gut, I kept failing out every time I tried to introduce carbs, because the potatoes and tubers were too tough on me.
It's a case where all the scientific evidence in the world can be stacked up with the wrong hierarchical prioritization to create a very misleading picture.
A real paleo movement needs to incorporate much more robust individual vitality tracking and strict, easy to implement starting all-meat 1 week baselines to allow people to find their max health point and then expand the diet outwards in a way that avoids any intolerances they may be susceptible to.
Otherwise, whether you say "eat fruit" or "fruit is bad" you're not really changing people's lives to the maximum extent possible.
I'm comfortable with my deconstruction of the "Fatty domestic meats" section of Dr. Cordain's "Origins and evolution of the Western diet":
http://www.gnolls.org/715/when-the-conclusions-do…
Warning: contains lots of gritty detail, data tables, and recalculated regressions. I'm not Denise Minger, or even Melissa McEwen, but I'm reasonably confident in my work.
JS
I think we should temper suggestions that North American Holocene populations are a reliable source from which we can reverse-engineer an accurate representation of Pleistocene Africa. What you show is that people will tend to optimize their calorie harvesting strategies in a heuristic “maximize calories while minimizing work” manner. Other H-G bands subsist on 100+ species harvested opportunistically.
Perhaps counterintuitively, that the heuristic doesn’t seem to have an upper limit (as is also demonstrable by modern obesity) is actually an indicator of scarcity across the EEA; it hints that the examples you provide may be from evolutionarily novel ecologies.
From another angle, it’s not unreasonable to think the Inuit and other North American populations underwent strong adaptive pressure based on their diet in a compressed timeframe. If so, it’s possible their descendants are better adapted to the “Inuit diet”.
I’m also not sure that the “humans drove the megafauna to extinction” hypothesis is a settled question. My memory tells me that there are competing hypotheses indicating their populations were well into decline prior to human intervention in at least some cases. Either way, I’m not sure how far back into the EEA we can project data from late European Pleistocene and North American Holocene.
In any case, you’ve put together a great post. As I said earlier, I didn’t write this post to say that fat is bad, but to highlight the inconsistencies in the way evolved dietary instincts are discussed in the paleosphere. So… I’m kinda playing devil’s advocate a bit here.
A measured amount of devil's advocacy is important, because it's easy to get complacent as we all congratulate each other for being so darned smart.
And for the record, while I believe Paul Shepard is essentially correct about overkill, I think he also whiffed a few things, like insisting that there was no pre-Clovis occupation of America. I'll most likely go into detail on this subject in the future…but a key point is that assuming that all Paleolithic cultures were the same is like insisting all Neolithic cultures are the same.
As far as heuristics, though, is there any tastable nutrient we have a limited craving for, besides protein? People are perfectly happy to eat fat and carbohydrate (in all its forms, starch and sugar) to obesity and beyond…and the only reason we don't overeat protein is because our bodies can only process a limited amount (200-300g/day, depending on which source you believe.)
I'm not sure that 'cravings' tell us anything except that isolating the tastable part of food from its accompanying nutrients is a bad idea.
JS
Do we really overeat fat because we have an unlimited craving for it? It seems like it's more that we don't have a limit for it (as with protein) and it just goes along for the ride with the carbs.
Neither fat or carbs tastes good in isolation: there's a reason people put cream cheese on their bagels and deep-fry their potatoes, and there's a reason pizza has cheese on it. Even cookies have a big chunk of oil or butter in them (at least the good ones do)…there's a reason the 'fat-free' versions aren't as good as the regular ones.
Even most candy bars have plenty of fat in them, and adults tend to lose their taste for pure sugar candies like lollipops and Pixy Stix.
JS
Fat-free versions aren't as good, but people have been managing to get them down as long as there is enough sugar. And sugar is really a class of its own … especially in liquid form a la soda or other sweetened beverages.
Or maybe the point I'm making is that not that the craving is for fat … but it may be that fat is one hell of a vehicle for carrying sugar.
It’s not a means of proof in a scientific sense. The question is twofold: 1) How much weight should we put in the paleo logical framework absent sufficient scientific proof? 2) How much proof should be required to cause us to deviate from the paleo logical framework with respect to any particular question?
I can’t speak for Mat’s answer on either, but my answers in precise scientific quantification are as follows:
1) A lot.
2) A lot.
I mostly agree. I think we can save ourselves some trouble with a hack and slash job on exactly how far the evolutionary axiom can take us. It is a reasonable hypothesis that we have not adapted to foods that were not consumed during the bulk of hominid evolution so as to make them ideal foods. But can we really say that any particular macronutrient ratio is ideal from looking at the general trends we find in the anthropology? I’m not so sure we can make that leap although many would love to.
While it is demonstrably true that we evolve towards longevity and the general lack of degeneration, it does not follow that we only evolve towards that. We also need survival and reproduction in the short-term and while lack of degeneration certainly helps us extend that breeding window, oftentimes we will display instances of survival adaptation at the cost of longevity. A good example is the mTOR pathway and protein’s role in it. It would confer a survival advantage to just take whatever methionine we get in the diet and stimulate mTOR to replicate our cells so as to keep them new, fresh and ready to serve us at peak efficiency during times of physical exertion. But too much mTOR activity is bad for longevity since it shortens the telomeres, so although Loren Cordain wants us to eat 30% of our calories as steak, eggs and seafood, this may not be conducive to our end goal which is a lack of degeneration. However it might be suitable for an athlete’s goal.
Evolution may be amazing but it is not a god. It is bound by physics and the circumstance of having to use whatever bits and pieces it can get. It happens to be that after a certain point saturated and monounsaturated fats are going to be healthier than carbohydrate and it doesn’t matter how much carbohydrate we got, that’s physics. We have adipose tissue for a reason and I don’t see myself with a glucose sack attached to my ass. It also certainly doesn’t follow that humans are built to run long distances then that is healthy. Physics is the main issue there and there is little evolution can do to cope with the inordinate stress on the body.
So I think that we can only ever form a hypotheses for a type of food item and now necessarily for any macro-nutrient composition. Type of food is an interesting matter and there is actually much more to say for the inclusion of foods than we usually speculate upon. Paleo has a reputation as a “look at all of the foods that I don’t eat” diet. I have argued in the past that it doesn’t follow that an ideal paleo diet has anything more than a little bit of animal brain and marrow and the rest could very well be fruit. I no longer argue this, instead I have a hypotheses of my own.
The human body is frugal and we must sacrifice one feature for another in evolution. We also obtain a great deal of nutrients of all types from the food we eat and so it may be the case that we have “evolved around” particular foods that evolution “knew” we were going to encounter. I think that there is much evidence that we simply lack the machinery to produce optimal amounts of some nutrients, even if we do produce them ourselves. Examples are creatine, phosphatidylserine, various antioxidants, carnitine and others that were just so abundant in the environment that our machinery evolved to not waste resources bothering to make more from other substrate, and if we take those nutrients out of the picture with weird and restrictive diets (vegetarianism, low fat) then we suffer deficiencies of non-essential molecules and hormones. I suppose vitamin A for many people is another one. I can’t make enough vitamin A from beta carotene, I funnel all of my beta carotene off for skin health and stuff without thinking about it and there really is no compromise since my ancestors just had so much of it for so long. I am also skeptical that we can synthesize enough of certain proteins from muscle meat since we consumed a lot of gelatin in the past. There is definite benefit to gelatin no matter what your muscle meat intake is.
So a basis for hypotheses for what we might want to avoid and what we might want to include, although not really the degree to which. That will require some sound empirical evidence.
Food for thought! I wish I was 10 years older with my bio and psyche degrees. These are exciting times for the minds behind that all. I think I’m going to just use Evolutionary Nutrition in the sense that evolutionary psyche uses it. The paleo diet could be described as an evolutionary approach, although in some cases it makes premature postulates.
I take issue with a number of things you said here, firstly your invocation of physics when biology is much more relative. Saying fats are healthier than carbohydrates is not a matter of physics, but a matter of evolved molecular mechanisms in the species in question… certainly this is an issue of biology.
Where do you get these statements about mTOR? While I have seem some (rather shaky) evidence about mTOR and telomerase activity, I can think of much more prudent reasons why chronic activation of mTOR would be bad… such as dying of cancer. Additionally, methionine? While mTOR may be activated by a myriad of amino acids, it is most potently activated by branched chain amino acids- particularly leucine.
Contrary to what you suggest, the human body (or any species) does not have to sacrifice one feature for another in evolution (though certainly this can occur). The human body is frugal? Then why do we have this massive, overly energy requiring brain? New traits arise through variation, and if they give a reproductive advantage the trait will spread. Such new traits do not come, a priori, at the sacrifice of another. Evolution certainly does not 'know' (or speculate, as you seem to imply) what a species will need or encounter in the future… the question is what gives the best reproductive advantage now. In an environment replete with nutritious foods where you consume all the nutrients you need, there is no evolutionary pressure to select for the production of such nutrients
Okay more relevant to biology, then.
I didn't know that about leucine, still does it follow that lots of these mTOR stimulating amino acids is fine just because we encountered them in the past? The issue there only appears to be factual, and I thank you for the correction. The main principle (whether or not supported by that example, heh) is that momentary survival can often undermine longevity.
Sacrificing one feature for another could be restated as that there is always a limited capacity to produce and it has to make compromises. Although it would be great if we could have more beneficial molecules than we do, there is often a limited amount of work we can do even when supplied the proper substrate, or else vegans wouldn't require exogenous creatine to think straight.
Apparently the body doesn't consider all of that energy to the brain to be wasteful, it pays off to put seemingly (although not in actuality) inordinate amounts of energy in the brain
And your last point is correct, that is what I meant but perhaps could have cleaned up my language. We lose the tendency to produce certain amounts of certain things and it never gets re-selected for because we are getting plenty of that through diet. Thus we're going to need to keep eating those things that provide what we are missing. There is just so much focus in the mainstream on essential nutrients and they miss the point that non-essential nutrients can be very important.
Momentary survival can definitely undermine longevity, but you can't have longevity without survival. mTOR is a fascinating protein and is proving to be a lynchpin in a number of molecular pathways, tying together a number of inputs with a variety of downstream effects. It is treacherous to look at such a complicated pathway in an 'all or none' reductionist light. Yes- branched chain amino acids (and other nutrients) lead to the phosphorylation and activation of downstream targets of mTOR, but such activation is transitory, and necessary for a number of physiological processes (muscle growth, for example). While activated, these mechanisms lead to cell growth and proliferation- things we definitely need. When nutrient status is low, inhibition of mTOR promotes autophagy, and plays a vital role in ketogenesis. Both these roles are vital for life- the beauty (and the mTOR pathway is not unique in this) is the transitory nature of the activation and inhibition and its ability to flip the switch from growing to surviving. Yes- a slow steady drip of BCAA (or any nutrient for that matter) causing a chronic activation of mTOR would be bad (indeed- chronic activation of mTOR does lead to cancer), but having it permanently inactivated could arguably be more harmful! It is important to remember that these pathways evolved with us. For the most part, if we live in context with how we evolved, they're going to keep doing their job.
As with the insulin-signaling pathway, we can definitely do things to put ourselves at a disadvantage for longevity by living in a way grossly outside of our evolutionary history. However, I believe we would be ill advised to try and out-smart what biology naturally has going for us by trying to eliminate the need for important pathways in our lives without significant proof as to the advantages of such eliminations. For everything we know about the inner workings of these pathways, there is much more that we do not know. We evolved to be healthy, and these pathways help us stay that way.
My comment about the brain was a counter point to your statement about the body being frugal. There are many things that are blatantly wasteful in our conserved traits- our massive brains being just one example. Granted, these things tend to come as a result of sexual selection (dare I say it, Zahavian signaling), but there are plenty of conserved survival traits that are useless- we just haven’t gotten around to losing those genes yet.
Dear Andrew and Dr. Harris,
I seem not to have clearly articulated what I meant by the "if it ain't broke don't fix it" principle. This is meant to be the least reliable of the concepts I articulated and one that is useful for action or inaction in the face of sufficient scientific uncertainty. Perhaps "if it ain't broke don't fix it" isn't the most useful way to describe it, but what I meant is that ultimately when science can't say anything conclusively about a subject, the sensible approach is to fall back on a logical framework that appears to have a track record of success, and in operating within the uncertainty of that framework (or those frameworks, if they are multiple), one has to follow "what seems to work."
Perhaps "what seems to work" is better than "if it ain't broke don't fix it," as the former doesn't imply inaction.
Taking, for example, the macronutrient ratio, we are faced with the following:
1) There is no strong human experimental evidence for a particular macronutrient ratio, and those studies that exist are in any case all confounded by a number of competing hypotheses (e.g., low-carb vs. gluten-free vs. low-fructose vs. paleo).
2) There is no solid and reliable evidence about macronutrient ratios in the paleolithic era. The best we have is evidence about breadth of food groups (which suggests plenty of animal foods and plant foods, including starches) and isotope studies that can be explained by a number of competing hypotheses.
3) There *is* solid evidence that a wide range of different fat and carbohydrate proportions are consistent with good health, but there is hardly any evidence about whether this is true *within* a population rather than *between* populations, and thus it is possible that some people might do better on one ratio and others with another ratio (it is also possible this is false).
4) Therefore, the most sensible way to deal with the uncertainty is to make a best guess based on available data but ultimately conclude that the ratio that makes you feel best and produces the best overall picture of good health "seems to work."
The alternative would be to fall back on some logical framework by dogmatizing someone's best guess about the macronutrient ratio in the paleolithic, or to interpret current research with great selectivity in order to dogmatize some other logical framework. These would be particularly senseless methods if, in fact, one felt foggy-headed, jittery, couldn't sleep, or had other negative symptoms while following the prescriptions of said logical framework.
What "seems to work" isn't a reliable way of determining truth, but it's necessary to utilize sometimes in order to act in the face of uncertainty.
Chris
Andrew,
Generally, sweet fruits do not supply the highest concentrations of vitamin C on a gram for gram basis. Non-sweet fruits like red peppers far exceed typical fruits, and green vegetables as well.
Vitamin C mg Per 100 g serving
Peppers, red sweet 190
Kale 186
Parsley 172
Collards 152
Peppers, green sweet 128
Cabbage, red 61
Strawberries 59
Papayas 56
Spinach 51
Oranges 50
Cabbage 47
Lemon juice 46
Grapefruit 38
Elderberries 36
Liver, calf 36
Turnips 36
Liver, beef 31
Since humans require only about 10 mg per day to prevent scurvy and 60 mg per day appears to top off the vitamin C pool in most people (pool stops increasing in size, Whitney and Rolfes Understanding Nutrition 6th edition page 325), it is clear that humans have adapted to quite low requirement for vitamin C that certainly does not require a large intake of fruit for satisfaction, and could easily be met by some liver and/or very low carbohydrate greens.
This means our ancestors needed no fruit on a regular basis. Some fresh liver or adrenals, and a small amount of greens eaten directly or recovered from the herbivore's intestines, would abundantly cover all ascorbate needs. IOW our vitamin C requirements do not suggest a high fruit intake among human paleolithic ancestors.
Yes, the deactivation of the gene coding for vitamin C synthesis predates the paleolithic. I didn’t claim this was a paleo development. The deactivation occurred well before the “common ancestor” divergence, and therefore well before the shift to a higher ratio of animal food sources of the paleolithic hominin diet.
I do think it’s accurate to base the hypothesis of the deactivation on high fruit consumption of early primates, but as you point out, that is a different question than the most likely sources for the Homo lineage in the paleolithic.
No upper limit? Glucose can certainly have adverse effects at high doses, as can vitamin D, both "synthesized" by the body.
We have plenty of evidence that high serum glucose levels do damage, even if only postprandial. Glucose is less toxic than fructose, but it also has an upper limit. If not, we wouldn't have a disease where the body responds to toxic levels of glucose by dumping in in the urine: i.e. diabetes
The trouble here seems to me to be in saying that the body can "synthesize" glucose. The body can produce glucose from raw materials in glucogenic amino acids or from glycerol in fats, but it can't make glucose from "scratch," i.e. sunlight, CO2 and H20, that is the job of plants.
The fact that the body produces something does not mean that that thing is nontoxic at any dose. Everything gets toxic as some dose.
@Don
What he is referring to is not some scientific principle, just an observation I once made in thread comments
A heuristic.
linoleic acid and essential amino acids and fructose are either essential or not synthesized by the body
These have pretty defined upper limits for consumption. They make us sick if we eat too much.
LCSFA, glucose, glyccogen (starch) these are internal fuel sources and as such, we have the ability to synthesize them. Apart from the obvious issue of crowding out other nutrients, if our metabolism is intact and caloric intake is balanced, etc. they are not poisons even in large amounts. Compared to the essential agents, they are safer to consume in large amounts.
Synthetic capability = fuel source = safe
Think about if for a minute and don't take it too literally. Now isn't that an interesting observation?
Oh, and I agree with your comment about Vit C and greens. Potatoes are pretty good, too.
Also keep in mind that we're only talking about the fringe scenarios in which the science is undecided. Andrew is suggesting that when you don't have good science, you should use the paleo framework to take action to the best of your ability. I am arguing that before using this framework, asking yourself the question of "does my body make this" and if the answer is yes, and you're healthy, you're probably fine. If the answer is no, we fall back on some evolutionary story to make this decision for us. Using the above heuristic, as I've already pointed out, excludes fructose and linoleic acid while including SFAs and glucose.
I followed the argument with some considerable interest, but ultimately I don't see what the fuss is about.
N=1? Guess what, genetics vary, gut bacteria varies, etc. Individual variation necessitates a respect for individual customization.
This talk about the impossibility of doing controlled self-experimentation is nonsense. It would be equally easy to argue that the supposedly hard science we do is hopelessly flawed, not to mention the purely correlational or anthropological science.
I like all the controversy you guys generate arguing with each other about what constitutes the perfect paleo diet. Because the talking points you raise allows me to better interpret my self-experimentation data and design better regimines. When you don't call each other out, I often have to accept your recommendations as given, without knowing the why. Which sucks when you're wrong.
As for the foolishness of customizing your diet based on how you feel, again I disagree.
Obviously self-perception is problematic. Some of these problems can be corrected with better self-metrics practices. Here's my vitality tracking method: http://www.josephdantes.com/blogs/shorts/?p=827 I've since started tracking ingredients on the same day and page as vitality scores, but otherwise I'm still using it unmodified.
It works quite well at showing cause and effect, and I was able to use it to overturn a major paleo falsehood recently… that potatoes/tubers are the "best" carb source. For people suffering from digestive sensitivity, fried white rice sans husk is actually far better. http://www.josephdantes.com/blogs/shorts/?p=899
And self-perception isn't the only tool one should use. One should also read widely and pay attention to the science. Which is exactly what I did in the above example.
Then it comes down to applying one's intelligence to the situation and desired end and body of knowledge, to make one's plan, and test and iterate it.
At some level this debate is devolving into an attempt to replace general intelligence with methodological rules. That will never work. But you should all keep working together to make each other less wrong.