I wanted to make my previous post on the news about the Neanderthal DNA discovery stand as is and be content to just read articles and discussions on the matter elsewhere, but it turns out that my casual prediction that people wouldn’t be touching it with a hundred foot pole turned out to be a moment of pure clairvoyance. Other than a tiny number of small time local news rags opining sensationalistically and humorously about it (with plenty of caveman puns for good measure), the internet is virtually silent about what is without a doubt the biggest fundamental anthropological discovery that I’ve ever seen in my adult life.

The new fact was added to the Neanderthal entry over at Wikipedia without much fanfare other than some behind the scenes rant which amounted to not much more than how to tip-toe around the word “African”, which I suppose is the culprit in all the aforementioned silence. I’m going into rare rant form for this because I have a bone to pick. Is there anything to be said about the discovery *other* than how we can rehabilitate the political terminology? Is there nothing exciting about the fact that we carry the DNA of a species otherwise known to be extinct? In other words, is there anything at all interesting about science besides how it affirms or denies our social prejudices? I rarely even get to read published research anymore that doesn’t engage in a certain amount of weasel talk if the subject is politically sensitive. That kind of concessionary disposition devalues the research (as well as the ultimate justification for research) by suggesting that researchers need to apologize for reaching necessary conclusions that defy prejudice.

So what’s the great big elephant in the room that nobody seems to want to address? People are different in ways that are more fundamental than culture, and less superficial than skin. Is it really that bad to have to say, this one little admission? Are we all just pretending to celebrate diversity, but then when we see evidence of real diversity we get offended by the suggestion? I stated in my last post that I looked forward to future research expanding on what’s already been uncovered by the Neanderthal genome map, but now I’m getting a bit of a queasy feeling, wondering whether any of that will actually happen. Maybe it’ll get stuffed in a dark vault never to be seen again. Or maybe we’ll only pose bland and uninteresting questions from the data, the results of which will pose no meaningful consequence. I hope none of that is true, but my hope is less vibrant than it was when I first read the study three days ago.

There is of course another, maybe even bigger, elephant in the room though: religion. These kinds of scientific discovery stories are just plain hard to sell to a public that’s largely unwilling to admit that evolution happened, let alone that any such Neanderthal creature ever even existed. At worst this discovery will be blatantly sold by ignorant creationists as evidence that they were really just plain old normal human beings after all. Maybe a lighthearted take on club wielding cavemen and grunting and other such nonsense is the only safe take a news organization *can* express in print.

All in all it seems like this poor beast of a study and the small nugget of truth it conveys is just a no-no among both the enlightened and the superstitious, and that’s an absolute shame on our culture.

So I’ve been on an extended hiatus, but life is life, and life > blog. But a bit of mind blowing news ended up in my inbox today that set my gears in motion. A team led by the department of Evolutionary Genetics at the Max-Planck Institute for Evolutionary Anthropology published the results of a project to sequence the entire Neanderthal genome and compare it to a sample of modern humans. Surprising to many, 1-4% of the genetic material of the human samples outside of sub-Saharan Africa derived from the Neanderthal genome. The widespread existence of the genetic material indicates that the earliest human groups leaving Africa interbred with Neanderthal populations before further diverging throughout Eurasia. Here’s the published research:

• http://www.sciencemag.org/cgi/content/full/328/5979/710

Now most people, even those excited and interested by the news, aren’t going to touch it with a hundred foot pole because there are just too many unsettling conclusions and potential political consequences that might result from the now necessary admission that non-superficial variation exists among modern humans, one of those conclusions touching on another post I made recently. I won’t beat that one to death, but suffice it to say that this new revelation nicely bolsters the argument that healthy dietary patterns have a necessary ancestral component.

Is a 1-4% genetic contribution from a related hominin species anything to get worked up about beyond simple amusement? It depends on exactly *what* was contributed of course, but to put it in perspective it’s also well known the degree to which we share genetic relation to the chimpanzee (which  incidentally was used as a reference genome in the study) and our respective dietary patterns, and the physical adaptations that underlie those patterns, are not in any way merely superficial.

Besides the fact that it’s incredibly cool to know that I’m part Neanderthal, not much else can be said about this story, but I assume that since we now have a complete Neanderthal genome map and some incredible upfront results to point to, that subsequent studies will be able to ask more and more specific questions about that relationship, and I most definitely look forward to reading, pondering and writing on the results of those studies.

I recently alluded in a comment to an upcoming post that’s in the works regarding my nutritional philosophy, but since it’s becoming something of a mini-dissertation, I thought I could roll something really quickly in the meantime that’s actually a component of my current research on the matter. This is that…

During one of my feverish bouts of skim research I recently combed out an abstract to an article titled “What do Stable Isotopes tell us about Hominid Dietary and Ecological Niches in the Pliocene?”, from the International Journal of Osteoarchaeology, which synthesizes the results of carbon and oxygen isotope analyses from a wide variety of Pliocene/Pleistocene deposits in South Africa for hominids and related fauna. The full article can be accessed here at no cost:

http://www3.interscience.wiley.com/journal/102528305/abstract

The purpose of the study was to characterize carbon isotope values that distinguish between forest and grassland consumption patterns, as well as distinguishing oxygen isotope values that are widely understood to characterize carnivorous consumption patterns, and compare those values against data collected from the isotope analyses of a variety of fossilized bone samples collected from the aforementioned deposits.

The study forwarded two major conclusions:

• All of the fossil sample groups analyzed showed significant reliance on foods originating from grasslands, with the caveat that it would be impossible to distinguish whether the isotopes were contributed by the consumption of animals that ate the grass, or from the grass itself. Dental wear analysis however showed none of the characteristic patterns related to grass consumption.
• Oxygen isotope values for all sample groups were consistent with carnivore values, but with the caveat that the mechanism for oxygen isotope deposits was poorly understood.

These conclusions are in fact at odds with previous analyses based on classical sources for dietary modeling, including craniodental anatomy, dental wear, tool association and, of course, educated guesstimation. Not coincidentally or insignificantly it also moves back the hominid transition to grassland lifestyles by about a million years from previous estimates based on environmental models. The authors were certainly not overreaching in their conclusions beyond the grassland transition hypothesis due to the existence of alternative explanations for each of the values, but it must be said that when multiple threads of data intersect on the same conclusion, that conclusion is likely a pretty safe bet. All early hominids deriving from Australopithicene lines were significantly predating/scavenging on grass consumers. To what these values don’t enlighten us in regard to the forest dwelling component of their diet, I would venture comfortably to say that meat consumption was equally significant if it can be assumed that consumption patterns are illustrative of behavioral patterns.

There’s a moral to this story (blog post) of course: even our very earliest bipedal ancestors weren’t merely scraping by on leaves, roots, occasional fruits and fortuitous carcasses, distracted by fear or incapacity, but were actively carnivorous to a very significant degree, which implies success in predation and in competition with other grassland predators. Every time we move the goal post back on when exactly it was that we were soft, weak and vulnerable, we find that the post needs to be moved back even further. Maybe the reason is that we actually never were any of those things. That’s food for *my* thoughts anyway.

The Question

Alot is being made lately in the blogosphere about whether humans were designed to be long distance endurance runners, and since it and its implications are intimately associated with a recent post I made, I thought it would be in good form to explore the whole venture and come down with a verdict on one of the most interesting questions currently on the table: are we really born to run?

Right off the bat the question as presented is pretty tricky. The word “run” has limited value in describing movement because it connotes a wildly differing set of locomotive forms among which the only thing shared in common is the fact that they all exceed the pace of “walk”. By and large I would say most of the people I know intuit the term to mean something like jogging, while a smaller, but still substantial, group immediately imagine it to mean sprinting. Below jogging there’s a pace that I once read in a book long ago described comically as “chicken walking” owing to the appearance of the feet barely getting off the ground. There’s also a wide range of speeds that register between jogging and full out sprinting-to-capacity, but they generally don’t have distinguishing terminology. The problem is that graduating up the speed ladder isn’t a simple matter of increasing energy input to get a higher output. The biomechanics of locomotion vary enormously as pace increases, engaging connective tissues at different angles with different muscle fiber groupings and using different energy cycles. The complexity is so enormous that it can’t be described with simple force diagrams in two dimensions. Once again…fodder for another post.

So how are we to understand the question? The frequent term I see being used in reference to that question is “endurance running”, which basically means to run at a pace that’s physically sustainable over long periods of time. That’s no more enlightening though because it covers everything from chicken walking to some seriously fast jogging, depending on the individual, but people sort of visualize the term to mean something like a marathon pace (which is on average between 5-6 miles/hour). For the sake of utility I’ll take that figure to be the referent and move forward.

The Evidence

There are two  major sources of inspiration for the notion that we have a unique evolutionary adaptation to moderate paced locomotion over great distances and are as follows:

• The scholarly works of Daniel Lieberman and colleagues on a number of questions related to the human biomechanics and physiology of bipedalism and, of particular interest, publications on the evolutionary case for endurance running (The First Humans – Origin and Early Evolution of the Genus Homo. PDF file).
• Surviving cultures that continue to practice persistence hunting techniques in the modern world, and specifically this video which has become the stuff of legend for people on the pro side of the natural human endurance runner theory.

I don’t think that the evidence when taken together makes the case the way most people would have it. The problem is not that the evidence presented is flawed, and are in fact outstanding, but rather that the conclusions of lay readers don’t typically follow from the sources.  The biomechanics of running are soundly presented in the study I linked, as are the evolutionary assumptions for related physical adaptations. Hairlessness, prolific sweat gland development, energy storing tendons…it’s all beautifully argued. But in what is says about capacity, it says nothing about necessity. It says nothing about the effect that a chronic regimen of running at great length has on the human body over time, only that we’re adaptively capable of doing so.

And modern hunter-gatherers really do still persistence hunt, but the scientific literature on the subject makes strangely vague references to hunters “running down” prey, or “running them to exhaustion”, leaving it entirely to the imagination of the reader as to what that might mean. And the imagination of the reader so far seems to not deviate much from “marathon”. In fact, the kind of movement that occurs in a persistence hunt is a highly fluctuating pattern of short sprinting bursts, very long walking-paced tracking sessions and moderate bouts of jogging-paced movement to apply pressure to weary prey to avoid shade. Each hunt is different and involves variation from the basic formula, but what it never amounts to is a hunter running off toward an animal at 6 miles per hour until the latter passes out. The Attenborough video shows all of the basic elements, but unintentionally misleads the viewer by cutting out literal hours of the boring walking, trotting, standing around talking and thinking, that happened between punctuated instances of action.

The Conclusion

The strict answer is obviously yes, we were born to run, or else we wouldn’t physically be capable to do so. But in taking the whole range of it we have to say we were born to jog, born to sprint, born to trot and chicken-walk and the whole rest of the lot. In short, we were born to “move”. Experiencing the full range of human capacity is most definitely a good thing. What there still isn’t any evidence for is that we were born to do any of it repetitively and chronically.

The next entry in a series of blog posts you could informally refer to as “tackling the most controversial topics of the Paleo nutrition genre”, I felt like I just had to get the question of carbohydrates out of the way. I’ll deal with other controversial sub-arguments related to sourcing carbs each in their own respect some time down the road, but for now I want to focus on the big stuff.

The first point I want to make to provide some context, and a bit of a value judgment, is that too many proponents of Paleo-like diets have a funny tendency to market the thing upfront by selling you on the idea of all those wholesome fruits and vegetables you’re going to eat, but then slowly pull the carpet out from under you. First goes the fruit, then the starchy vegetables and then hey, you already made it that far so what’s the point of eating the leafy greens or the rest of the lot? Basically it’s a bate and switch operation. And who can blame them? Paleo is pretty close to carnivory as it is, so you can’t help that carnivores are going to come on board at a pretty high rate, and a public that’s well conditioned to think of fruits and vegetables as paragons of health and longevity is going to be more sweetly influenced by their emphasis.

That’s not to say that there isn’t an opposing current meeting them in the middle with a new wave of meat-and-potatoes Paleoism. Altogether it’s just a particularly advantageous angle from which we get to see with high clarity that the term “Paleo” has been stretched to its absolute limit…the very last fiber of it’s last thread is taught and on the verge of snapping. In response there’s a new and rising nomenclature developing to describe these sub-categories within the genre, which I’m not going to get into because it amounts more to parody than enlightenment. Suffice it to say that there’s a healthy tide of completely normal and expected fragment occurring in Paleo land that’s entirely the result (or fault if you prefer) of its very success. Too many people in the tribe means the tribe has to split, and that’s pretty much what you’ve got.

So yeah, about those carbs…before I draw my own particular line in the sand I want to lay out to bear my personal eating habits and general food philosophy so you can neatly file me into a pre-determined category and subsequently feel at ease. I’m a long time carnivore, a true full on keto guy. I literally eat nothing but animal flesh, organs, eggs, marrow and bone broths. I’m a little bit Neolithic on the side (shhh, don’t tell Paleo, she’s my true love) because I eat a not insignificant amount of cheese and love butter and cream, and I also indulge every so often on some avocados. I have the odd vegetable here and there, but if so it’s something energy poor and micro-nutrient rich. I don’t deny my family the comforts of the fruits and vegetables *they* desire and I’m a fairly accomplished home chef, so I’m no stranger to preparing food from many sources.

Do I eat like this because I hate carbs? Not in the least. I’ve simply found my best fit, my environmental and evolutionary niche. After years of experimenting from a starting position of classic Paleo, I’ve come to find that I perform and feel better on a carnivorous diet that’s heavy on animal fat. I may be a lipophile, but I’m not a carbophobe. So why are carbs getting such a bad rap? I really don’t know, but I’ll throw out some guesses:

• Aversion Therapy – after a lifetime of having carbs shoved down their faces, some people feel liberated by the freedom Paleo afforded them and now just have a natural revulsion to the substance, regardless of actual health implications.
• Science (AKA Gary Taubes) – there’s a new wave of basic research and science journalism that’s helped to fuel the entire class of low(er) carb eating programs that implicate the role of carbohydrates and a disordered insulin cycle in the prevalence of obesity and related ailments.
• Wolf Men – alot of people out there are like me and really are just animal consumers by nature, but in a proselytic ecstasy have unwisely extrapolated their own proclivities to all of humanity in general.

Some of the most vicious e-wars I’ve witnessed in the hallowed online battlefields (otherwise known as the blog comment areas) have been related to nothing more than how many carbs a person needs to eat compared to how many carbs the opponent *wants* to eat, and seemingly invariably ends with an uneasy stalemate of defensive projection, waiting to erupt again another day in response to some other vaguely related post. My position officially is that the vitality and health that a person feels on their own eating plan is personal to them, to their genetics, to their inclinations and to their own requirements. To be an honest proponent of Paleo it’s important, for both reasonability and credibility, to embrace the full range of natural human eating patterns that fall under the moniker and to treat them as equally valid expressions of healthful eating within our species. I regard the carbophiles, the lipophiles and everyone in between with equal enthusiasm. We may be on different teams, but we’re still all playing in the same league.

I’ve been involved in numerous conversations and debates lately, both online and in the ordinary world, about how much (if any) dietary adaptation has taken place since our early days as modern humans which was roughly some 200,000 years ago. The point of asking is of course to determine whether a natural and proper diet for any given individual is somehow related to their own ancestry, since our species has long since been diverted from our original cradle in eastern and southern Africa. My verdict on the case: yes we are variously adapted and perhaps even significantly. Here’s my argument:

Humans left Africa quite a long time ago. They of course didn’t leave all at once, but left in random groups and in varying directions for various reasons over the course of time. Some groups outside of Africa are almost as old as the human species itself, but major groups had left Africa early enough to make it to China by nearly 70,000 years ago, and to Australia by about 60,000 years ago. Europe was entered by modern humans probably 50,000 years ago and they had completely displaced Neanderthal by 10,000-20,000 years later. For a species that’s estimated to be about 200,000 years old, those are some very significant proportions of time spent in genetic and environmental isolation. It would be silly on just that basis alone to assume that very little to no dietary adaptation has occurred in the same space of time.

The plainly observable adaptive traits among various branches of the human species related to ecological variance presuppose real underlying *physiological* adaptations. The requirement for sunlight induced vitamin D synthesis, which is widely believed to be the selective pressure for skin pigment variation, for instance, doesn’t only effect the superficial aspect but creates a cascade of necessary adaptations one way or the other. The northern dwelling European of bygone eras didn’t simply adapt to make more vitamin D with less sunlight, they needed to go days, weeks and months without the benefit of sunlight altogether, which increased their requirement for purely dietary sources of the vitamin. It’s not wildly speculative to assume that this has resulted in genetic level adaptations related to the *entire* complex of physiological processes that involve vitamin D’s role in the body. Nor would it be wildly speculative to extrapolate the case of vitamin D to any other known and unknown instances of environmental pressures that have shaped modern humans into their many splendored forms.

There is a wide variation in the *observed* dietary habits of healthful modern hunter-gatherers. Much has been made lately about the health and vigor of the Kitavans, a group of modern semi-hunter-gatherer people whose diet is composed by as much as 70% from local carbohydrate sources, and yet seem to show the same resistance to civilization diseases as other HG groups around the world that consume very little in the way of carbs. They are becoming the cult heroes of the carbophile end of the “return to your roots” spectrum in the same way that the Inuit have been the poster culture for the lipophiles. But is this evidence that you can just select any HG peoples’ diet randomly from a hat and just presume to thrive on it regardless of personal relation, or more so that a few isolated groups have simply adapted physiologically out of *necessity* to the unusual conditions of their niche environments? The latter seems entirely more likely, especially given the strength of the clinical evidence that’s emerged to corroborate the insulin cycle model for obesity among westerners. It seems like nonsense to think you could feed the average westerner a diet of 70% yams and get anything other than disaster.

All in all, whether and to what extent our personal ancestry conditions the requirements for *optimal* health and body composition, I will always concede that we can each thrive very well on the diet of our common African ancestors, so when there’s doubt or a lack of inclination to experiment with your nutrition, you can’t go wrong with a prescription to the standard savanna diet of the original human from which we all descended.

Blogging is pretty easy going early on because I have a seemingly endless supply of fresh topical material from which to choose. No doubt I’ll have run the gamut before the well goes dry and I’m off to other endeavors. Today’s free association session revolves around something actually pretty new to me: barefooting. I was introduced to the whole concept for the first time, like many things I hadn’t previously conceptualized as “paleo” facets of modern life, over at Mark’s Daily Apple. Since then, going barefoot has always been something of a project I keep in the back of my mind to execute at some shadowy unknown future date. It sounds like a great thing to do, a natural thing to do, a Paleo thing to do…but I just hadn’t crossed the threshold toward “do”. That is until I saw a video of a guy known as Barefoot Ted (Ted McDonald) giving an hour long talk at Google’s office in Kirkland, WA.

As you might imagine from his nickname, he’s a barefooting enthusiast and, very importantly, he’s a barefoot long distance running athlete who’s proven through great personal effort the efficacy of barefooting and the value of the amazingly functional mechanics of the human foot, in all of their natural glory. I had read alot of commentary about this guy, his story, his ideas (and the video posted above) for a while because I have a nasty habit of addressing knowledge from context far too often instead of digging into the sources. This is sort of a time efficiency maximizer and lets me wade through alot more material more quickly, but if I hadn’t taken the time to watch this video (and you should too), I would have missed a diamond. It would be an understatement to say that his talking style is mesmerizing. One hour felt like fifteen minutes and by the end of it I was 100% sold that modern shoes are basically casts, splints for your feet that do nothing but rob you of your natural physical development, and that I need to get the hell out of them.

One of the issues that stands in the way of widespread acceptance of this idea is the entirely understandable fear of social perception. It’s basically a matter of how strong we are at dismissing our innate concerns about the internal content of other peoples’ minds. After all, those once-ubiquitous “No Shirt, No Shoes, No Service” signs that are still scattered around aren’t there to protect your good health. The answer to our problems it seems is the growing popularity of what has to be termed “barefoot shoes” (yes, an oxymoron of wonderful hilarity). The most popular example of the genre seems to be Vibram Five Fingers:

These products ostensibly have the purpose of allowing your feet full articulation while protecting it from puncture and abrasion, but in all honesty seem to mostly function as a way to appear to be wearing shoes while saying you’re going barefoot. And as Barefoot Ted waxes so eloquently, people need a purchasable solution. I can’t deny the appeal of these things on all accounts, and they’re on my short list to be perfectly honest, but in the meantime I’m conditioning my feet in their natural unshod state to get back in touch with the missing proprioception I’ve gone without for nearly 33 years worth of a lifetime. Around the house: barefoot. Yard work: barefoot. Weight training: barefoot. Sprint tag in the back yard: barefoot. Spring time is here in California and I’m looking forward to a great season of camping, hiking, fishing, and generally spending alot of time outdoors in a pair of Five Fingers.

So, true to my word, I’m going to wax random and spew a stream of consciousness about one of my long time favorite subjects: dreaming. At one point in my life, during one of my “spiritual” phases (I’ve since come to the conclusion that life is *itself* the the spiritual phase, but that’s for another post at another time), I became quite adept at the fine art of lucid dreaming, which basically means taking partial or total conscious control of your dream environment. It’s not as hard as it sounds, and the details of doing so can readily be found on the internet, but I say all that to say this: the dream world is absolutely one of the most “primal” places we spend time in the modern world. To what survival advantage or physiological process the act of dreaming serves is still up for debate, but as an adaptation it’s pretty popular because we share this phenomenon extensively with other animals, but what we do know about dreams is pretty interesting in itself. Most dreams center on anxiety of some kind, whether social or physical. Mine have a tendency to focus on sprinting and avoiding obstacles while either chasing things or running from dangers (which comically have included over the years: doglike monsters, the police, alien spaceships, Freddy Krueger).

This is where the Paleo link comes in: we do alot of things in our dreams that we don’t do in our regular, polite lives, and many of them are very natural things to do. Sprinting is something I do constantly in my dreams, but only occasionally in the real world, and even then only in predesignated places that make the act unlikely to be perceived as a post-robbery get away run, for which I’m all dressed for the occasion in recognizable athletic attire. Sprinting is one the best feelings in the world, it’s like screaming at the top of your lungs or smashing some article of technology that never works when you need it to. You just feel like you’ve been set free from the cage and the sky is the limit. It’s just not something you do in polite society because polite society isn’t intense. It’s regulated and predictable and nothing is too fast or too loud. But you want to sprint, you’re body wants to sprint and your dream mind knows you want to sprint. The dream world is a place of freedom where all of our truly human impulses are explored and given expression.

But oddly enough, even dreaming is sort of an impolite thing to do. People don’t lightly discuss the content of their dreams with others, fearing that we’re letting out little secrets about our inner minds that we’d rather not share. If the world is nice and neat and polite, then our private mental space should be as well. Alot of people I know don’t recall dreams often, and don’t really want to. All in all it’s just some surreal interruption of the sleep that’s going to see them through to another day of well structured living. I guess there’s a case then for why hunter-gatherers are so good at recalling dreams and incorporate their dream experiences openly into the fabric of their social structure. Dreaming is a natural and integrative process in  life, which links us to deeper levels of our innate humanity…those deep layers that we spend a lifetime burying under heaps and gobs of order and gentility.

Are We Really Supposed to Look Jacked?

As I was writing up my last post, it most definitely didn’t escape my attention that many many people that have arrived at the Paleo diet/lifestyle have done so in order to lose weight, to get healthy and to feel good about themselves, and that emphasis on being lean and ripped might serve as an impediment to people that are barely holding on to sanity and hope in their journeys. I nearly included a section at the time on the matter, but I wanted to deal with it as its own topic because it’s such an important one. I certainly don’t emphasize that perspective in my daily life, especially when dealing with friends and acquaintances that are on that very same journey. But I think that the truth is always a good place to start, and there’s absolutely no reason that we can’t be honest about the basic facts at hand and also be compassionate, patient and encouraging all at the same time.

It’s important to realize that most of us live and work in physical and social environments that are conducive to weight gain, and altogether inconducive to fitness, so it’s not surprising that most of us are also not fit in the way that our ancestors were fit. If you’ve just begun a journey of weight loss, and have alot of work ahead of you, imagining your ancestors to be super-athletes with beach body physiques shouldn’t be a discouraging event, it should be an inspiration to know that that very same toned, muscular super athlete is inside of you waiting to be revealed. It’s not some unattainable goal only meant for elite fitness gurus, it’s your own personal birthright and it’s up to you to come into your fortune.

The human form is as graceful, functional and beautiful as the leopard on the hunt, and every bit as inspiring. I take personal inspiration from my ancestors by embracing their strength, their confidence and their grace, and abandoning all of the false messages of weakness, hopelessness and vulnerability to which we are endlessly subjected.

The question: are we supposed to be ripped, jacked toned specimens of abdominal perfection? Is this really a good representation of our Paleolithic ancestors?

I’ve been wanting to write on this subject for quite a while and I had it squarely in mind when I started this blog, but the effort I wanted to put into it was substantial, so it had to wait until my newborn settled down a bit. I had carried on a fairly lengthy exchange with someone over at Mark’s Daily Apple in one of the post discussions that Mark picked up on and created an entire post to explore the topic. My conclusion was that our Paleolithic ancestors (and by consequence us) *were* in fact adapted to carry very little body fat and to maintain strong, dense, functional muscularity. Some of the premises in support are intuitive, some comparative and some consult direct evidence. I’ll structure my argument here as a series of responses to opposing arguments:

Don’t humans have the ability to store fat so we can survive lean months and periods of famine? – Possibly, but it seems like it has a much more prolific role as a small buffer to our energy needs during daily and weekly cycles of feasting and resting. Other high order carnivorous species with which we shared our environment (lions, hyenas, wild dogs) also have the ability to store great quantities of fat, as evidenced by captivity and domestication scenarios, yet never seem to in the wild. So apparently seasonal blubber for land based predators in temperate climate conditions offers no species level survival benefit. A cache of fat on the body only serves to slow down a predator, decrease their agility and reduce their overall functionality. A little fat also goes a pretty long way, considering that a pound of it provides 3500 calories, 10 lbs of it (on an average male human this is perhaps 6% of total mass) provides enough energy to eat absolutely nothing for the modern human for maybe 20 days, not including the muscle tissue that would also be metabolized to meet the functional protein requirements of organs, which is often 50% of total weight lost in famine. A mere 6% body fat could earn you as much as 40 days of life without food, so even a very lean human is endowed with substantial reserves as is.

It seems like people have a very easy time putting on fat, and a very hard time getting it off…doesn’t that mean that our physiology makes that the “normal” condition? – It doesn’t if our surviving  hunter-gatherer brethren of the modern world are in any way a reasonable analogue to what Paleo man looked like, and I have a strong suspicion that they are. These people are invariably low on body fat, even as they’re well nourished. I know from personal experience that once you’re body is lean, it’s almost impossible to become fat on a natural, Paleolithic style human diet with a modicum of physical activity. How much more so that would have been for Paleo people who had truly physically demanding lifestyles? Here are their most representative descendants:

Australia's Aboriginal hunter-gatherers, prior to contact with western diets, display low body fat and high natural musculature.

!Kung San hunter-gatherers, though of realtively gracile appearance and slighter musculature, also show very low natural body fat.

So maybe there’s a case for low body fat, but don’t all these male fitness types have way too much muscle? – Not even close. The archaeological record tells us that Paleo era people had large tendon attachments, indicating thick, well developed musculature which no doubt came in handy during the rigors of hunting and generally surviving the harsh environment of the time. It must be noted that not all surviving hunter-gatherers are so well muscled as their/our Paleo ancestors, but there has been alot of adaptation between then and now. Technology has improved and made beefy muscles less relevant to survival for many of them. The muscle mass that each person carries at natural equilibrium is going to be a matter of genetics, so there are many different looks that qualify as natural, but none of them are fat.

One point to which there is no argument is that people *want* to look lean, fit, muscular (in each their own way), functional and well proportioned. People are attracted to people that look like this universally and as attraction follows form, and form follows function, it’s pretty damned likely that the proper human form is the one to which we are hardwired to find appealing.

A caveat: being a man, I have seemingly little insight into how many of my ramblings relate to the female form and female function. I apologize for that, but also have no particularly good remedy for the situation either. Fortunately there are many women out there in this genre of blogging that have some good insight to share on their own behalf, and I certainly welcome their input to help round out the picture.

IntroductionComparison with other carnivorous species

Comparison with existing hunter-gatherers

Superimposition of modern hunter-gatherers with skeletal muscle mass of Paleo hominins

Euro-grok (to borrow a meme from Mark Sisson)

Phsycial appeal: attraction follows form, form follows function