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Archive for February, 2012

If I were to ask my fellow med student how natural selection might impact the everyday business of medicine on the floors, I’d probably get a few puzzled looks.  The last time most of my classmates saw the word ‘evolution’ in an academic setting was probably in a basic biology class, which for some might have been as far back as High School.  Med students are quick on the uptake, however, and anyone who has spent any length of time on the floors (or listening to over-hyped news anchors on the 5 o’clock news) has heard of the growing number of antibiotic-resistant bacteria we’re breeding in the hospitals.  There we have it- evolution in action!  Push a little further and someone might remember that being heterozygous for sickle-cell offers some benefit when infected with malaria, so we see sickle-cell disease most frequently in those of sub-Saharan decent.  After that- crickets…

For those of us that spend a bit (ok a lot) more time than most musing about how natural selection applies to everything (it does- I’ll write about that sometime soon), it’s sometimes hard to explain to others why thinking about human health from an evolutionary perspective is the smartest place to start.  After a while it just seems obvious.  When you’ve spent enough time talking to those who also embrace an evolutionary approach to health, you start to banter about the details while forgetting that there are many people out there who haven’t yet seen the big picture.

The big picture- for those that missed it- is that our hunter-gatherer ancestors evolved to fit a very different environment from the one we live in today.  The details of how our ancestors lived are being hashed out by archeologists and anthropologists, but it is obvious to everyone that the modern culture in which most of us live is very different from that which our great-grandparents lived in, let alone the one our pre-agrarian ancestors enjoyed.  Others have spent a lot of time and effort exploring the different aspects of life from an evolutionary perspective- nutrition, exercise, sleep, social interactions- they all matter.  I don’t want to rehash these subjects on a broad-basis here as I think others have already done that job very well.  With time, I will explore some aspects of these elements, but for those that are looking for more on these general topics now, I would suggest the following links.

In the paleo-sphere, there is the occasional dust-up about how useful it is to ponder ‘What would Grok do?’.  Just because our ancestors did something does not mean it is something that we need to do now.  Equally, just because something is modern or a product of civilization does not mean it should be eschewed.  What an evolutionary based perspective on health offers is a paradigm which we can hark back to when trying to understand human health (or the lack there of) in the modern world.  As Andrew, of the wonderfully thought provoking blog Evolvify once said “paleo is a logical framework applied to modern humans, not a historical reenactment.”.

While there is a growing community of individuals who embrace paleo concepts in their personal lives, the idea of evolutionary based medicine has yet to take hold in the medical community.  While there are select situations that are attributed to selective pressures- such as bacterial resistance and the occasional genetic mutation such as sickle-cell, a much wider approach- the idea that natural selection applies to EVERYTHING- is very much lacking in modern medicine.  This is unfortunate, as an evolutionary perspective is increasingly necessary for understanding the complex and pervasive chronic diseases that are becoming all too common.  Specific diseases have specific causes, which once identified can be researched, understood, and hopefully targeted with specific therapy.  A good example of this is Cystic Fibrosis, a condition in which an individual inherits two faulty copies of a gene responsible for transporting chloride ions across membranes.  This condition has a clear cause, which is now well understood.  While treatment of this disease is not easy, great progress has been made.  Similarly, cancers that have specific causes, such as cervical cancer caused by Human Papiloma Virus, have been identified and prevented by diminishing exposure to (or immunization against) the problematic factor.  Alas, most chronic conditions, such as diabetes, hypertension, dyslipidemia, and many autoimmune conditions as well as a number of developmental conditions such as ADHD and autism, have not been traced back to a single cause.  These conditions are multifactorial, and unlike conditions caused by a genetic mutation or infection, the manner in which the condition arises is different from individual to individual.

Since the nebulous and chronic conditions mentioned above do not have a specific cause (an identifiable gene, infection, or exposure) – they do not have a specific cure.  Much research has been conducted (at great expense of time and resources) to understand these conditions, yet the returns on such investments have been limited.  While some measurements of disease can be altered with pharmaceuticals or lifestyle therapies, there is no single factor that can be targeted.  These conditions do not share a single, specific cause.  Broadly, however, these conditions are the result of humans living outside the limits of their body- limits set by thousands of years of evolution.

Because ‘diseases of civilization’ are caused by the intersection of many different factors, they remain resistant to classical scientific and epidemiological techniques.  Trying to find a single cause for hypertension, for example, is about as easy as nailing jello to the wall.  There is no single cause- no one nail- that can pin this problem.  Instead we need a framework to better hold and view the issue.  An evolutionary perspective offers such a framework – it also offers the way to prevent and treat these diseases.

But what if we could find a single way to cure these nebulous disorders… Should we?  If there was a pill that would treat (effectively and completely, with no side effects) these conditions, would it be better to continue living as we are- outside of our limits- but without the nasty side effects?  I tend to think that’s a decision best left to each individual, but I offer this corollary (by way of an anecdote).  I don’t take a multivitamin (I do take Vitamin D during the winter, but that’s a story for another post), as I think that an appropriate diet of real whole foods that I am adapted to eat provides me with everything a multivitamin would provide… and then some.  It’s the second part ‘and then some’ that I think is important to think about.  A multivitamin contains all the vitamins and minerals currently accepted as necessary (or beneficial), but it lacks all the other thing that whole foods contain that we have yet to study and identify that are probably also beneficial for our overall health.  In the same vein- while we may be able to control hypertension and diabetes with medication, preventing these conditions with an appropriate lifestyle offers control of the condition without side-effects from medication, with the added bonus that living within your evolutionary limits likely also offers other benefits that we have not yet fully elucidated.

A pill may fix your hypertension or your blood glucose, but chances are there are still things in your life that are out of whack.  It’s not uncommon to hear someone say ‘I went paleo to lose weight, and my skin cleared up.  Or ‘I went paleo because of my high blood pressure and my joint pain went away”.  It is all connected- and treating the body holistically, instead of treating a symptom, leads to improvements beyond the reduction of a single marker of disease.

When talking about evolutionary health, it’s very easy to slip into something that sounds like a ‘Just So Story’.  It is true that we only have limited clues about the environment in which our ancestors lived.  Geology, archeology, anthropology, biology- particularly genetic analysis- can all offer evidence to help us better understand our evolutionary past, but there is still a lot we don’t know.  What is obvious, however, is that as much as we may fret about the details of the conditions under which our species evolved, it is important to understand the basics.  If eating meats, vegetables, tubers and fruits, moving frequently, and sleeping well is the stuff of ‘Just So Stories’, I’ll take that any day over the modern apocalyptic sci-fi tales of lipid panels for kids, pizza as a vegetable, nutrition from pills and energy from drinks.

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The relevant factors…

I’m going to guess that many of those reading this are friends and family who feel obligated to feign a bit of interest in my attempt at blogging.  On the off chance that you don’t know me (or would like to know a bit more about me and what I hope to accomplish here), here are some of the relevant factors…

I’m an MD/PhD student who just started the clinical portion of my degree.  That means I’ve completed my undergraduate (a B.S. in biochemistry), the first two “pre-clinical” years of med school, my PhD (in pharmacology and physiology, specifically exploring the effects of chronic alcohol consumption on signal transduction in the liver (No, I didn’t study myself.  Yes, at times I probably could have.)), and am now on the floors learning how to put all this into action in the clinical setting.

An MD/PhD degree is an interesting combination of medicine and science, and many medical types will admit that “mud phuds”, as we are sometimes known, are a bit of an odd bunch.  Perhaps more interested in the basic sciences than most medical students and doctors, perhaps a bit more people-oriented than your typical lab type, we’re a mix of the academic and the clinical world.  We are also, unfailingly, rather nerdy.

The phrase ‘bench-top to bed-side’ is often used to describe the role of an MD/PhD.  ‘Physician scientist’ is another popular phrase.  In my writing I hope to take a slightly broader perspective on this role- hence the ‘Principle into Practice’ moniker.  While I like to look at basic research, and plan to explore and share interesting primary literature (scientific journal articles), I hope to be able to always hark back to basic principles that are applicable in day-to-day life.  Furthermore, as a budding physician, I hope to explore how these principles are applicable to medical practice.

I’m only at the start of my medical clerkships- the process by which I will expand my clinical knowledge and also get a flavor of multiple medical disciplines so that I can chose what avenue of medicine I wish to pursue.  MD/PhDs frequently (though not exclusively) opt to venture into some of the more academic and competitive specialties.  While I may well change my interests in the next year and a half, at this point I am most interested in primary care, most specifically in preventative medicine.

I want to make it clear here and now that I am in awe of what we are able to accomplish with modern medicine.  Some degree of illness and injury are unavoidable, and when these things strike, I am very glad we have the medical arsenal (of knowledge, techniques, and pharmaceuticals) to treat and manage these conditions.  That being said- many of the conditions physicians currently treat are wholly preventable- that is where my interests lie.  Furthermore, understanding the mechanisms by which chronic disease occurs, and exploring the evolutionary basis of these mechanisms, is a bit of nerdish fun.

So I suppose I should close with that warning.  In my writing I plan to explore and promote basic principles that are practical for everyday life and for the practice of medicine.  I tend to enjoy distilling things down to basics when possible, but I also can’t help but geek out a bit on the history, biochemistry, and general fun-factor of life… I hope you’ll join me for the ride!

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…is another paleo blogger.

Actually- I don’t think that’s the case, but here I am.  What the world might need, however, is a few more ‘paleo’-minded doctors, and I am one of those in the making.

Many of my friends (and people that might actually read this) are familiar with the term ‘paleo’, though as it means different things to different people it’s only fair that I explain my interpretation of the word.  To be clear, I don’t use the term ‘paleo’ as a clear-cut definition of a specific diet, lifestyle, or perspective, but I think it is a useful term for describing a general set of principles that are loosely based on the evolutionary history of humans.

Like all species, humans evolved to thrive.  Like it or not, you are the result of millions of years of evolution.  While some species live in very precise niches in very particular circumstances (think, for example, of the thermophilic bacteria of the deep sea hyperthermal vents, or the limited diet of the eucalypt eating koala), the human species has evolved to thrive in a variety of environments and on diverse diets.  What has become clear, however, especially to those that pay attention to epidemiological trends or to those that marvel at the expanding waist lines, increased health costs, and mountains of prescription and over-the-counter drugs so many have come to rely on, is that humans are not ‘thriving’ as one might hope and expect in our modern world.

On a whole, the world in which humans evolved has not changed dramatically in the last couple of hundred years, but the environments in which many humans live-namely the civilizations which we have developed for ourselves- are incredibly different (there are certainly people living in traditional cultures, but they’re unlikely to be reading this on the internet.  If you’re reading this, this applies to you).  For hundreds of thousands of years, humans were hunters and gatherers.  Ten thousand years ago humans adopted agriculture.  The industrial revolution occurred a few hundred years ago, and the scale and rate of change of civilization has accelerated from there.

Darwin came to the theory of evolution after reading Principles of Geology by Charles Lyell while voyaging on The Beagle.  Lyell was a geologist who advocated the idea of uniformitarianism- the concept that the earth was slowly shaped by continuous forces over a long period of time that are still occurring today.  This was in contrast to catasrophism, which dictated the environment was shaped by a number of large, catastrophic events (in consonance with biblical stories).  The theory of abrupt, catastrophic changes to the environment is not conducive to the gradual change of evolution, but when one realized that the world was slowly changed by gradual processes, one might also realize that species might also slowly change to best fit their environment.  This realization is oft implicated as the seed that sprouted the principle of natural selection in Darwin’s mind.  The idea of uniformitarianism does not exclude catasrophism, and indeed aspects of our world were shaped by catastrophic events such as earthquakes and volcanos.  While species gradually evolve to fit their slowly changing environment, acute and catastrophic events introduce a strong selection pressure to survive (and then thrive) in such altered environments.  Catastrophic events can reverse the fortunes of species, creating environments where the former top-species can no longer survive or providing an environment where a previously marginalized group can now thrive.  As the poet Tennyson put it ‘Nature, red in tooth and claw’.

And where does this fit in the concept of ‘paleo’… For 200,000 years, humans evolved to thrive as hunter-gatherers.  This is the niche they evolved to fill.  One might suggest (and indeed I do), that the recent changes in the human environment (and yes, at 10,000 years, I consider agriculture to be a recent change, but I consider the developments of the last century even more pressing) should be considered a ‘catastrophic’ change in an otherwise fairly ‘uniform’ history.  Surely there are some among us that have won the genetic lottery to thrive in this modern world, but most of us did not.  This is evidenced by the growing amount of chronic disease in our communities.  Most of us are not capable of thriving as sedentary, indoor-dwelling, calorically over-nourished and nutritionally malnourished insomniacs.

Humans did not evolve to thrive in a limited niche, eating a specific diet, living and moving in one particular way (if you haven’t watched the BBC series “Human Planet”, I highly recommend it).  We are a species capable of surviving, and indeed thriving, in a multitude of environments and situations.  It seems, however, that the modern world has pushed our capabilities to a breaking point.  Not everything about our modern world is problematic- indeed, humans are better off because of many medical, scientific, technological, and cultural developments   Let us not, however, doom ourselves to lives of chronic disease and malcontent because we are all too eager to step outside the limits of our biology.

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