If you’ve followed this site for some time, you may have noticed that I occasionally put up posts in which I list scientific articles covering topics that have to do with Darwinian medicine. The papers I include in such posts are carefully selected, in the sense that I only include articles that I find particularly interesting and informative and worth sharing. The main reason why I go through the “trouble” of crafting such lists is that they may help draw attention to evolutionary nutrition and medicine and get more people to discover real, high-quality science.
About 3 years ago, as well as 1 1/2 years ago, I put up an article in which I listed 10 great scientific papers. (2015 post, 2017 post). So as to continue the tradition, I’ve now selected 10 new papers, all of which I would strongly recommend that people who are interested in health, medicine, and nutrition read…
1. Homo sapiens as physician and patient: a View from Darwinian Medicine
Abstract: Medicine’s cardinal diagnostic and therapeutic resource is the clinical encounter. Over the last two centuries and particularly over the last five decades the function of the clinical encounter has been eroded to the point of near irrelevance because of the atomized and atomizing influence of technology and microspecialization. Meanwhile, over the past five decades the exceptionalist view of Homo sapiens inherent in the social and religious traditions of the West has similarly undergone radical changes. H. sapiens is now best understood as a microecosystem integrated into a much broader ecosystem: the biosphere. that human microecosystem is composed of constituents derived from the archaeal, bacterial, and eukaryan domains via endosymbiotic, commensalistic and mutualistic interactions. this amalgamation of 100 trillion cells and viral elements is regulated by a composite genome aggregated over the 3.8 billion years of evolutionary history of organic life. No component of H. sapiens or its genome can be identified as irreducibly and exclusively human. H. sapiens’ humanity is an emergent property of the microecosystem. ironically as H. sapiens is viewed by evolutionary science in a highly integrated manner medicine approaches it as a balkanized, deaggregated entity through the eye of 150 different specialties. to effectively address the needs of H sapiens in its role as patient by the same species in its role as physician the disparate views must be harmonized. Here i review some conceptual elements that would assist a physician in addressing the needs of the patient in integrum, as a microecosystem, by the former address the latter as a historical gestalt being. the optimal way to recover the harmony between patient and physician is through a revitalization of the clinical encounter via an ecological and Darwinian epistemology.
My comment: Several years back, I stumbled across a paper about Darwinian medicine written by a medical doctor and professor named Ángel A. Román-Franco. I quickly discovered that he’d published two fairly comprehensive papers on the topic, both of which I found fascinating and original. They were unlike anything I’d ever read before. Dr. Román-Franco has a unique approach to Darwinian science and healing. One of the things I like about him is that he’s meticulous, but at the same time, he’s not afraid to speak his mind. His way of thinking differs somewhat from my own, which I find interesting, as he opens me up to new ideas and perspectives.
I included one of the two papers in the previous installment of this series of posts. This time around, I decided to include the second paper, entitled Homo sapiens as physician and patient: a View from Darwinian Medicine. Chances are you’ll find that this article challenges many of your beliefs about health and medicine and gets you to question the popular notion that medicine, as it operates today, is a superb enterprise (“the pinnacle of human achievement”). The paper is somewhat detailed and technical. It’s not a light read. If you find that it’s too heavy, my suggestion is that you read the abstract, as well as the last paragraph of the article. That way you’ll get the gist of what the author is trying to say.
2. Stone agers in the fast lane: chronic degenerative diseases in evolutionary perspective.
Abstract: From a genetic standpoint, humans living today are Stone Age hunter-gatherers displaced through time to a world that differs from that for which our genetic constitution was selected. Unlike evolutionary maladaptation, our current discordance has little effect on reproductive success; rather it acts as a potent promoter of chronic illnesses: atherosclerosis, essential hypertension, many cancers, diabetes mellitus, and obesity among others. These diseases are the results of interaction between genetically controlled biochemical processes and a myriad of biocultural infiuences-lifestyle factors-that include nutrition, exercise, and exposure to noxious substances. Although our genes have hardly changed, our culture has been transformed almost beyond recognition during the past 10,000 years, especially since the industrial Revolution. There is increasing evidence that the resulting mismatch fosters “diseases of civilization” that together cause 75 percent of ail deaths in Western nations, but that are rare among persons whose lifeways reflect those of our preagricultural ancestors.
My comment: This article, alongside a couple of other seminal papers, some of which were penned by the same authors as this one, gave rise to the evolutionary health movement. They are the seeds from which the movement initially grew. In the paper, Boyd Eaton and colleagues point out that humans are inadequately adapted for modern environmental conditions and argue that we should look to our Stone Age ancestors for clues as to how we should go about preventing and treating degenerative disease.
The paper is quite old (It was published in 1988), but it’s certainly not outdated or no longer relevant. Actually, I would argue that it’s extremely relevant. Not just because the message it delivers is very powerful, in the sense that it could transform the world of health and medicine if it were received and appreciated by a lot of people, but also because I think that many ancestral health aficionados have strayed too far from the original evolutionary health template for their own good and could benefit from returning to the basics.
3. A new science of health: salutology and the evolutionary perspective
The first part of the introduction: Traditional medical science is primarily concerned with pathological processes; with understanding disease, illness and sickness; and the causes and management of dysfunction. The starting point is a healthy organism, and medicine seeks to explicate departures from this state of harmony. Thus disease is usually conceptualized and classified in terms of the causes of pathological process—neoplasia, infection, trauma and so on. Yet, while this has proved a valid and fruitful viewpoint, the pathological perspective misrepresents the human situation in important respects. To the eye of an evolutionary biologist it is health, not disease, which requires explanation.
My comment: This is a paper I came across and read very recently. It’s unlike any other article I’ve ever read. The author approaches the topic at hand in a unique way and presents some interesting theories and ideas that I’ve never seen anywhere else. It got me thinking, which is a good sign, as it typically means that I’ve read something that has either challenged my existing beliefs or instilled new ideas or theories in my mind. I still haven’t wrapped my head around all of the information contained within the paper or fully decided where I stand with respects to some of the assertions the author makes. If this piques your interest, then you should strongly consider reading the full paper.
4. A multidisciplinary reconstruction of Palaeolithic nutrition that holds promise for the prevention and treatment of diseases of civilisation.
Abstract: Evolutionary medicine acknowledges that many chronic degenerative diseases result from conflicts between our rapidly changing environment, our dietary habits included, and our genome, which has remained virtually unchanged since the Palaeolithic era. Reconstruction of the diet before the Agricultural and Industrial Revolutions is therefore indicated, but hampered by the ongoing debate on our ancestors’ ecological niche. Arguments and their counterarguments regarding evolutionary medicine are updated and the evidence for the long-reigning hypothesis of human evolution on the arid savanna is weighed against the hypothesis that man evolved in the proximity of water. Evidence from various disciplines is discussed, including the study of palaeo-environments, comparative anatomy, biogeochemistry, archaeology, anthropology, (patho)physiology and epidemiology. Although our ancestors had much lower life expectancies, the current evidence does neither support the misconception that during the Palaeolithic there were no elderly nor that they had poor health. Rather than rejecting the possibility of ‘healthy ageing’, the default assumption should be that healthy ageing posed an evolutionary advantage for human survival. There is ample evidence that our ancestors lived in a land–water ecosystem and extracted a substantial part of their diets from both terrestrial and aquatic resources. Rather than rejecting this possibility by lack of evidence, the default assumption should be that hominins, living in coastal ecosystems with catchable aquatic resources, consumed these resources. Finally, the composition and merits of so-called ‘Palaeolithic diets’, based on different hominin niche-reconstructions, are evaluated. The benefits of these diets illustrate that it is time to incorporate this knowledge into dietary recommendations.
My comment: This is an appealing paper on Paleolithic nutrition that people who are searching for clues as to what constitutes the optimal human diet could definitely benefit from reading. The paper has a unique spin to it, in the sense that much of its focus is on issues that generally don’t receive that much attention in papers like this one. I’m particularly thinking about the attention the authors devote to the role aquatic food resources played in human evolution. I would go as far as to say that the information that’s contained within this paper could revolutionize the world of nutrition if it was brought out into the open and circulated among nutrition students and nutritionists.
5. Friends with social benefits: host-microbe interactions as a driver of brain evolution and development?
Abstract: The tight association of the human body with trillions of colonizing microbes that we observe today is the result of a long evolutionary history. Only very recently have we started to understand how this symbiosis also affects brain function and behavior. In this hypothesis and theory article, we propose how host-microbe associations potentially influenced mammalian brain evolution and development. In particular, we explore the integration of human brain development with evolution, symbiosis, and RNA biology, which together represent a “social triangle” that drives human social behavior and cognition. We argue that, in order to understand how inter-kingdom communication can affect brain adaptation and plasticity, it is inevitable to consider epigenetic mechanisms as important mediators of genome-microbiome interactions on an individual as well as a transgenerational time scale. Finally, we unite these interpretations with the hologenome theory of evolution. Taken together, we propose a tighter integration of neuroscience fields with host-associated microbiology by taking an evolutionary perspective.
My comment: This is one of the most interesting articles on the human microbiome I’ve ever read, and that’s saying something, seeing as the microbiome has been high on the list of my main research interests for a long time. I think the primary reason why I found the article so enthralling is that it presents several new and revolutionary ideas and theories that I’ve never previously come across. It, together with other similar papers that followed in its wake, bring a whole new dimension to the microbiome field.
Up until the time when I came across this article, I hadn’t really considered the idea that microbes could play a critical role in shaping human social behavior. I was convinced that they were involved in regulating our appetite, mood, and eating behavior, among other things; however, I hadn’t given much thought to the concepts outlined in the paper. They really resonated with me though, and I immediately placed them in a part of my brain that holds various fascinating theories and concepts that I’d like to explore further.
6. Cytokines sing the blues: inflammation and the pathogenesis of depression
Abstract: Increasing amounts of data suggest that inflammatory responses have an important role in the pathophysiology of depression. Depressed patients have been found to have higher levels of proinflammatory cytokines, acute phase proteins, chemokines and cellular adhesion molecules. In addition, therapeutic administration of the cytokine interferon-α leads to depression in up to 50% of patients. Moreover, proinflammatory cytokines have been found to interact with many of the pathophysiological domains that characterize depression, including neurotransmitter metabolism, neuroendocrine function, synaptic plasticity and behavior. Stress, which can precipitate depression, can also promote inflammatory responses through effects on sympathetic and parasympathetic nervous system pathways. Finally, depression might be a behavioral byproduct of early adaptive advantages conferred by genes that promote inflammation. These findings suggest that targeting proinflammatory cytokines and their signaling pathways might represent a novel strategy to treat depression.
My comment: In my recent article entitled The Darwinian Causes of Mental Illness I made the case that inflammation is a major, common cause of depression. Part of the reason why I’m convinced that this is the case is that it makes sense from an evolutionary point of view, and because a solid body of scientific evidence indicates that inflammation plays a central role in the pathogenesis of depressive disorders.
The authors of this paper have helped spearhead the research in this area and are very knowledgeable about the inflammatory underpinnings of depression. I think they miss the mark somewhat with respects to the practical solutions they present and discuss in some of their papers; however, there’s no doubt that they know a lot about the etiology of depression. For this reason, I deliberately chose to highlight a paper that mostly revolves around immune-related causes of depression, as opposed to one that includes a comprehensive section covering potential immune-related solutions.
7. The genome, microbiome and evolutionary medicine
Introduction: The revolution in genomics is transforming medicine. Among its important contributions is a demonstration — through a greater understanding of the human genome and the microbiome — that evolutionary biology underpins the principles and practice of medicine. Evolutionary medicine provides the unifying framework by which clinical and public health physicians can incorporate genomics into medicine. It reconsiders the questions, “what is a patient?” and “what is a disease?” Some areas of medicine have already incorporated genomics and evolutionary medicine into clinical practice (e.g., the disciplines of genetics, infectious diseases and cancer care). Other areas of medicine are likely to follow as new research emerges, and the practice of medicine will be increasingly based on an evolutionary understanding of the human genome and microbiome.
My comment: This is a forceful article that was published earlier this year. The reason I say it’s forceful is that the author – Robert C. Brunham – clearly and loudly asserts that evolutionary science is, or at least should be, the foundation of medicine. Not all of the statements he makes completely align with my own beliefs; however, like the author, I strongly believe that Darwinian forces could bring about a medical revolution and that we would be wise to consider evolutionary lessons as we set out to understand, prevent, and cure disease.
8. Low-grade chronic inflammation perpetuated by modern diet as a promoter of obesity and osteoporosis
Abstract: Some of the universal characteristics of pre-agricultural hominin diets are strikingly different from the modern human diet. Hominin dietary choices were limited to wild plant and wild animal foods, while the modern diet includes more than 70 % of energy consumed from refined sugars, refined vegetable oils, and highly processed cereals and dairy products. The modern diet, with higher intake of fat has also resulted in a higher ratio of omega-6 (n-6) to omega-3 (n-3) polyunsaturated fatty acids (PUFA), contributing to low-grade chronic inflammation (LGCI) and thus promoting the development of many chronic diseases, including obesity and osteoporosis. In this review, we describe the changes in modern diet, focusing on the kind and amount of consumed fat; explain the shortcomings of the modern diet with regard to inflammatory processes; and delineate the reciprocity between adiposity and inflammatory processes, with inflammation being a common link between obesity and osteoporosis. We present the evidence that overconsumption of n-6 PUFA coupled with under-consumption of n-3 PUFA results in LGCI and, along with the increased presence of reactive oxygen species, leads to a shift in mesenchymal stem cells (precursors for both osteoblasts and adipocytes) lineage commitment toward increased adipogenesis and suppressed osteoblastogenesis. In turn, high n-6 to n-3 PUFA ratios in the modern diet, coupled with increased synthesis of pro-inflammatory cytokines due to adiposity, propagate obesity and osteoporosis by increasing or maintaining LGCI.
My comment: If you’re a regular reader of this site, then you undoubtedly know that I think diet-induced inflammation is at the root of many of the diseases and health problems that run rampant in westernized human societies. It’s not the only cause of modern illness, but it’s certainly an important one. This idea is supported by a number of scientific findings, some of which are mentioned and discussed in this paper.
One of the interesting things about the paper is that it’s written by a group of researchers who’ve stayed largely out of the “Darwinian limelight”, in the sense that they haven’t yet made a name for themselves within the evolutionary health community. That doesn’t have to be a bad thing though, as immigrants sometimes bring new and fresh ideas with them, thereby augmenting the area they enter.
9. A Darwinian View of the Hygiene or “Old Friends” Hypothesis
The first part of the introduction: The notion that urban life is associated with increases in chronic inflammatory disorders traces back to the 19th century, when physicians in Europe noticed that allergies were rare among farmers. In sharp contrast, hay fever was regarded as the hallmark of prosperous, educated city sophisticates. Several rigorous epidemiologic studies of more recent vintage lend support to the idea that growing up in a farming environment protects children against developing hay fever or other allergies. Further, in 1989 epidemiologist David Strachan of St. George’s University in London, United Kingdom, observed allergies as being less common in children with older siblings, especially boys, suggesting to him that microbial encounters might protect against allergic disorders. Strachan’s and other studies led to the view that microorganisms and macro-organisms from mud, animals, and feces with which mammals coevolved play a critical role in immunoregulation and in inhibiting inappropriate immune responses to self, gut contents, and allergens.
My comment: This is a concise and informative article written by the admirable Dr. Graham Rook. In the article, he explains why it’s important to consider Darwinian theories when one examines the nature and implications of the relationship that humans have with smaller life forms such as bacteria and helminths; a relationship that Rook has written several intriguing papers about. This particular article is great for people who don’t want to spend hours working their way through detailed explanations, but rather just want to get the gist of what the “Old Friends” idea is about, as it’s fairly short and non-technical.
10. Obesity: evolution of a symptom of affluence.
Abstract: This paper delineates the evolutionary background of the unprecedented epidemic of obesity that has evolved over the last century. Some two million years ago, a change of climate in the habitat of our primate ancestors triggered dietary adaptations which allowed our brain to grow. A shift from principally carbohydrate-based to fish- and meat-based eating habits provided sufficient fuel and building blocks to facilitate encephalisation. Insulin resistance may have evolved simultaneously as a means to avert the danger of hypoglycaemia to the brain (in view of the reduction of carbohydrate intake). Ensuing cognitive capacities enabled the control of fire and the manufacturing of tools, which increased energy yield from food even further and eased the defence against predators. The latter development relieved the selective pressure to maintain an upper level of bodyweight (driven by predation of overweight ndividuals). Since then, random mutations allowing bodyweight to increase spread in the human gene pool by genetic drift. Also, (seasonal) food insecurity in hunter-gatherer societies spurred the evolution of thrifty genes to maximise nutrient intake and energy storage when food was available. The agricultural and industrial revolutions rapidly changed our habitat: virtually unlimited stocks of (refined) foodstuffs and mechanical substitutes of physical efforts push up energy balance, particularly in those of us who are still adapted to former environmental conditions: i.e. who carry thrifty genes and lack (genetic) protection against weight gain. Intrauterine epigenetic mechanisms potentially reinforce the impact of these genes on the propensity to grow obese.
My comment: This is one of the best articles about obesity that I’ve ever read. If you’re keen to locate and understand the true causes of the obesity epidemic, then you need to read this article, particularly if you haven’t yet explored adiposity from an evolutionary point of view. I think the author should have devoted more attention to certain topics, in particular the role that microbes play in regulating our appetite and body fat levels; however, all in all, I’d say the article is a very good piece of writing.
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