Gut dysfunction drives the development of autism. In the early 2000s, very few health practitioners or scientists believed that gut bacteria play a role in the pathogenesis of autism. The few who did and who were vocal about their beliefs were discredited by the medical establishment and frequently labeled as quacks. Fast forward ~15 years and a lot has changed. Not only is it today widely recognized among medical scientists that autism is associated with an abnormal gut microbiota composition, but it’s becoming increasingly appreciated that the gut figures centrally in the development of autism.
We can learn a lot about what it takes to maintain a healthy, supple cardiovascular system from traditional, non-westernized people! A 2017 study found that the Tsimane, a group of indigenous forager-horticulturalists of the Bolivian Amazon, are at extremely low risk of developing heart disease. According to the researchers, they have the lowest reported levels of coronary artery disease of any population recorded to date. The results of this study are aligned with those of other studies that have looked into the cardiovascular health of traditional, non-westernized people, and validate the core tenets of the evolutionary health model.
The key to longevity may lie in the gut. In an interesting study that was published in the scientific journal eLife last year (2017), bacteria were transferred from young fish to middle-aged fish, something that resulted in increased gut microbiota diversity, life span extension, and delayed behavioral decline in the older fish. This study, in combination with other research, shows that gut bacteria contribute to regulating the life span of their host.
The Paleolithic diet is an extremely effective weapon against liver fat. A study that was published earlier this summer found that liver fat decreased by 74% (!) in a group of individuals with type-2 diabetes who ate a Paleolithic-type diet for 12 weeks. This is noteworthy, as fatty liver, AKA hepatic steatosis, is a very common condition nowadays, and can partly be explained by the fact that Paleolithic-type diets are low in sugars and refined fat, while high in fiber and lean protein.
Antibiotics are depressogenic. The use of broad-spectrum antibiotics disrupts the gut microbiota, which sets the stage for gastrointestinal dysfunction, increased intestinal permeability, and chronic inflammation. This, in turn, can lead to feelings of sadness and despair. This emotional response to microbiota disruption and inflammation serves an adaptive purpose, but is unfortunately left unchecked in our evolutionarily abnormal, modern environment.
The Agricultural Revolution caused marked changes in the human oral microbiome. These changes, which included a proliferation of bacteria implicated in the development of periodontal disease, were largely driven by the infusion of large quantities of carbohydrate-rich cereal grains into the human diet. Natural selection still hasn’t gotten around to reconfiguring the human biology so that it matches well with the oral microbiome that is produced by the starchy diet that over the past 10.000 years have replaced the protein-rich, low-carbohydrate hunter-gatherer diet that nourished our Paleolithic ancestors, as evidenced by the fact that the modern man, just like the Neolithic man, runs the risk of developing a variety of oral health problems if he eats a grain-heavy diet.
Both Hadza men and women rank honey as their favorite food. They have developed a remarkable, mutually beneficial relationship with wild birds (“honeyguides”) that help guide them towards honeycomb, which makes up a substantial part of their diet during the wet season, contributing not only plenty of sugar, but also protein and fat in the form of bee larvae. Unfortunately, these types of beautiful, Darwinian relations are severed whenever and wherever technology and industry prevail at the expense of nature.
The Greenlandic Inuit possess unique genetic variants involved in lipid metabolism. This helps explain how they are able to stay healthy while eating an unorthodox diet, very rich in marine fats, while low in plant foods. It’s safe to assume that the relevant alleles have increased in frequency as a result of natural selection.
The fatty acid composition of the typical western diet differs markedly from that of the typical hunter-gatherer diet. Most importantly, the former contains more saturated fat, trans-fat and long-chain omega-6 fatty acids, while less omega-3 fatty acids. This helps explain why most westerners have markedly higher levels of cholesterol and triglycerides circulating in their bloodstream than hunter-gatherers and why many diseases, in particular diseases of the cardiovascular system such as coronary heart disease, are virtually absent among forager populations, while they are common in westernized societies.
Your tongue reveals a lot about your health. If your tongue has a nice pink color and looks healthy, then chances are your oral health, as well as your general gut health, is fairly good. If it’s coated in white material or otherwise looks “off”, on the other hand, then your gastrointestinal microbiota is probably in a somewhat sorry state and you probably have bad breath. The latter situation is today common, in large part because various modern lifestyle habits (e.g., regular consumption of processed, sugary foods) have altered the relationship between man and microbes and given organisms such as Candida albicans an opportunity to proliferate.
The human microbiota – the trillions of microorganisms that colonize the human body – weighs roughly the same as the adult human brain (ca. 1.5 kg). The human colon, in particular, is extremely rich in bacteria. It harbors one of the densest microbial ecosystems on Earth. In total, as much as 100 trillion microbes live in the human gut.
The Darwinian nutrition concept has been validated by modern, experimental research. A new study out of Umeå University in Sweden is the latest addition to the growing list of studies that have found Paleolithic-type diets to be very healthful. The public health professionals who’ve long argued that it’s healthy to eat a lot of grains and drink milk are probably surprised by the results of these studies. Darwinian nutritionists, however, are not. To them, the results merely verify that Darwin was right.
Cow’s milk was designed to promote the growth of calves, not the development or maintenance of the human skeletal system. Several large epidemiological studies showing that dairy consumption correlates positively with hip fracture incidence, such as this one, questions the validity of the general belief that the consumption of calcium-rich dairy foods helps prevent osteoporosis and hip fractures. These studies only reveal correlations, they don’t prove causation; however, they clearly indicate that the relationship between milk intake and bone health is not as straight-forward as many people think it is. If it were true that milk is good for the bones, one would expect the correlation between dairy consumption and bone fracture incidence to be negative, not positive.
Immune status is an important determinant of sleep needs! People who are chronically inflamed typically require more sleep than people who are not inflamed, in large part because their bodies “need” peace and quit as they are trying to restore immune homeostasis. This helps explain why many westerners, in particular those who suffer from inflammation-related disorders such as ME/CFS and IBS, are often tired and sleepy, whereas hunter-gatherers, who typically aren’t chronically inflamed, appear energetic and don’t sleep that much.
The human brain needs exercise to function at its best! One of the primary reasons why it was an advantage for our ancient ancestors to have a large, complex, and vigilant brain is that their ability to track down game animals, locate wild, eatable plant foods, and otherwise navigate their local environment was partly determined by their cognitive prowess. This fact, that there has historically been a close relationship between physical activity and brain function in human evolution, helps explain why modern scientific research has shown that the human brain requires exercise-induced stimuli to perform at its best. By being physically active on a regular basis, you will not only give your memory and cognitive function a boost, but you may actually be making some parts of your brain bigger.
Both men and women are intimately linked with the microbes that colonize their bodies. It could be argued though that the microbiome is in some respects even more important in the context of female reproduction and health than it is in the context of male reproduction and health. A woman’s fertility and vaginal health, including her risk of developing vaginal yeast infections, is greatly affected by the composition of her microbiota. Not only that, but women pass on microbes to their offspring in utero and during birth, breastfeeding, and other forms of physical contact and thereby greatly contribute to shaping the microbiotas and health of their offspring and the co-evolution of man and microbes.
Inflammation drives the development of the diseases of civilization. Inflammation has been implicated in the pathogenesis of almost all of the diseases of civilization, including heart disease, type-2 diabetes, acne vulgaris, and colon cancer. Fast food, cigarette smoke, pollution, artificial lighting, physical inactivity, pharmaceutical drugs, and many other characteristic elements of modern, urban environments and lifestyles contribute to fueling the fire that’s burning inside the modern man. These things were not a part of our primal ancestors’ milieu; hence, the human body has little evolutionary experience in dealing with them. This helps explain why they have been shown to cause inflammation and disease.
The human superorganism is less than it’s ever been. Examinations of ancient coprolites and dental remains have revealed that ancient humans harbored a much greater diversity of both micro and macro-organisms than modern, industrialized people. The same can be said for contemporary hunter-gatherers and non-westernized traditional people, in particular uncontacted Yanomami Amerindians, who were shown in a 2015 study to harbor the greatest diversity of bacteria and genetic functions ever reported in a human group. We humans have co-evolved with various worms and microorganisms. We’ve come to depend on our tiny partners in order to keep our bodies running smoothly. Hence, perhaps needless to say, the loss of biodiversity from the human superorganism has profound implications for our health and well-being.
Pic: Yanomami girl. Source.
Charles Robert Darwin’s wife Emma was a very religious woman. Charles, on the other hand, became increasingly more skeptical of Christianity and religion as he became older and promoted, via his scientific writings, ideas about the origins of man and the natural world that clashed with those of the Church. Emma never fully embraced the evolutionary ideas of her husband. She was afraid that she and Charles would be separated by their conflicting beliefs and that Charles would be punished for his lack of faith. This was likely one of the reasons why Charles hesitated to publish some of his most controversial ideas. He cared greatly for his wife, valued her opinions, and didn’t want to cause her distress.
In industrialized nations such as the U.S. and Sweden, the skin condition acne vulgaris is so common – it afflicts almost all teenagers, as well as many adults – that it’s often considered to be an unavoidable part of human life. Among non-westernized, traditional people such as the Kitavans and the Aché hunter-gatherers, however, acne is a very rare disorder. This clearly suggests that acne vulgaris is a disease of civilization that develops as a result of gene-environment conflicts.
Pic: Kitava girl. Taken by Staffan Lindeberg