Less autism among masters of the microbe

March 18, 2019


David Glenn

Zenith News


In previous installments of this long-winded discussion of autism causes, we have touched on genetic mutation as a possible contributing factor. While those aberrations may set the stage, they cannot explain all occurrences of Autism Spectrum Disorder, especially in light of the host of other comorbid ailments.


We looked into the abnormal neurological development seen in brain scans and how malfunctioning microglia might be pruning synapses in a helter-skelter fashion. We examined maternal inflammation during pregnancy as an impetus to this continued inflammatory response, which might explain the variety of autoimmune disorders associated with autism.


We next looked at epigenetic factors that cause genes to express themselves in an unintended manner. The high number of reported cases of autism in the Somali immigrant community further drives home the idea that the inherited genetic mutations theory falls flat on its face in light of zero family history.


Following this line of thought, we examined the lifestyle changes experienced by Western immigrants. Diet seems to be the biggest change and might well have repercussions as it negatively alters the diversity of gastrointestinal microbes.


We then looked at current research into the microbiome’s role in autoimmune and gastrointestinal disorders. This month, we travel to Africa to examine the differences in diet, lifestyle, and microbiome.


The Hadza of Tanzania are important to the study of the microbiome before modern humans first ventured out of Africa. Species, such as humans, either reach a point of homeostasis with their environment and keep on keeping on, or they go extinct.


There must have been a collection of phylum and families of microbiota that humans co-evolved to utilize. Not only do a small number (100-200) of Hadza still live a hardcore hunter-gather lifestyle, but they also have Olduvai Gorge where Lucy the Australopithecus was discovered in their backyard. While other hunter-gathers around the world may have microbiomes as diverse, those populations saw significant changes as they migrated across the globe, rather than an unbroken vertical transmission of enteroflora that humans are semi-hardwired to accommodate.


The Hadza diet consists of insane amounts of fiber (10 times the US Recommended Daily Allowance) in the form of tubers, baobab fruit, vegetable matter, and berries. Hadza children are often mistaken for rickets sufferers due to their distended stomachs. The bloating is not caused by disease, but by fermentation of fiber.


Their diet fluctuates following seasonal trends, as do the dominant families of bacteria in their microbiome. They are always snacking, but are never hungry due to their fiber intake. The Hadza diet also includes a fair amount of red meat and animal fat, but zero dairy.


Compared to Western diets they also consume an inordinate amount of honey—depending on the season, anywhere from one percent to 19 percent of their total caloric intake. Despite this, obesity and Type II diabetes are relatively unknown among the Hadza.


They often mix honey with baobab fruit powder, but the preferred method is to eat the entire honeycomb—wax, bee larvae, and all. A species of bacterium, Melissococcus plutonius, which sometimes runs rampant in the guts of bee larvae, has turned up in Hadza samples. It is still unknown what role it might plays in the Hadza microbiome, but within bees, it competes for sap sugars.


This suggests raw food may come prepackaged with its own helper microbes. This hypothesis is further confirmed by the families of bacteria that dominate the Hadza microbiome and their seasonal fluctuations.  


Slackia, Pseudomonas, Prevotellaceae, Treponema, and Lachnospiraceae are families of bacteria found in soil and in the roots and leaves of plants. Their abundance in nearly all African sampling groups, both rural and urban, is contrasted by their almost complete absence in samples from Europeans and Americans. Many of are pathogenic, causing diseases like pneumonia, syphilis, and botulism.


Within the Hadza, the pathogenic nature of these strains is negated through as-yet unidentified mechanisms, but they break down fiber to maintain a healthy gut wall, mediate inflammation, and enhance the autonomic nervous system. The Hadza microbiome is conspicuously absent of two bacteria that Westerners consider probiotic, Bifidobacterium and Lactobacillus.


The Hadza are in direct daily contact with dirt. Not only soil, but blood, bile, unfiltered water, baby shit, and everything else that we in the West try so hard to sanitize from our lives. The Hadza also do not suffer from the types of autoimmune disorders currently exploding through Western populations.


Is there a difference between Hadza dirt and that found in the slums of Calcutta where diseases are more prevalent? Yes, say several researchers. Many of the world’s industrialized poor are exposed to anthropogenic toxins as well as decay-causing bacteria and fungi. They are also separated from more beneficial organisms by diet and the framework of urbanization.


Pick up a copy of the Zenith next month as this series concludes with an exploration of the role of bees, berries, diet, and dirt in microbiome diversity.

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