June 2, 2023
The people of the hadza tribes of Tanzania harbor an incredibly diverse microbiome, due their hunter-gatherer based diets. The Hadza, who live in the central Rift Valley are some of the last remaining hunter-gatherers in Africa. Because of this they are of keen interest to researchers interested in the effects modern life has had on microbiome composition.
Though there have been many benefits of modern life - decrease in death from infection and disease - microbiologist are now interested in examining the negative impacts our modern lives have wrought. Specifically the destruction it has caused to the bugs and bacteria living inside our guts.
Before we jump into how diverse the Hadza microbiome is, let's first examine why the western microbiome is so depleted in comparison.
Loss of microbial diversity in humans is happening at a quicker rate than you might imagine. In fact, a study from the University of Minnesota, showed that significant changes and loss in microbial diversity can set in within a generation of people. The study showed that, for immigrants from Thailand, moving to the United States and adopting a western style diet sharply decreased their bodies microbial diversity.
Due to the increasingly widespread loss of microbes, scientists have issued a call to create a bacterial vault. The proposal (very similar to the already existing seed vault) calls for storing as many of the world microbes as possible in an arctic vault, in order to study them and save them in case they one day go extinct.
Scientists are studying the Hadza in order to better understand what our ancestral microbiomes may have looked like and how they evolved to their current states. They are also interested in determining how we may best preserve our microbiomes through diet and other lifestyle choices, without compromising our health or abandoning modern healthcare and life all together.
The team of researchers led by Justin L. Sonnenburg collected 350 stool samples of Hadza over the course of a year and compared their composition 17 other cultural groups from around the world. The other groups included some other hunter-gatherer tribes in Venezuela and Peru and other more westernized communities.
What the research ended up showing was basically this, the further one’s diet is from the western diet, the more diverse their microbiome is. In fact not just diverse, different all together. There are bacteria found in the guts of hunter-gatherers that are simply not present in American guts.
What they concluded was that the western diet - which is low in fibre and high in fat and sugar - pretty quickly kills off whole species of bacteria living in our guts. But the news isn’t all bad.The study also focused on the seasonal changes in the Hadza microbiome and saw significant shifts in their microbiome composition from the wet to dry season.
What this means is that it may be possible for our microbes to be salvaged by eating a better diet. Sonnenburg is convinced that fibre may be the key to this microbiome enriching diet.
The Hadza are a part of a rare category of peoples that sustain themselves through hunting and gathering. Their diet consists of meat, honey, berries, tubers and baobab found or caught in the wild and they do not engage in any farming or cultivation techniques. This lack of cultivation is also noted as a large factor in their microbiomes distinctiveness.
Another cohort studied was an Italian group whose diet is derived mostly from commercial agriculture. And though this group ate a diet abundant in plants, fresh fruits and other whole foods (a Mediterranean diet), their microbiomes presented many differences to the Hadza.
Scientists are hoping that by studying the microbiomes of the Hadza they can get a glimpse into the historical microbiome – which has long been lost in those living in the industrialized world. They are also hoping to be able to find a way to preserve some of these microbes, figure out what they do and then store them for possible future use.
Researches have expressed urgency in studying groups such as the Hadza, who have been largely untouched by modern technology and life, as that is not likely to remain the case. But studying these groups also presents a risk. The risk being that by studying them, scientists may be accelerating that process of microbial loss through the introduction of modern technology and products.