8  The Gut Microbiome
On the whole, Hadza women generally collect plant foods, and they rely
more heavily on tubers throughout the year. Women have overall higher plant
consumption and therefore more fiber intake than men. This greater dietary
fiber has led to differences in Hadza women’s gut microbiome. The gut micro-
biota of female Hadza better supports digestion and energy extraction from
fibrous plant foods. In this way, gut microbes have adapted to ensure that
women’s foraging is adequate to meet nutrient requirements during pregnancy
and lactation.
The Yanomami: Amazonian Hunter-Gatherers
Another highly significant group in the quest to identify the hunter-gatherer
gut microbiome are the Yanomami of Venezuela. Until the 1960s, the Yano-
mami had lived in isolation within the Amazon jungle for over 11,000 years.
While there are approximately 35,000 Yanomami, one unmapped village was
recently discovered deep in the rainforest. This uncontacted Yanomami group
has had significantly less interaction with the Westernized world than the
Hadza, and their lifestyle remains preserved without much outside influence.
The Yanomami offer particularly interesting insight into the dietary ­
influences of the gut microbiome. The gut bacteria of the uncontacted ­
Yanomami has the highest microbial diversity of any human group yet
observed. Unfortunately, extensive research on diet composition of this group
is lacking, but parallels between the diet of these uncontacted Amazonians
and the Hadza point to higher fiber and plant diversity as the explanation
for increased microbial diversity. The Yanomami were observed to eat wild
bananas, plantain, and other fruit, as well as tubers such as cassava. They hunt
mostly small animals, although animal sources likely do not make up the bulk
of caloric intake. ­ Considering the high biodiversity within the Amazon rain-
forest, it is expected that foraging groups within this environment rely heav-
ily plants. Although further research on this indigenous group would reveal a
more comprehensive understanding of how their diet influences gut microbi-
ota, future studies should be done cautiously, with the protection of this unique
village taking precedence.
High-Fat, Low-Carbohydrate Hunter-Gatherers
Thus far, we have taken an in-depth look at the gut microbiota composition of
both traditional and hunter-gather societies, but these diets have been charac-
terized by high carbohydrate intake. Other traditional diets, such as that of the
Inuit of the Canadian Arctic, are low in carbohydrates and high in animal fat
and protein. While the traditional Inuit diet is based on a hunger-gatherer life-
style, Inuit individuals are now consuming a more Western diet. Many Inuit
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