4  The Gut Microbiome
environments like savannas. As hominins were learning how to thrive in
new habitats, technology also began to transform the human diet. The use
of fire became one of the first technological advancements that propelled
another major dietary shift for early humans. Again, archeologists noticed
significant physiological changes from this period, although this time as a
result of the dietary transition to cooked food. The introduction of softer
cooked foods led to a reduction in tooth size. Over time, these new diets
caused the gut to compartmentalize, improving nutrient absorption. As
cooking increased digestibility of foods, humans were likely able to eat
plants that might otherwise have been unpalatable. The growing diversity
of plants within the ancient hunter-gatherer diet is particularly relevant for
the microbiome. In modern times, a traditional diet with a greater variety
of minimally processed plant foods is associated with more diverse gut flora
than a Western diet.
Modern-Day Hunter-Gatherers: The Hadza of Tanzania
Archeological research provides only limited insight into the diet and gut
microbial composition of early foraging humans. Fortunately, microbiologists
and anthropologists are collaborating to study the last few surviving indigenous
populations that practice foraging or other traditional dietary patterns. The
hunter-gatherer diet is not universal, and in fact, nutritional patterns among
current-day hunter-gatherer communities around the world are greatly varied
based on the availability of plant and animal resources. The closer a population
is to the equator, the more reliant they are on gathering. This is not surprising,
considering the immense plant biodiversity found in these warmer habitats.
Hunter-gatherer communities living in the coldest regions rely more on hunt-
ing. All foraging groups share one commonality: their mode of subsistence
exerts only little control over their habitat and reproduction of resources. This
is in contrast to food cultivation and farming that involves deliberate manipu-
lation of the environment for subsistence.
One of the world’s last remaining hunter-gatherer groups, the Hadza of
northwest Tanzania, live in the same East African region inhabited by early
hominins. They are an ideal example of an indigenous community whose tra-
ditional lifestyle has remained mostly unchanged despite the advancements
of surrounding populations. While the Hadza are still considered a modern
human population, their dietary resources are similar to those of our hom-
inin ancestors. To investigate what the microbiome of our ancestors may have
looked like, researchers examined the gut bacteria of the Hadza in the context
of their traditional unprocessed diet. As expected, their gut microbiota proved
to be reflective of their diet. The Hadza have great microbial richness and
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