The Fascinating Gut of the Hadza Hunter-Gatherers
WHAT MAKES THE GUT
OF THE HADZA HUNTER-GATHERERS
IN EAST AFRICA SO FASCINATING
The human gut microbiota (GM) is said to be vital for hosting nutrition, metabolism, pathogen resistance and immune function and it varies with diet and lifestyle environment.
The Hadza of Tanzania have been found to have a high level of microbial richness and biodiversity. These hunter gatherers live in rural communities away from industrialization allowing higher biodiversity when compared to western populations. This allows scientists to have a better understanding of GM activity because Hadza rely less on antibiotics and sterile cleaners, and often consume a greater breadth of unrefined seasonally available foods.
Humans have relied on hunting and gathering for 95% of our evolutionary history, so the Hadza provide a snap shot of how our pre-industrial ancestors gut microbiota may have looked like before farming came into the picture.
To study the difference between the ancient and modern gut, researchers analyzed stool samples from 16 Italian urbanites and 27 Hadza foragers, of both genders.
The Hadza who chose to participate in this study came from the Dedauko and Sengele camps, situated in the Rift Valley ecosystem around the shores of Lake Eyasi in northwestern Tanzania. These participants are part of the ~200–300 traditionally living Hadza, who are one of the last remaining hunting and gathering communities in the world.
While the Hadza are a modern population, they live in a key geographic region for studies of human evolution and their way of living is similar to our ancestors back in the day. The Hadza lifestyle therefore is thought to most closely resemble that of Paleolithic humans.
The Hadza diet consists of wild foods that fall into five main categories: meat, honey, baobab, berries and tubers. They practice no cultivation or domestication of plants and animals and receive minimal amounts of agricultural products from external sources.
What difference were discovered between the ancient and modern gut
The Italians’ gut flora was generally what scientist expected in Western diets, with some Mediterranean influences. The Hadza’s poop, however, was like stepping into a lost continent of microbe biodiversity. “The Hadza gut mibrobiome has an entirely unique combination of bacteria from any western population, or rural African population, that’s been sampled,” said co-author Alyssa Crittenden, a nutritional anthropologist from the University of Nevada, Las Vegas.
Many of the Hadza bacteria are species that the researchers had never seen before. And even familiar microbes were present in unusual levels in the Hadza belly. “The Hadza not only lack the ‘healthy bacteria,’ and they don’t suffer from the diseases we suffer from, but they also have high levels of bacteria that are associated with disease,” Crittenden said.
In westerners, Bifidumbacterium is a microbe that many nutrition scientists thought was essential to good gut health, but it is almost completely absent in the foragers. Likewise, high counts of the bacteria Treponema have been linked to maladies like Crohn’s disease and irritable bowel syndrome. Neither of these diseases exist among the Hadza, but their guts contain abundant Treponema.
What was discovered between the Hadza Women and Mens diets
What really surprised the researchers was how different the gut communities were between the sexes. The females had much higher levels of several bacteria known to break down fibrous veggies.
Women selectively forage for tubers and plant foods, and spend a great deal of time in camp with children, family members and close friends. Men are highly mobile foragers and range far from the central camp site to obtain game meat and honey. Although all foods are brought back to camp and shared, men and women consume slightly more of their targeted foods from snacking throughout the day.
For the research team, this was just more evidence of how much the gut biota can vary, even between people who spend their entire lives eating different quantities of roughly the same diet.
Hold on before trying to start a Hadza Diet
That’s not to say you should start stocking up on exotic roots, berries, and wild game hoping to create the perfect balance of beneficial bacteria for your belly. Crittenden and her research partners warn against turning their research into a diet, even if the link between the Hadza’s gut microbiome and their lower rates of gastrointetinal illness prove true. “Even if you try to emulate the diet of the Hadza, you’re not living in the environment,” explained Amanda Henry, a dietary ecologist from the Max Planck Institute in Germany, and a co-author of the study. “There are transfers from the soils, from the animals.” In other words, it’s not just what the Hadza eat that contribute to their remarkable gut flora, it’s where and how they are eating it, too.
Still more research needs to be done
Henry says she’d like to get samples from more people, and across a broader swath of time. “We really need to look at how gut microbiomes vary by season,” she said.