Tanzania’s Hadza hunter-gatherers have guts teeming with bacteria much more diverse than what’s found in Italians’ intestines. But the foragers don’t have Biﬁdobacterium, which is considered healthy, and do have more Treponema and other microbes that signal disease in Western populations. Hadza men and women even have major differences in their gut microbes.
These differences reinforce the idea that a healthy collection of gut bacteria depends on the environment in which people live and their lifestyle, researchers report April 15 in Nature Communications. The results also show how gut microbes may have helped human ancestors adapt during the Paleolithic period 2.6 million to 10,000 years ago.