The catalogue of microbes living in the guts of a group of human hunter-gatherers, the Hadza of Tanzania, is described in Nature Communications this week. The research identifies unique features in the Hadza’s microbial composition that may be linked to their foraging lifestyle, including an unexpected lack of bifidobacteria, which are commonly considered as ‘good bacteria’ that benefit our health.
Amanda Henry, Alyssa Crittenden and colleagues analysed the bacteria and certain microbial metabolites (short-chain fatty acids, SCFAs) from the faeces of Hadza and Western individuals. They found that the two human groups differed in microbial and SCFA composition, and that Hadza gut bacteria were more diverse. Strikingly, the Hadza lacked bifidobacteria, microbes that are found in the intestine of all other humans and in livestock animals. Another unique feature of the Hadza samples was that microbial composition differed between men and women, possibly due to sexual division of labour.
The Neolithic transition from hunting-gathering to agricultural societies involved dramatic changes in diet and lifestyle, to which both humans and their microbial partners had to adapt. The present work represents an important step in our understanding of such synchronised adaptations, and highlights the fact that the concept of ‘normal’ or ‘healthy’ microbial flora is context-dependent.