Living and working among Tanzania's Hadzabe people — one of the world's last remaining hunter-gatherer groups — I witnessed the extraordinarily intimate relationship they share with microbes in their environment. This potentially provides them with a health-enriching source of gut microbial diversity, lost long ago in the modern lifestyle of the developed world.
Microbial matter as hand cleanser.
Like the Hadzabe, all humans were presumably once connected to a huge microbial metacommunity through the guts, skin and feathers of animals in their territory. As well as sharing water sources tainted with the urine and faeces of animals as diverse as zebras, giraffes and bush pigs, the Hadzabe often consume the uncooked stomachs and colons of killed animals. They also 'clean' their hands in the animals' partially digested and microbe-laden stomach contents (pictured), helping to transfer microbes among community members.
The lower diversity of gut microbes among populations in the developed world (see, for example, T. Yatsunenko et al. Nature 486, 222–227; 2012) may increase our susceptibility to opportunistic pathogens and diseases. We should be exploring the value of the Hadzabe people's rich microbial sources, notwithstanding fundamental issues of sanitation and hygiene.