AS THE SUN set over Lake Eyasi in Tanzania, nearly thirty minutes had passed since I had inserted a turkey baster into my bum and injected the feces of a Hadza man - a member of one of the last remaining hunter-gatherers tribes in the world - into the nether regions of my distal colon. I struggled to keep my legs in the air with my toes pointing towards what I thought was the faint outline of the Southern Cross rising in the evening sky. With my hands under my hips - and butt perched against a large rock for support - I peddled an imaginary upside down bicycle in the air to pass the time as I struggled to make sure my new gut ecosystem stayed put inside me.

With my butt cheeks flexed and my, you know what puckered, I wondered if I had just made a terrible mistake. Could I really displace my western gut microbial ecosystem with that of a man, who, days before had dined on animals as diverse as zebra and monkey, possessed one of the most diverse gut microbiomes of any person in the world? Would my immune system soon freak out at the presence of what should be some familiar Old (microbial) Friends now setting up shop throughout the slimy vastness of my gastrointestinal tract? Or had I just unwittingly infected myself with some lethal bacteria or virus? The pros and cons - mostly cons - of my turkey basting activities raced through my anxious mind as I peddled my way into the evening.

My colleagues and I have been working and living amongst the Hadza hunter-gatherers of Tanzania for over a year now. Over the course of several field sessions, we've collected nearly 2,000 human and environmental samples in an attempt to characterize the microbes on and within the Hadza and the microbes in their environment. The human samples have mostly included stool (feces), but also swabs of hands, foreheads, bottoms of feet, tongues (some spit), breast milk from mothers, and so on. Environmental sampling has included swabs of the plants and other foods they consume - like berries, roots, honey, etc. - and a dizzying number of animals ranging from Greater Kudu, Impala, Dik Dik, Zebra, various monkeys and birds, and so on. For the animals, we collect feces and when possible swabs of the stomach contents of larger animals - all of which end up covering the Hadza sooner or later during butchering (see little blurb in Nature titled Please Pass the Microbes). We also swab their homes - inside and out - along with the various water sources. In short, we swab everything including the researchers while in the field. ...[Continue reading on Humanfoodproject]