A few days ago I accompanied two Hadza hunters to a series of seeps or springs where they had set up hunting blinds of tall grass to ambush thirsty animals. It’s late dry season in Tanzania and dwindling water sources force otherwise dispersed animals to aggregate, and if you’re a hunter-gatherer, this is a good thing. The week before a hunter killed a zebra from one of these blinds with a poison tipped arrow (a windfall of >400-500 pounds of protein and fat that would be consumed in <72 hours!). On our way back to camp, we came across another Hadza that had moments before killed an adult Impala. After helping hoist the deceased into a low hanging tree – to hang by its head for field dressing – I then witnessed something that up until that point I had not fully appreciated the significance of in the co-evolution of humans and our microbes and its potentially profound implications for our health in the so-called modern world.
I had come to Tanzania as part of a collaboration of US, Canadian, and Tanzanian researchers to try and understand what the gut microbiome might look like in a group that still hunts and forage’s 95-100% of its food and more interestingly, how pronounced seasonal changes in resources – between wet and dry seasons – might impact compositional and functional changes in the microbiota. One pressing question in microbiome research – at least what the public and many public health officials wants to know (not to mention food manufacturers and Big Pharma) – is there an optimal composition of gut microbes we should strive for, and at what age, and what diet and lifestyle choices will get us to this microbial fountain of health. Which is, of course, a complex question.
The Hadza may provide some interesting insight into this question as they live in a part of Africa that presumably gave rise to our genus (Homo) and our more distant tree-hugging ancestors. The Hadza still hunt and forage many of the animals and plants that our ancestors relied upon, are covered in the same soil, drink the same water, and follow more or less a seasonal hunter-gatherer lifestyle that dominated the last two million plus years of human evolution. While its important to understand how humans lived once they left Africa and settled other parts of the planet in the last ~60,000 years, the huge spans of time our kind spent in Africa evolving towards the lion’s share of our current physiology (and current adaptive immunity), is potentially more interesting when it comes to understanding the human-microbe relationship – both good and bad.
This thought-provoking and jaw-dropping post by researcher Jeff Leach leads us further toward the link between humans and the messy, germ-ridden natural world that surrounds us. We've tried so hard to shut it all out. To our peril?