The Human Microbiome

This article from the frontiers of extreme science is very interesting:
(Re)Becoming Human: what happened the day I replaced 99% of the genes in my body with that of a hunter-gatherer

(Warning: fecal transplant description)

If we squint for a moment and consider the Hadza and the seasonality of our ancestral past and its impact on our shape shifting gut microbiota as relevant to populations in the western world – and no reason we shouldn’t, though some may argue otherwise over hair splitting details – then we might need to start rethinking an entire industry of probiotics and the like that suggest we need a certain set of bugs in this drink or that slimy yogurt. And since we are on the subject of probiotics, some significant and dominant players on the market today include characters with names like bifidobacterium and lactobacillus. Interestingly, while the Hadza harbor bifidobacterium and lactobacillus while still breast-feeding, these bugs are essentially absent in Hadza post-weaning (i.e., more or less absent after age 5).

This begs the question: should we really consider these groups of bacteria as essential and necessary to human health despite what a multi-billion dollar industry tells us? Clearly, mountains of research suggest these lactic acid bacteria are good for us, but are there other – more ancestral – groups of bugs that may be more in tune with our seasonal gut post-weaning? More importantly, does the persistence of bifidobacterium and similar bugs in our western gut – mainly due to continued consumption of cow’s milk, ingestion of some probiotic/prebiotic foods, and so on into adult life – nudge out or blunt down other members of our gut ecosystem that would otherwise flourish and provide important ecosystem services? We are currently trying to understand this as we perform various co-occurrence analyses of the Hadza data. Stay tuned.

See also: Gut Bacteria May Affect Brain Function and mind-controlling parasites.