Link: 'Ancestral' microbiomes

Ed Yong covers a new preprint quantifying the microbiome diversity of hunter-gatherer people in Cameroon, in comparison to local agricultural people: “Surprises Emerge As More Hunter-Gatherer Microbiomes Come In”. The main finding is that microbiome diversity is determined by parasite load:

Regardless, these results throw up some interesting questions. Is the higher diversity of the hunter-gatherer microbiome down to the wider diets of their owners, or to a wider range of parasites? After all, Morton found that if the Cameroonians had a triple-bill of parasites, including a roundworm and a whipworm along with Entamoeba, their microbiomes were even more diverse. Diversity is generally seen as a good thing. Is it?

A naive prediction from community ecology would be that a harmful element disrupting the microbiome should restrict its diversity, not increase it. But from the view of the microbes, the parasites add nutrients to the gut system by extracting more energy from the host, creating opportunities for microbial niches that may not be there in a healthy gut. Your microbiome is not all about you, after all.

Yong also includes a nice discussion of the misconception of “ancestral” or “more ancient” as applied to microbial diversity:

Hold on, though. The Hadza and the Matses are not ancient people, and their microbes are not “ancient bacteria”, as one headline stated. They are modern people, carrying modern microbes, living in today’s world, and practicing traditional lifestyles. It would be misleading to romanticise them and to automatically assume that their microbiomes are healthier ones.

The entire post is a great warning against the oversimplification of microbiomes, diet, and health.