the poop gap

westhunt |  There’s a new article out in Science tracing the splits in gut flora. It looks as if the gut bacteria in chimpanzees split with those in humans 5.3 million years: doesn’t quite match our genetic estimates based on Human/chimp autosomal DNA differences, but it’s in the ball park. They estimate the human-gorilla split at 15.6 million year ago, but that can’t be right: we know that gorillas split off just a bit before the human-chimp split. Perhaps gorilla diet changed drastically, and maybe they picked up new bacteria from some other species.

Different populations of modern humans apparently have pretty different microbiomes. The gut bacteria from people in Malawi appear to have diverged 1.7 million years ago from those in Europeans (people from Connecticut). That is surely too old to be a consequence of modern humans’ trek out of Africa: it looks as if AMH, after leaving Africa, picked up gut flora from archaic sapiens like Neanderthals and Denisovans and dwarves.

Microbiomes are trendy. We know that fecal transplants can cure C difficile (pseudomembranous colitis) lickety-split: they might help with Crohn’s disease and ulcerative colitis. Some researchers think the microbiome has something to do with the initiation of multiple sclerosis. Others suspect that it may play a role regulating how people think and feel – in particular, mood disorders. Autism has been mentioned. 

So.. Poop matters: it certainly can affect health, and it may influence brain function. People from sub-Saharan have divergent poop, or you could say that Eurasians do. Are there differences in brain function between sub-Saharan Africans and Eurasians? Sure: Africans do poorly on IQ tests and in academic subjects. They have significant higher rates of schizophrenia, higher murder rates, etc.

Maybe it’s the poop. It’s worth checking out. Perhaps the fault lies not in our stars, or our genes, but in our stool. 

Already, eager experimenters – paleos on stilts – are trying to dramatically modulate their internal flora.