host-associated 1,533 animal host 1,533 intestine 1,532 digestive tract 1,532 mammalian host 1,424 human host 1,305 industrialized 1,082 adult 624 urban 144 elderly 79 rural 68 non-industrialized 58 child 29 infant 17 hunter-gatherer 13 adolescent 12 traditional agriculturalist 11 ancient microbiome 2 agriculture 1 skin 1 anthropogenic 1