animal host 7,412 host-associated 7,412 digestive tract 7,410 intestine 7,404 mammalian host 7,224 human host 6,868 industrialized 5,566 adult 3,208 urban 919 elderly 544 rural 536 non-industrialized 462 child 369 infant 188 traditional agriculturalist 142 adolescent 117 hunter-gatherer 50 full term birth 33 rumen 13 agriculture 6 anthropogenic 6 ancient microbiome 4 preterm birth 3 insect host 2