Harvard Medical School Over the past several years, scientists have generated intriguing insights suggesting that variations in gut microbiomes-the collections of bacteria and other microbes in our digestive systems-may play harmful roles that precipitate the development of diabetes and other diseases. By ERIC BENDER, Joslin Diabetes Cente Now, researchers at Harvard Medical School and Joslin Diabetes Center have found dramatic differences between gut microbiomes from ancient North American peoples and modern microbiomes, offering further clues about how these microbes may have evolved with changing diets. For the study, the scientists analyzed microbial DNA found in indigenous human paleofeces (desiccated excrement) from unusually dry caves in Utah and northern Mexico.