Scientists find dramatic differences between ancient gut microbiomes and modern microbes Scientists are rapidly gathering evidence that variants of gut microbiomes, the collections of bacteria and other microbes in our digestive systems, may play harmful roles in diabetes and other diseases. Now Joslin Diabetes Center scientists have found dramatic differences between gut microbiomes from ancient North American peoples and modern microbiomes, offering new evidence on how these microbes may evolve with different diets. The scientists analyzed microbial DNA found in indigenous human paleofeces (desiccated excrement) from unusually dry caves in Utah and northern Mexico with extremely high levels of genomic sequencing, says Joslin Assistant Investigator Aleksandar Kostic, PhD, senior author of a