When archeologists dig for clues about past civilizations, they typically hope to find bones, tools, pottery fragments, buildings, and the like in order to piece together how those ancient people may have lived and rely on pattern recognition to find out where that group of people originated. However, collaborating with microbiologists has allowed archeologists to get incredibly specific information on ancient people from another source: their fossilized poop. Jessica Rivera-Perez from the University of Puerto Rico - Rio Piedras presented research at the American Society for Microbiology that explains how studying 1,500-year-old stool samples allowed her team to make distinctions between ancient groups living in the Caribbean.

“Although fossilized feces (coprolites) have frequently been studied, they had never been used as tools to determine ethnicity and distinguish between two extinct cultures. By examining the DNA preserved in coprolites from two ancient indigenous cultures, our group was able to determine the bacterial and fungal populations present in each culture as well as their possible diets,” Rivera-Perez explained. 

Human activity in the Caribbean goes back about 6500 years to the Casirimoid people in Cuba. As other humans reached the islands from all different directions and began to expand and settle, many distinct cultures emerged. However, it has not always been easy for archeologists to tease apart where certain groups originated. For instance, decorated pottery and tools that originated 1600-1800 years ago were discovered at a site in Vieques, Puerto Rico. Though the artifacts were in the same location, they had two very different stylings, leading archeologists to speculate that two distinct groups with very different origins had occupied the area. 

“One culture excelled in the art of pottery; in fact, their signature use of red and white paint helped identify them as descendants from the Saladoids, originating in Saladero, Venezuela,” she went on. “In contrast, the second culture had exquisite art for crafting semiprecious stones into ornaments, some of which represented the Andean condor. This helped archaeologists identify the Bolivian Andes as possible origins of this Huecoid culture.”

While it seemed like a reasonable assumption given the evidence, something more concrete was needed. They got the answers they were seeking after analyzing coprolites. They managed to extract DNA from the samples and they discovered a large amount of differences. Some samples also contained corn DNA and fungus, which suggest that those people consumed an alcoholic beverage derived from maize. This also gives weight to the Huecoid coming from the Bolivian Andes, as fermented corn alcohol was quite common in that region.

“The study of the paleomicrobiome of coprolites supports the hypothesis of multiple ancestries and can provide important evidence regarding migration by ancestral cultures and populations of the Caribbean,” Rivera-Perez said.

Even without DNA or protein analysis, coprolites can teach archeologists a lot about a culture. For instance, the amount of undigested plant material helps to indicate how much or even what types of plants were consumed as a regular dietary staple. Additionally, the presence of parasites can indicate what health issues the civilization faced and are helpful in tracking human and disease migration.