Researchers Just Looked at Neanderthal Poop to Understand Their Guts Photo: University of Bologna Around 50,000 years ago, a bunch of Neanderthals made a home—and a bathroom —out of what is now a rocky escarpment south of Valencia, Spain. Over the last few years, some of those paleo-poops, the oldest known to come from a human species, have been excavated and analyzed. Now, researchers have caught a glimpse of the ecosystems that existed in the guts of those early hominins, from a fecal deposit in the remnants of a fire pit on the site. Advertisement Over 200 bacterial microorganisms were extracted from the ancient poop by an interdisciplinary team of archaeologists, microbiologists, and anthropologists. The researchers found a striking amount of consistency between the microbial residents of the Neanderthal gut and the sort of microbes that populate the guts of modern humans. That consistency shows many minuscule denizens of our insides are actually longstanding residents, living in us for hundreds of thousands of years, and have coevolved with the hominins they inhabit.