About 50,000 years ago, a group of Neanderthals made a house and a bath–of what is now a rocky escarpment in the south of Valencia, Spain. In recent years, some of these paleo-poop, the oldest known of a human species, have been excavated and analyzed. Now, researchers have captured the ecosystems that were in the bowels of these early hominins, from a fecal deposit to the remains of a local fire pit.
An interdisciplinary team of archaeologists, microbiologists and anthropologists extracted more than 200 bacterial microorganisms from the ancient poop. Researchers found a striking consistency between Neanderthal gut microbial residents and the type of microbes that populate the bowels of modern humans. This consistency shows that many tiny inhabitants of our interior are long-time residents, who have lived in us for hundreds of thousands of years, and who have co-evolved with the hominins they inhabit. The investigation was published in the journal Nature Communications Biology.
According to Marco Candela, a microbiologist at the University of Bologna and co-author of the work, the team wanted to “see which microbiomes coevolve with the Man lineage in evolutionary time. ”To do so, they looked for microbes that contemporary humans could share with Neanderthals.
Having an early reconstruction of the human gut is helpful in contextualizing the appearance of our current microbiomes; researchers want to know which bacteria we have left and which have completely disappeared from our internal ecosystems. Microorganisms with strong permanence in the entrails of mammals were called “old friends” in the mid-2000s, and its co-evolution with us has been related to the way humans have lived for hundreds of thousands of years.
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The oldest data on the intestinal microbiome for humans is about 8,000 years old, not even preceding the last ice age, which ended about 11,000 years ago. This has left researchers behind when it comes to understanding the insides of our ancestors. Neanderthal poop dates back 40,000 years, shortly before Neanderthals, as we know them, disappeared from the evolutionary record.
“The point is that we identified some microorganisms that are shared between modern humans and Neanderthals,” Candela said. “This means that these microorganisms populate the intestine of the human lineage before the segregation of Neanderthals and sapiens lineages “.
An important finding in Neanderthal poop was the inclusion of short-chain fatty acid-producing bacteria, many of which allow humans to gain additional energy from dietary fiber, and one researcher suggests that it may have provided benefits for the diet. health to old mothers and their children. But just as good microbes hitchhiked through time in our bowels, so did nurses: researchers also found bacterial pathogens in the feces that surround them, causing oral and dental disease in modern humans.
According to Candela, the microbiomes of populations that live in a traditional and rural way, such as the Hazda, a group of hunter-gatherers in northern Tanzania, tend to have more similar guts. On the other hand, there are humans who inhabit urban environments, which isolate our bowels and make our bacterial residents less similar from person to person. The paper describes a global loss of bacterial diversity in the modern human gut and a situation in which each of our viscera does not talk to each other as they did in our evolutionary past. “Each of us is like an island,” Candela said.
Often the human evolutionary path is framed heroically: of many early humans, ours was the one that was successful. But, as the Neanderthal microbiome demonstrates, we were hardly alone on this journey. Many microorganisms had the same path.
“Based on these results, we can anticipate that the depth of symbiotic time between humans and some co-resident microbes will be at least a million years,” co-author Stephanie Schnorr wrote in Nature block on research. “This implies a fixed physiological relationship that relates to normal development and health in the longevity of both humans and Neanderthals as an ancient legacy.”
Hopefully, more feces will be studied in the future, so we can unpack even more the guts that have made us who we are. For now, we can be thankful that the findings aren’t shit.