What the analysis of Neanderthal fecal remains tells us

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Analysis of fecal remains (or coprolites) from Neanderthals has isolated several hundred microorganisms common to modern humans. This work suggests that some of our gut bacteria have lived in our gastrointestinal tract for several hundred thousand years.

About 50,000 years ago, a group of Neanderthals settled under a rocky escarpment south of Valencia, Spain (archaeological site of El Salt). In recent years, researchers have been able to analyze several coprolites (mineralized, fossilized excrements) found on site, giving us unprecedented insight into the gut microbiota of Neanderthals (the microbial composition of their gastrointestinal tract).

This work, the results of which are published in Nature Communications Biology, allowed to isolate over two hundred common bacterial microorganisms in Neanderthals and Homo Sapiens. On this observation, the international team of researchers, led by the University of Bologna, hypothesizes that certain components of the human microbiota lived in our gastrointestinal tract even before the separation of our species from the Neanderthals there is. over 700,000 years.

The oldest data on the gut microbiome for humans so far dates back to around 8,000 years. This study therefore sets this chronology back by around 40,000 years, shortly before the Neanderthals disappeared from the evolutionary archives.

Why is this discovery important?

The gut microbiota is a collection of trillions of microorganisms that inhabit our gastrointestinal tract. It performs essential functions in our body. These include the regulation of our metabolism and our immune system, and protection against pathogenic microorganisms.

However, recent studies have shown that in western urban populations, the consumption of processed foods, drugs or the fact of living in hyper-disinfected environments lead to a critical reduction of biodiversity in the gut microbiota.

The finding is worrying, insofar as some of these components are crucial for our physiology. The steady rise in the rates of chronic inflammatory diseases such as inflammatory bowel disease, type 2 diabetes, and colorectal cancer is in part due to this lack of microbial diversity in our gut.

A Neanderthal family. Credits: Field Museum.

Hence the importance of this new study. Thanks to these DNA analyzes collected at El Salt, the researchers were able to isolate an ancestral “nucleus” of microorganisms, “old friends”, as they are called, shared between Homo sapiens and Neanderthals. In other words, it is a population of bacteria visibly essential to our evolution.

Among them are well-known organisms such as Blautia, Dorea, Roseburia, Ruminococcus and Faecalibacterium which regulate our metabolic and immune balance. The authors have also isolated the bifidobacterium: a microorganism playing a key role in the regulation of our immune defenses, especially in early childhood.

If we already knew that all these bacteria (and there are others) were essential to our health, we now know that they are also ancestral, thus contributing to the success of our evolution. In the current modernization context in which there is a progressive reduction in the diversity of the microbiota, this information could thus guide integrated strategies adapted to diet and lifestyle to protect these microorganisms.

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