Our bodies are home to millions of microbial cells of thousands of bacterial species, which is known as the microbiome, which is a group of microbes essential to our health.
Within this group, bacteria that live in the oral cavity play an important role in the development of diseases, but it remains unclear how this microbial community evolved.
To analyze the evolutionary history of the oral microbiome of hominids, a scientific team – made up of researchers from 41 centers in 13 countries – analyzed the fossilized dental plaque of humans and Neanderthals from the past 100,000 years and compared it with chimpanzees. Wild gorillas and howling monkeys, a genus of primates from South America.
The work, led by scientists from the Max Planck Institute for the Science of Human History (MPI-SHH), has been published in the Proceedings of the National Academy of Sciences (PNAS).
Paleontologists have studied billions of DNA fragments and have identified bacteria preserved for thousands of years in archaeological tooth accounts, including those of the 100,000-year-old Neanderthals from the Pichtorina Cave (Serbia), the oldest successfully reconstructed oral microbiome to date.
From the start, the study showed that the bacterial DNA of the oral microbiome is preserved “at least twice as long as previously thought,” says James Fellowes Yeats, lead author and doctoral candidate at the Max Planck Institute for the Science of Human History.
In addition, the analysis revealed that dozens of groups of bacteria remained throughout the evolution of the African hominin, a bacterium that was also present in howler monkeys, indicating that these microbial groups played a major role over 40 million years.
The authors also found important differences in the microbial features of humans and chimpanzees, but there are striking similarities between Neanderthals and modern humans, albeit with slight differences, particularly in bacterial strains.
Thus, they discovered that bacterial strains similar to those of Neanderthals disappeared in humans about 14,000 years ago, after an important population regeneration produced in the last Ice Age in Europe.
One of the biggest surprises was the discovery of a subset of Streptococcus bacteria (found in both humans and Neanderthals) that seemed to have been specifically adapted to consuming starch in the early stages of human evolution, suggesting that starchy foods became important in the human diet long before long. The introduction of agriculture, in fact, even before the development of modern man.
Starchy foods like roots, tubers and seeds are rich sources of energy, and previous studies have argued that the switch to starchy foods may have helped our ancestors develop the great brains that characterize our species.
“Reconstructing what was on our most ancient ancestral list is challenging, but our mouth bacteria may hold important clues to understanding the early dietary changes that made us unique humans,” explains Christina Wariner, the study’s lead author. Harvard university.