![]() ![]() The findings also push back on the idea that Neanderthals were top carnivores, given that the “brain requires glucose as a nutrient source and meat alone is not a sufficient source,” Warinner said. “It seems to be a very human-specific evolutionary trait that our Streptococcus acquired the ability to do this,” Warinner said. The genetic machinery the bacteria uses to do this is only active when starch is part of the regular diet.īoth the Neanderthals and the ancient humans that scientists studied had these starch-adapted strains in their dental plaque while most of the primates, who feast almost exclusively on non-starchy plant parts, like fruits, stems, and leaves, had almost no streptococci that could break down starch. These strains, which are members of the genus Streptococcus, have a unique ability to capture starch-digesting enzymes from human saliva, which they then use to feed themselves. The biggest surprise from the study was the presence of particular strains of oral bacteria that are specially adapted to break down starch. It’s similar in theory to how archeologists painstakingly piece together ancient broken pots, but on a much larger scale. Using newly developed tools and methods, they genetically analyzed billions of DNA fragments preserved in the fossilized plaque to reconstruct their genomes. The scientists analyzed the fossilized dental plaque of both modern humans and Neanderthals and compared them to those of humanity’s closest primate relatives, chimpanzees and gorillas, as well as howler monkeys, a more distant relative. ![]() “If we only have people today that we’re analyzing from completely industrialized contexts and that already have high disease burdens, is that healthy and normal? We started to ask: What are the core members of the microbiome? Which species and groups of bacteria have actually co-evolved with us the longest?” “For a long time, people have been trying to understand what a normal healthy microbiome is,” said Warinner, assistant professor of anthropology in the Faculty of Arts and Sciences and the Sally Starling Seaver Assistant Professor at the Harvard Radcliffe Institute. The goal was to better understand how the oral microbiome - a community of microorganisms in the mouth that helps protect against disease and promote health - developed, since little is known about its evolutionary history. Researchers reconstructed the oral microbiomes of Neanderthals, primates, and humans, including what’s believed to be the oldest oral microbiome ever sequenced - a 100,000-year-old Neanderthal. The findings come from a seven-year study published Monday in the Proceedings of the National Academy of Sciences that involved the collaboration of more than 50 international scientists. ![]() “It’s evidence of a new food source that early humans were able to tap into in the form of roots, starchy vegetables, and seeds.” “We think we’re seeing evidence of a really ancient behavior that might have been part of encephalization - or the growth of the human brain,” said Harvard Professor Christina Warinner, Ph.D. ![]() And while these early humans probably didn’t realize it, the benefits of bringing the foods into their diet likely helped pave the way for the expansion of the human brain because of the glucose in starch, which is the brain’s main fuel source. The findings suggest such foods became important in the human diet well before the introduction of farming and even before the evolution of modern humans. By using this novel photographic approach, our study shows that molar eruption in our chimpanzees is not delayed relative to captive animals and both are very similar to data gathered from fossils of early human ancestors.A new study looking at the evolutionary history of the human oral microbiome shows that Neanderthals and ancient humans adapted to eating starch-rich foods as far back as 100,000 years ago, which is much earlier than previously thought. Prior to this study, almost all the research on dental development in chimpanzees came from captive individuals or from a small sample of skeletons collected in the wild and it is unclear how representative these data are of living wild animals. Since chimpanzees are our closest living relative, it is important to make sure that we document their development before we can fully interpret the fossil evidence. Understanding the timing of these developmental milestones in wild chimpanzees is particularly important because evolutionary anthropologists have been debating for years whether early humans followed ape-like or human-like patterns of growth. Azania, one of our female infants, showing that both of her lower first molars (M1s) have erupted before this photo was taken at age 3.1 years. ![]()
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