JENA, GERMANY—According to a Science Magazine report, an international team of researchers analyzed oral bacteria in dental plaque collected from ancient modern humans, Neanderthals, and other primates, including chimpanzees, gorillas, and howler monkeys. The researchers found that the oral microbiome of modern humans who lived some 10,000 years ago strongly resembled that of Neanderthals who lived as early as 100,000 years ago. Both the modern humans and the Neanderthals carried a bacteria linked to breaking down starches into sugars, and consuming sugars left behind on the teeth. This bacteria was not found in the mouths of chimpanzees. The researchers therefore suggest that the presence of this bacteria indicates ancient modern humans and Neanderthals had adapted to eating a diet heavy in starchy plant foods. The researchers also suggest that modern humans and Neanderthals inherited these sugar-loving microbes from a common ancestor that lived more than 600,000 years ago, at about the same time their brains grew larger. It had been previously thought that this brain growth was fueled by a diet heavy in meat. “For human ancestors to efficiently grow a bigger brain, they needed energy dense foods containing glucose,” said molecular archaeologist Christina Warinner of Harvard University and the Max Planck Institute for the Science of Human History. “Meat is not a good source of glucose,” she concluded. For more on the study of the ancient human microbiome, go to "Worlds Within Us."