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.
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. 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.
“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. ’10. “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.”
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. 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 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.
“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. “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?”