Folks began loving carbohydrates a really very long time in the past

From Cara Murez

HealthDay reporter

WEDNESDAY, May 12, 2021 (HealthDay News) – Not only have humans and their ancient ancestors been eating carbohydrates longer than previously thought, but a new study found that these starchy foods may actually have contributed to the growth of the human brain.

A new study examining the history of the human oral microbiome found that Neanderthals and the elderly got used to consuming starchy foods as early as 100,000 years ago, which is much earlier than previously thought.

“We think we’re seeing evidence of some really ancient behavior that may have been part of encephalization – or the growth of the human brain,” said Harvard University researcher Christina Warinner. “It’s evidence of a new source of food that early humans were able to tap into in the form of roots, starchy vegetables, and seeds.”

The oral microbiome is a community of microorganisms in the mouth. They protect against diseases and promote health.

The results are part of a seven-year study in which more than 50 international scientists collaborated.

They reconstructed the oral microbiomes of Neanderthals, primates, and humans, including a 100,000-year-old Neanderthal, in what is believed to be the oldest oral microbiome ever sequenced.

The scientists analyzed the fossilized dental plaque of modern humans and Neanderthals, then compared them to chimpanzees and gorillas, humans’ closest primate relatives, and howler monkeys, a more distant relative.

Billions of DNA fragments preserved in the fossilized plaque were genetically analyzed to reconstruct their genomes.

The researchers were surprised to find strains of oral bacteria that are specifically designed to break down starch. These bacteria of the genus Streptococcus have the unique ability to capture starch-digestible enzymes from human saliva and feed themselves. The genetic machinery by which they do this is only active when starch is part of the normal diet.

The Neanderthals and the ancient people had these strength-adjusted strains in their dental plaque, but most primates had almost none.

“It appears to be a very human-specific evolutionary trait that our Streptococcus acquired the ability to do,” Warinner said in a Harvard press release.

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The results were published in the Proceedings of the National Academy of Sciences on May 10.

Researchers said the finding makes sense because starch-rich foods like underground roots, tubers like potatoes, nuts and seeds are important and reliable sources of food for hunter-gatherer societies around the world.

The human brain needs glucose as a source of nutrients, and meat alone isn’t enough, Warinner said. Starch makes up about 60% of the calories for humans worldwide.

“Availability is much more predictable for tropical hunters and gatherers throughout the season,” said study co-author Richard Wrangham, Ruth B. Moore professor of biological anthropology at Harvard. “This new data makes all sense to me and confirms the newer view about Neanderthals that their diet was more Sapien-like than expected.” [meaning] starchy and cooked. “

The research also identified 10 groups of bacteria that have been part of the oral microbiome of humans and primates for more than 40 million years and are still shared today. Little is known about them.

The oral microbiome of Neanderthals and modern humans was almost indistinguishable. The study looks at the ability to analyze the tiny microbes that live in the human body.

“It shows that our microbiome encodes valuable information about our own development that sometimes gives us clues about things that otherwise leave no trace at all,” said Warinner.