Thank Neanderthals’ diet for your big brain
A new study could dramatically alter our perception of Neanderthals as brutish meat eaters.
The study examined bacteria collected from Neanderthal teeth and found that our ancient cousins ate so many roots, nuts, or other starchy foods that they radically changed the types of bacteria in their mouths.
Although this might not come across as significant, the findings suggest our ancestors started eating lots of starch at least 600,000 years ago - right around the time that they needed more sugars to expand their brains.
The work suggests that ancestors of both humans and Neanderthals were cooking starchy foods at least 600,000 years ago, and that they had already adapted to eating starchy plants long before the invention of agriculture 10,000 years ago, according to Harvard University evolutionary biologist Rachel Carmody.
Our ancestors’ brains doubled in size between 2 million and 700,000 years ago.
Though researchers have long attributed brain growth to the use of stone tools and cooperative hunting style of early humans that let them eat more energy-rich meat, how this actually worked has long puzzled researchers.
“For human ancestors to efficiently grow a bigger brain, they needed energy dense foods containing glucose” - a type of sugar - molecular archaeologist Christina Warinner of Harvard and the Max Planck Institute for the Science of Human History said. “Meat is not a good source of glucose.”
But, the starch-filled plants collected by hunter-gatherers do act as an excellent source of glucose.
By studying the DNA of bacteria stuck to the teeth of Neanderthals, chimps, gorillas, howler monkeys, and preagricultural humans that lived more than 10,000 years ago, researchers found that the bacteria in preagricultural humans and Neanderthals strongly resembled each other.
In particular, they found an unusual group of Streptococcus bacteria in their mouths, which has a special ability to free sugars from starchy foods by binding to an enzyme in human saliva called amylase.
The strep bacteria that consume sugar were found on Neanderthal and ancient modern human teeth, but not on chimps, which the researchers said shows they were eating more starchy foods.
It also suggests they inherited these microbes from their common ancestor, who lived more than 600,000 years ago.
Although evidence of Neanderthals eating grasses, tubers, and cooked barley has already been found, this new study indicates that they ate so much starch that it altered the composition of the microbiomes in their mouths.
“This pushes the importance of starch in the diet further back in time” to when human brains were still growing, Warinner said.
Because the amylase enzyme is more efficient at digesting cooked starch rather than raw starch, the research also suggests that cooking was common by 600,000 years ago, Carmody said.