A new study shows that people who struggle to reduce their intake of carbohydrate foods are “guilty” of having ancient DNA still lurking in them, reports UPI.
In our saliva, we have copies of the gene for amylase (AMY1), which helps break down starch in the mouth – the first step in digesting carbohydrate foods such as bread, sweets and pasta, say researchers, BTA reported.
The AMY1 gene is normally produced in the pancreas, but its duplication has allowed it to develop salivary specificity. This has led to its secretion by the salivary gland as well.
The salivary duplication of this gene probably occurred as early as more than 800,000 years ago, long before the advent of agriculture, and helped shape the human adaptation to starchy foods, the researchers say.
Amylase is an enzyme that breaks down starch into glucose and gives bread its characteristic flavor, the researchers explained. It is the reason that food that has a lot of starch but little sugar – like rice and potatoes – starts to taste sweet after a long chewing – because amylase starts to break down the starch into sugar.
“The idea is that the more amylase genes you have, the more amylase you make and the more starch you digest efficiently,” says researcher Omer Gökchumen, a professor of biological sciences at the University at Buffalo.
For the purposes of the study, scientists analyzed the genetics of 68 ancient human bodies, including a man who lived 45,000 years ago in Siberia.
They found that even before the advent of agriculture, hunter-gatherers carried an average of four to eight copies of AMY1 in their genetic makeup, suggesting that humans had already adapted to eating starchy foods long before they began to they grow wheat and potatoes.
Duplications of the AMY1 gene have also been found in our ancient ancestors such as Neanderthals and Denisovans, the researchers added.
“This suggests that the AMY1 gene first duplicated more than 800,000 years ago, long before humans split from Neanderthals and much longer than previously thought,” says researcher Kim Kwondo, a postdoctoral fellow in the Genomics Laboratory Jackson Medicine.
These initial duplications of the AMY1 gene “allowed humans to adapt to changing diets, as starch consumption increased dramatically with the advent of new technologies and lifestyles,” says Gökkumen.
As humans spread around the world, flexibility in AMY1 copy number allowed them to adapt to new diets depending on their surroundings, the researchers said.
Agriculture has further altered human genetics. Over the past 4,000 years, European farmers have seen a sharp increase in the average copy number of AMY1, likely due to their starch-rich diet.
“People with a higher number of AMY1 copies digested starch more efficiently and had more offspring,” says Gökkumen, adding: “Their lines ended up doing better over a long evolutionary time period than those with lower copy number by spreading the increased copy number of AMY1.”
The new research was published Thursday in the journal Science.
This research could have practical, real-world implications for modern-day people suffering from obesity and type 2 diabetes, the researchers said. “Given the key role of AMY1 copy number variation in human evolution, this genetic variation provides an exciting opportunity to investigate its impact on metabolic health and to unravel the mechanisms involved in starch uptake and glucose metabolism.” said researcher Feiza Yilmaz, an associate scientist in computing at The Jackson Laboratory. “Future research could reveal its exact impact and timing, providing critical insights into genetics, nutrition, and health,” Yılmuz summarizes.