The next time you are tempted by a bowl of mashed potatoes, creamy pasta, or a warm slice of bread, go easy on yourself.
The constant struggle to resist carbs could, very well, be traced to ancient DNA, a new study by researchers at the University at Buffalo (UB) and the Jackson Laboratory (JAX) has revealed.
The reason behind the irresistible appeal of starch is mostly likely rooted in a duplication of the salivary amylase gene (AMY1), dating back as far as 800,000 years - long before the advent of farming.
Amylase is an enzyme that not only breaks down starch into glucose but also gives bread its taste.
The early duplication AMY1 gene set the stage for the wide genetic variation that still exists today, influencing how effectively humans digest starchy foods, the study noted.
Corresponding author of the study, Omer Gokcumen, PhD, professor in the Department of Biological Sciences, within the UB College of Arts and Sciences, stated, “The idea is that the more amylase genes you have, the more amylase you can produce and the more starch you can digest effectively.”
Findings Of The Study
The study revealed that pre-agricultural hunter-gatherers already had an average of four to eight AMY1 copies per diploid cell, suggesting that humans were already walking around Eurasia with a wide variety of high AMY1 copy numbers well before they started domesticating plants and eating excess amounts of starch.
It also found that AMY1 gene duplications occurred in Neanderthals and Denisovans.
“This suggests that the AMY1 gene may have first duplicated more than 800,000 years ago, well before humans split from Neanderthals and much further back than previously thought,” says Kwondo Kim, one of the lead authors on this study from the Lee Lab at JAX.
Gokcumen added, “The initial duplications in our genomes laid the groundwork for significant variation in the amylase region, allowing humans to adapt to shifting diets as starch consumption rose dramatically with the advent of new technologies and lifestyles.”
Impact Of Agriculture
Over the past 4,000 years, European farmers saw an increase in average AMY1 gene copies, likely driven by starch-rich diets.
The findings are backed by another study by the University of California, Berkeley, which revealed that humans in Europe expanded their average number of AMY1 copies from four to seven over the last 12,000 years.
“Given the key role of AMY1 copy number variation in human evolution, this genetic variation presents an exciting opportunity to explore its impact on metabolic health and uncover the mechanisms involved in starch digestion and glucose metabolism,” said Feyza Yilmaz, an associate computational scientist at JAX and a lead author of the study.
“Future research could reveal its precise effects and timing of selection, providing critical insights into genetics, nutrition, and health.”
Previous research by Gokcumen showed that domesticated animals living alongside humans, such as dogs and pigs, also have higher amylase gene copy numbers compared to animals not reliant on starch-heavy diets.
“Individuals with higher AMY1 copy numbers were likely digesting starch more efficiently and having more offspring,” Gokcumen stated.
“Their lineages ultimately fared better over a long evolutionary timeframe than those with lower copy numbers, propagating the number of the AMY1 copies.”
