Research suggests that ancient DNA may be the reason you love carbohydrates, such as bread and potato chips.
The researchers found that the gene responsible for digesting starch in saliva may have mutated (a type of mutation that involves the production of one or more copies of a gene) for the first time more than 800,000 years ago, paving the way for the genetic change that shapes our diets today.
Experts have known for some time that humans carry multiple copies of the gene that enables the starch in complex carbohydrates — which also includes foods such as potatoes, rice and some fruits and vegetables — to break down in the mouth.
This provides the first step in digesting these foods, and the more copies of these genes people have, the better prepared they are to break down carbohydrates. However, it has been difficult for researchers to determine how and when the number of these genes expanded.
The new study by the University of Buffalo (UB) and The Jackson Laboratory (JAX) in the US found that duplication of the gene, known as the salivary amylase gene (AMY1), may not only have helped shape human adaptation to starchy foods, but may have occurred more than 800 years ago. A thousand years, long before the advent of agriculture.
According to researchers, amylase is an enzyme that not only breaks down starch into glucose, but also gives bread its flavor.
This explains why humans cannot resist starchy foods, such as potatoes, bread, pasta and rice, as well as baked goods, such as cakes and biscuits.
“The idea is that the more amylase genes you have, the more amylase you produce and the more starch you can digest effectively,” said study co-author Omar Jokomin, a professor in the Department of Biological Sciences in the College of Arts and Sciences at the University at Buffalo in New York.
By analyzing the genomes of 68 ancient humans, including a 45,000-year-old sample from Siberia, the researchers found that pre-agricultural hunter-gatherers already had duplicate copies of the gene.
This suggests that humans were already roaming Eurasia with a variety of these genes long before agriculture and eating excessive amounts of starch began.
The study also found that duplication of the AMY1 gene occurred in Neanderthals and Denisovans.
“This suggests that the AMY1 gene may have duplicated for the first time more than 800,000 years ago,” said Kwondo Kim, one of the lead authors of this study from Lee’s laboratory in Jacksonville. “The initial duplications in our genomes laid the foundation for significant divergence in the amylase region, allowing humans to adapt.” “With changing diets and starch consumption rising dramatically with the advent of new technologies and lifestyles.”
The study highlights that while early hunter-gatherers had multiple copies of the gene, European farmers saw an increase in the average number of AMY1 copies over the past 4,000 years, likely due to their starch-rich diets.
Source: Independent
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