Marcella La Cioppa If you've ever had trouble reducing your carb intake, an ancient gene may be to blame.
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A recent study led by the University of Buffalo, with collaboration from the Jackson Laboratory, shows our preference for carbs could be evolutionary and go back as far as more than 800,000 years.
It has long been known that humans carry multiple copies of a gene that allows us to begin breaking down complex carbohydrates in starches right in our mouths—an essential first step in metabolizing starchy foods like bread and pasta. But when and how this gene expanded has been the major challenge facing researchers in explaining its evolution.
Now, a landmark study headed by UB and Jackson Laboratory (JAX) reveals that the copy number expansion of the gene, called the salivary amylase gene (AMY1), not only played a role in shaping human adaptation to starch-rich diets but likely occurred more than 800,000 years ago, long before the dawn of agriculture.
The study
This research points out the AMY1 gene as the key to the efficient digestion of carbohydrates. The gene encodes a specific enzyme called salivary amylase, which begins to degrade starches immediately upon entering the mouth. Individuals possessing a higher number of copies of the AMY1 gene had better capabilities of starch digestion, enabling them to receive more energy from starchy foods-an attribute that may have provided important evolutionary advantages to early humans.
This preference for carbohydrates most likely began with pre-agricultural hunter-gatherers, already carrying a high number of AMY1 copies per cell, thus easily adapting them to starch-rich diets long before farming practices developed.
This ability was a survival and reproductive advantage for both Neanderthals and the ancestors of modern humans. Individuals who were able to digest starch more efficiently would have left more descendants who carried these genetic traits.
The idea is simple: the more amylase genes you have, the more amylase your body produces, and the more starch you can digest efficiently.
According to researchers, amylase doesn’t just break down starch into glucose; it also magnifies the flavor of bread.
Advanced genome mapping techniques
By applying optical genome mapping and long-read sequencing, Gokcumen and colleagues were able to gain further insight into the evolution of those AMY1 gene duplications. This really cutting-edge methodology enabled the investigators to map the AMY1 gene region in great detail.
This makes it difficult or impossible for traditional short-read sequencing methods to distinguish individual gene copies within the highly similar sequences. Long-read sequencing allowed the authors, for the first time in modern humans, to resolve this problem and provide a sharper view of how AMY1 duplications evolved.
Source: University of Buffalo
