A new study suggests that your love for carbohydrates like bread and pasta could be traced back to ancient DNA. Researchers from the University of Buffalo (UB) and the Jackson Laboratory (JAX) in the US have found evidence that humans may have developed the ability to digest starchy foods much earlier than previously thought—possibly even before farming began or humans split from Neanderthals.
A Gene That Shapes Our Diet
The study focuses on the starch-digesting salivary amylase gene (AMY1), which plays a key role in breaking down carbohydrates. This gene helps convert starch into glucose, the primary source of energy for the body. The more copies of the AMY1 gene a person has, the better they can digest starchy foods like bread, pasta, potatoes, and rice.
According to the study, the duplication of the AMY1 gene, which is a type of mutation that results in extra copies of a gene, may have occurred over 800,000 years ago. This discovery suggests that humans were already adapting to starch-rich diets long before the advent of agriculture.
Early Duplication of AMY1 Gene
Omer Gokcumen, a professor in the Department of Biological Sciences at UB and the study's co-author, explains, "The idea is that the more amylase genes you have, the more amylase you can produce, and the more starch you can digest effectively." The study found that the gene duplication responsible for starch digestion may have happened much earlier than once thought, laying the foundation for modern humans' ability to thrive on carbohydrate-rich diets.
Researchers analyzed the genomes of 68 ancient humans, including a 45,000-year-old specimen from Siberia. Their findings revealed that even pre-agricultural hunter-gatherers had multiple copies of the AMY1 gene, which enabled them to digest starchy foods effectively. This means that humans were already walking across Eurasia with the ability to digest carbohydrates long before they began farming and eating large quantities of starch.
Connection to Neanderthals and Denisovans
Interestingly, the study also found that Neanderthals and Denisovans—ancient human relatives—had similar duplications of the AMY1 gene. This suggests that the ability to digest starch was already present in human ancestors, predating the split between modern humans and these ancient relatives. The researchers believe that the first duplication of the AMY1 gene may have occurred more than 800,000 years ago, much earlier than previously thought.
One of the study's lead authors Kwondo Kim, from the Lee Lab at JAX, said, "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 on Modern Diets
The study also sheds light on how the number of AMY1 gene copies increased in European farmers over the last 4,000 years, likely in response to the growing consumption of starchy foods in their diets. These findings highlight the important role of ancient DNA in shaping modern human diets and how our genetic makeup has allowed us to adapt to new food sources over millennia.
By using genome mapping and sequencing, the researchers were able to detail the evolution of the AMY1 gene and how it has influenced our ability to digest carbohydrates. This study, published in the journal Science, offers new insights into how ancient genetic adaptations continue to affect our dietary preferences today.