From warm, fluffy bread to crispy, indulgent fries, carbohydrates are both a common craving and a vital component of the human diet. Despite their importance, craving carbs may cause us to feel guilty and unhealthy, as excessive consumption can increase cholesterol levels while placing a burden on metabolism. We might guess that these cravings began after humans entered the agricultural era, but recent studies show that our love of starchy foods developed before the age of agriculture and even the emergence of modern humans.
Carbohydrates are essential macronutrients composed of sugars, starches, and fibers. They are found in a variety of foods, from fruits and vegetables to candy and pastries. When carbohydrates enter the mouth, a specific enzyme called amylase is released by salivary glands, which initiates the process of carbohydrate metabolism and gives carbs such as bread a sweet aftertaste. Having more amylase genes allows for greater amylase production, enabling efficient starch digestion.
Researchers from The Jackson Laboratory and the University of Buffalo recently conducted a study that focused on the salivary amylase gene (AMY1) in early humans. The researchers analyzed the genomes of 68 prehistoric humans and found that pre-agricultural hunter-gatherers already possessed four to eight copies of AMY1. The study also found that the duplication of AMY1 existed in two archaic human species, the Neanderthals and Denisovans, which indicates that the first duplication occurred more than 800,000 years ago. The initial duplication might have occurred randomly, but it gave early humans an advantage in adapting to new environments and diets. Over the past 4,000 years, as humans have consumed more grains and starch-rich foods, the number of AMY1 copies has also increased significantly. According to the study’s author Omer Gokcumen, “Individuals with higher AMY1 copy numbers were likely digesting starch more efficiently and having more offspring.” Thus, the AMY1 genes were easily passed down to the next generation, resulting in the preservation of this gene type in humans.
Another study published in Nature magazine found that the average number of AMY1 genes in Europeans increased from four to seven in the past 12,000 years, corresponding to the rise of agriculture. Thus, the development of agricultural society created the need for more AMY1, but it is possible that random AMY1 duplications from 800,000 years ago were simply the first ripple in a lake, leading to the shift that made carbs a central part of our diet.