A recent study has found that the duplication of a specific gene may have played a key role in how humans adapted to eating starchy foods. Getty Images
Recent research suggests that our enduring love for carbohydrates may date back to before modern humans even existed. Traditionally, many believed that our ancient ancestors thrived on a diet heavy in protein, primarily from hunting large mammals. This perception supported the idea that a high protein intake was essential for the development of our larger brains. However, new findings challenge this view, indicating that early humans likely had a taste for carbohydrates long before agriculture began.
Recent archaeological evidence shows that ancient humans roasted starchy foods, such as tubers. This information comes from studying bacteria found in ancient teeth, which provides insight into the diets of our ancestors. The study published in the journal Science highlights the first hereditary evidence supporting early carbohydrate-rich diets.
Researchers focused on a gene called AMY1, responsible for breaking down starch into simpler sugars, making it easier for our bodies to use as energy. The findings reveal that this gene likely duplicated many years ago, even before modern humans, or even Neanderthals, emerged as distinct species. The study involved analyzing the genomes of 68 ancient humans, revealing that hunter-gatherers from as far back as 45,000 years ago had multiple copies of the AMY1 gene, suggesting that they had already developed a preference for starchy foods before agriculture reshaped human diets.
Feyza Yilmaz, the study’s lead author and a scientist at The Jackson Laboratory, emphasized the significance of understanding when this duplication occurred. Past research indicated a connection between the number of AMY1 copies and the amount of amylase enzyme produced in saliva, which is crucial for starch digestion. The team wanted to determine if this gene's duplication coincided with the rise of agriculture, a critical question in the field.
In their analysis, they discovered that ancient hunter-gatherers possessed an average of four to eight copies of the AMY1 gene, which implies that they had a taste for carbohydrates long before farming began. This gene duplication was also found in the genomes of Neanderthals and Denisovans, indicating that the ability to digest starch was likely a trait inherited from a common ancestor that lived up to 800,000 years ago.
The initial duplication of the AMY1 gene probably occurred randomly. This duplication provided an evolutionary advantage for our ancestors, allowing them to adapt to diverse environments with carbohydrate-rich diets. Interestingly, the study noted that the number of AMY1 copies in human populations has significantly increased over the past 4,000 years, likely due to natural selection favoring those who could efficiently digest starch as they transitioned from hunter-gatherer lifestyles to farming.
The findings support the theory that carbohydrates, rather than proteins, might have fueled the growth of the human brain throughout evolution. Taylor Hermes, an assistant professor in anthropology, commented on the implications of the research, noting that the ability to digest starch could have contributed significantly to brain development.
Overall, this study provides vital evidence of how our genetic ability to process carbohydrates evolved, shedding light on humanity's longstanding relationship with starch. By tracing the history of this important gene, researchers are beginning to understand the pivotal role that dietary shifts have played in shaping our species.
