A study published in the journal Science reveals that humanity's modern-day adoration for carbohydrates may actually predate the emergence of Neanderthals. Researchers from the University at Buffalo and The Jackson Laboratory discovered that ancient humans possessed multiple copies of the AMY1 gene, which enables the digestion of starches.
"Our findings indicate that the duplication of the AMY1 gene existed in the genomes of Neanderthals and Denisovans," said Dr. Omer Gokcumen, a professor of evolutionary anthropology at the University at Buffalo, according to a report by CNN. "This allowed humans to adapt to shifting diets as starch consumption rose dramatically with new technologies and lifestyles."
The AMY1 gene codes for salivary amylase, an enzyme that converts complex carbohydrates into simple sugars. The presence of multiple copies of this gene suggests that humans have been primed to enjoy carbohydrate-rich foods for much longer than previously thought, revealing clues about humanity's longstanding love affair with carbohydrates.
Further analysis of 68 ancient genomes showed that Neanderthals also seemed to have multiple duplications of the AMY1 gene, according to a report by Technology Networks. "This kind of genetic variation means that the tongues of both modern humans and Neanderthals were prepared for a carbohydrate-rich diet thousands of years before the agricultural revolution offered such a lifestyle," the report stated.
The researchers utilized optical genome mapping and long-read sequencing on the genomes of 98 participants recruited from distinct genetic populations. "We studied a diverse group of individuals," said Dr. Gokcumen, according to a report by Technology Networks. "In fact, the majority of our samples were non-European. This gave us a good snapshot of the 'common' variation in the amylase region across different populations."
Lead author Feyza Yilmaz, associate computational scientist at The Jackson Laboratory, explained the motivation behind the study. "The main question we were trying to answer was: when did this duplication occur? That's why we started studying ancient genomes," she said, according to Science.
The study revealed that pre-agricultural hunter-gatherers had an average of four to eight copies of the AMY1 gene per cell. "Almost all modern humans have several copies of the AMY1 gene, with the number varying from person to person," noted the New York Post. The number of AMY1 gene copies was highest in the most recent people, having increased sharply in the last 4,000 years, likely favored by natural selection as humans adapted to starch-rich diets.
"People with higher AMY1 copy numbers were likely digesting starch more efficiently and having more children," said Gokcumen, according to a report by The Sun.
The findings challenge the stereotype that ancient humans feasted primarily on meat. "Recent archaeological findings have cast doubt on the widely held belief that prehistoric people were primarily meat eaters, suggesting they developed a taste for carbohydrates long ago," reported Science. The findings suggest that Homo sapiens had a taste for starch long before the domestication of crops shaped the human diet.
Taylor Hermes, assistant professor in the Department of Anthropology at the University of Arkansas, who was not involved in the research, commented on the significance of the findings. "The authors' finding that a greater number of AMY1 gene copies, which leads to a greater capacity to break down starch, may have arisen hundreds of thousands of years before Neanderthals or Denisovans gives more credit to the idea that starches were metabolized into simple sugars to fuel the rapid brain development during human evolution," he said, according to the New York Post.
Despite the comprehensive analysis, the researchers acknowledged limitations regarding the ancient DNA samples. "One caveat is that for the analysis of ancient genomes, we were limited mostly to European samples due to their availability," explained Dr. Gokcumen, according to a report by Technology Networks. "How this recent history—particularly the last 10 to 5 thousand years—differs in other parts of the world, particularly in terms of dietary changes and the impact on amylase gene variation, remains an open and exciting area of study."
The study provides compelling evidence that humans developed the molecular machinery to convert difficult-to-digest starches into accessible sugars long before agriculture. "This ability, upon the dawn of the agricultural revolution, would have benefited these individuals and their offspring," reported Technology Networks.
Christina Warinner, associate professor at Harvard University, highlighted the challenges in reconstructing ancient diets. "We know that changes in diet have played a central role in human evolution... but reconstructing these events that took place thousands, hundreds of thousands, and even millions of years ago is overwhelming," she stated, according to a report by CNN Spanish.
The researchers are hopeful that further studies will shed more light on how dietary changes influenced human evolution. "Although I think it's justified to conduct more tests with higher quality ancient human genomes, I was surprised that the authors were able to detect multiple copies of amylase genes in Neanderthal and Denisovan genomes that had already been published earlier," Hermes added, as reported by the New York Post. "This demonstrates the value of continuing to explore the genomes of our human ancestors for important medical and physiological records."
The article was written with the assistance of a news analysis system.