FARMINGTON, USA – A new study published Thursday in Science suggests that the human love for carbohydrates may have deep evolutionary roots, long predating the advent of agriculture or even modern humans.
The findings challenge earlier assumptions about early human diets, which have often been characterized as protein-heavy, focused on large game like mammoths.
Instead, this research points to an ancient affinity for starch-rich foods that could have played a crucial role in human evolution.
Researchers at The Jackson Laboratory in Connecticut and the University of Buffalo analyzed the genomes of 68 ancient humans, looking specifically at a gene called AMY1.
This gene produces the enzyme amylase, which breaks down starches into simple sugars in the mouth.
The study found that ancient humans, long before the rise of farming, had multiple copies of the AMY1 gene, enabling them to digest starches more effectively.
“The main question that we were trying to answer was, when did this duplication occur?” said Feyza Yilmaz, associate computational scientist and lead author of the study.
“We wanted to understand whether it’s an occurrence that corresponds to the advent of agriculture. This is … a hot question.”
Long Before Agriculture
The team’s analysis showed that as far back as 45,000 years ago, hunter-gatherers, who existed well before the domestication of crops, had an average of four to eight copies of the AMY1 gene.
This suggests that Homo sapiens had been consuming and benefiting from starch-heavy diets long before they began cultivating crops like wheat, rice, and potatoes.
The study also uncovered that the gene’s duplication was present not only in early Homo sapiens but also in Neanderthals and Denisovans, suggesting that this genetic trait existed in a common ancestor of these human lineages as far back as 800,000 years ago.
This evolutionary advantage likely gave ancient humans the ability to adapt to different environments, especially as they encountered new and varied food sources, many of which were rich in starch.
The gene duplication provided a genetic opportunity that enhanced their ability to digest these foods and obtain more energy from them, which may have been critical for survival and brain development.
Carbs and Brain Development
The study’s findings lend support to the theory that it was carbohydrates, not proteins, that provided the essential energy needed to fuel the growth of the human brain over time.
Taylor Hermes, an anthropology professor at the University of Arkansas, noted that the research bolsters the idea that starches were a key component in brain development.
“The increased copy number of the amylase gene, which results in a greater ability to break down starch, may have emerged hundreds of thousands of years before Neanderthals or Denisovans,” he said.
This insight could help explain the rapid brain growth observed in early humans, providing a critical energy source that enabled humans to outpace other species in cognitive development.
Timing and Evolution
The study also showed that the number of AMY1 gene copies increased sharply in the last 4,000 years, coinciding with the shift from a hunter-gatherer lifestyle to one focused on agriculture.
This natural selection may have favoured individuals who could better process starch-rich grains and tubers, further embedding the importance of carbohydrates in human diets.
“This study’s genomic sleuthing is helping to finally time stamp some of those major milestones,” said Christina Warinner, an anthropologist at Harvard University.
“We know that dietary shifts 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 daunting.”
The findings represent a significant step forward in understanding how diet shaped human evolution, showing that humanity’s relationship with carbohydrates stretches much further back than previously thought.
