Life in the Andes comes with limits. At high elevations, oxygen is thin, temperatures swing, and food has historically been scarce. When potatoes became a staple, they offered a dependable source of calories. Over time, they may have done more than that, shaping the biology of the people who relied on them.
A new study published in Nature Communications suggests potatoes helped reshape the human genome. Researchers found that Indigenous Andean populations carry unusually high numbers of copies of a gene linked to starch digestion, driven by natural selection after potatoes became a central part of the diet between about 6,000 and 10,000 years ago.
The gene, called AMY1, helps produce an enzyme that begins breaking down starch in the mouth. People vary widely in how many copies they carry, and in the Andes, higher copy numbers were linked to a measurable advantage. People in Peru carry an average of about 10 copies, more than any of the 83 populations analyzed, and those with more copies had about a 1.24 percent survival or reproductive advantage per generation.
“The high-altitude Andes are known for being a rich region for understanding human evolutionary adaptation — for instance, hypoxia, in which tissues do not get enough oxygen,” said study co-author Abigail Bigham in a press release. “This new research highlights how the Andes are useful for understanding human evolutionary adaptation to other selective environmental pressures like diet.”
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How a Potato-Based Diet Gave Some Andean Populations a Genetic Advantage
To understand how this pattern formed, researchers compared Andean populations with others that share ancestry but different food histories, including the Maya, who did not rely on potato farming in the same way. The Maya carried fewer copies of AMY1, pointing to long-term diet, not shared ancestry, as the key difference.
The advantage was small, but it added up. Individuals with more AMY1 copies processed starch more efficiently, giving them a slight edge in survival or reproduction that shifted the population over generations.
This wasn’t a case of new genetic changes appearing after potatoes were introduced. The variation already existed. As potatoes became more common, individuals with fewer copies became less common, while those with more copies were more likely to pass their genes on.
“Biologists have long suspected that different groups of humans have evolved genetic adaptations in response to their diets,” co-author Omer Gokcumen said in the press release, “but there are very few cases where the evidence is this strong.”
Sorting Long-Term Adaptation From a Sudden Population Collapse
The researchers also had to account for a major disruption. Following European contact in the 15th century, Indigenous populations across the Americas declined sharply due to disease, famine, and conflict. Events like this can reshape genetic variation, complicating efforts to separate long-term trends from more recent changes.
Using ultra-long DNA sequencing and large genomic datasets, the team found that higher AMY1 copy numbers had already become more common in the Andes thousands of years before Europeans arrived. That timing points to natural selection, not population collapse, as the primary driver.
What a Potato Diet Reveals About Human Evolution Today
The results show how closely diet and human biology are connected. The genome is not fixed. It can respond to changes in how people live and what they eat, even over relatively short evolutionary timescales.
They also challenge the idea that human metabolism is shaped only by ancient environments. Instead, the research suggests populations have continued to adapt to major changes in food production and availability.
“There are ideas out there like the paleo diet, which is adapted to the Paleolithic environment and says we’re not suited to eat foods that come post-domestication,” Bigham said. “But I think this research shows that human populations have responded and evolved to changing food conditions within the last 10,000 years. Our metabolic pathways are not simply a product of that Paleolithic past.”
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Article Sources
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- This article references information from a study published in Nature Communications: Rapid adaptive increase of amylase gene copy number in Indigenous Andeans
