Here’s what you’ll learn when you read this story:

• Salivary amylase genes, or AMY1, are known to aid in starch digestion, and several copies can be found in human DNA.
• A new study found that indigenous Andean populations had two to four more copies of AMY1 compared to other human populations, driven by the staple item in their diet: potatoes.
• This discovery is a rare glimpse into how diet can shape humanity down to the genetic level.

When it comes to evolution, the name of the game is adaptation. Slowly, over time, natural selection favors certain traits over others. Sometimes these differences can be subtle—whether a bird’s wings are loud when they flap or deathly silent, for example—or incredibly obvious, such as Mexican cavefish who’ve lost their eyes completely. These differences can also be seen within the same species, including Homo sapiens.

Genetic differences can arise from a number of causes. In a new study in the journal Nature Communications, an international team of scientists led by researchers at University of California Los Angeles (UCLA) and the University of Buffalo focused on how diet can cause these differences, finding that the DNA of indigenous Andean populations included a remarkably high number of salivary amylase genes, or AMY1—a perfect adaption for the region’s dietary staple: the starchy potato.

“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,” UCLA’s Abigail Bigham, a co-author of the study, said in a press statement. “This new research highlights how the Andes are useful for understanding human evolutionary adaptation to other selective environmental pressures like diet.”

Although potatoes are commonly associated with places like Ireland or Idaho, the tuber actually originates from the Andes, with the first verified archaeological discovery of potatoes in the region dating to at least 4,000 years ago, though its cultivation actually began likely between 6,000 and 10,000 years ago. It was one of the main energy sources for the Inca Empire, who regularly freeze-dried potatoes during cold nights in the high elevation of the Andes to create chuño, which in the native Quechua language literally means “frozen potato.” Because the potato was so central to indigenous Andean communities for so long, this humble vegetable eventually began to rewrite the genetic code of the local population.

As part of the study, Bigham and her team collected DNA samples from Quechua speakers and compared them to genomic databases spanning dozens of different human populations. What they found is that they contained an outsized number of AMY1, a gene that’s known to help in starch digestion. Compared to 83 other human populations, the Andean group contained two to four more copies of AMY1.

A 2024 study found that AMY1 copy number variation likely began in hominins around 800,000 years ago, leading to a common three-copy haplotype in humans. Since ancient humans already carried high AMY1 copy numbers as far back as 45,000 years ago—well before the peopling of the Americas—the first Andeans would have already carried multiple AMY1 copies. However, some carried more copies of AMY1 than others, and that would have given them an evolutionary advantage. According to the authors, someone living 10,000 years ago with 10 copies of AMY1 had a “1.24% survival or reproductive advantage per generation.”

“Evolution is chiseling a sculpture, not constructing a building,” the University of Buffalo’s Omer Gokcumen, co-author of the new research and senior author of the 2024 study, said in a press statement. “It’s not as if Indigenous Andeans gained additional AMY1 copies once they started eating potatoes. Instead, those with lower copy numbers were eliminated from the population over time, perhaps because they had fewer offspring, and the ones with the higher copy numbers remained.”

Although today potatoes are eaten all over the world, Bigham says that this isn’t an evolutionary machine that’s slowed down with passing millennia. “Our metabolic pathways are not simply a product of that Paleolithic past,” she says.

In other words, our bodies will continue to adapt to the very foods that sustain us.