Thousands of years of potato cultivation may have contributed to a genetic adaptation associated with starch digestion among Indigenous Andean populations, according to research published in Nature Communications.

The study, co-led by researchers from the University at Buffalo and the University of California, Los Angeles, examined AMY1 gene copy numbers using genomic data from 3,723 individuals across 85 populations.

AMY1 encodes salivary amylase, an enzyme that begins breaking down starch in the mouth. People with more copies of the gene tend to produce higher levels of the enzyme and are thought to digest starch more effectively.

The researchers found particularly high AMY1 copy numbers among Indigenous Peruvian Andean populations. A cohort of Quechua participants from Peru had a median of 10 copies, compared with a median of six among Maya participants from Mexico and a worldwide median of seven.

Peruvians from Lima and the Akimel O’odham, also known as the Pima, recorded the highest median AMY1 copy numbers among the populations included in the study.

The researchers also identified evidence of positive selection affecting a genetic variant associated with high AMY1 copy numbers. They dated the expansion of this variant among Peruvian Andean populations to approximately 10,000 years ago, broadly coinciding with the beginning of potato domestication in the region.

“Biologists have long suspected that different groups of humans have evolved genetic adaptations in response to their diets, but there are very few cases where the evidence is this strong,” said Omer Gokcumen, professor of biological sciences at the University at Buffalo and a co-corresponding author of the study.

The findings do not suggest that Andean populations developed additional AMY1 copies after they began cultivating potatoes. Instead, the researchers believe that people who already carried higher copy numbers gained a survival or reproductive advantage as starch-rich foods became more important to the regional diet.

The study estimated that people carrying approximately 10 or more AMY1 copies had a 1.24% survival or reproductive advantage per generation from around 10,000 years ago.

“Evolution is chiseling a sculpture, not constructing a building,” Gokcumen said. “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.”

Researchers compared the Peruvian Quechua population with Maya communities in Mexico because the two populations share aspects of their evolutionary history but have different agricultural traditions. Potatoes did not historically form the same central part of the Maya diet.

The comparison supported the case that the elevated AMY1 copy numbers in the Andes resulted from natural selection rather than genetic ancestry alone or population decline following European contact with the Americas.

However, the study does not establish that potatoes were the sole cause of the adaptation. Quinoa was also domesticated in the Andes, while maize was introduced to the region later. All three crops provided substantial quantities of starch.

The authors therefore describe potato consumption as a plausible explanation rather than a proven direct cause. They also caution that the wider biological effects of carrying additional AMY1 copies remain unclear.

Although higher copy numbers are associated with increased salivary amylase production, research into their effects on metabolism, health and the body’s response to starch has produced mixed results.

The findings nevertheless provide evidence that the transition from foraging to agriculture in the Andes placed evolutionary pressure on genes involved in starch digestion. They also underline the potato’s long-standing importance to the food systems and human history of the region.