Study Links Ancient Potato Farming to Genetic Evolution in Indigenous Andes

New research co-led by UCLA and the University at Buffalo suggests that the historical reliance on potatoes in the Andes may have influenced human evolution. Indigenous Andeans have developed a unique genetic adaptation that enhances starch digestion, evidenced by their higher copies of the salivary amylase gene known as AMY1.

The findings, published in the journal Nature Communications, indicate that natural selection has favored Indigenous Andeans with higher numbers of AMY1 copies, a shift occurring between 6,000 to 10,000 years ago, coinciding with the domestication of potatoes in the highlands.

A Genetic Advantage for Digesting Starch

Abigail Bigham, an associate professor of anthropology at UCLA, highlighted that individuals with more AMY1 copies can produce greater amounts of the amylase enzyme, which aids in starch digestion. Bigham’s team collected DNA samples from Peruvian Andean Quechua speakers, comparing them against global genomic databases to investigate differences in AMY1 copy numbers.

“The high-altitude Andes are known for being a rich region for understanding human evolutionary adaptation,” Bigham stated. “This new research highlights how the Andes are useful for understanding human evolutionary adaptation to other selective environmental pressures like diet.”

Co-corresponding author Omer Gokcumen from the University at Buffalo noted that earlier findings indicated the first AMY1 duplications occurred in humans over 800,000 years ago. He emphasized the strength of the evidence linking natural selection to diet in this context.

How Potato Farming Shaped Andean Evolution

Before the advent of potato farming, Indigenous Andeans exhibited varying numbers of AMY1 copies. However, as potatoes became a significant food source, individuals with higher AMY1 copies gained a survival advantage. The researchers estimated around 10,000 years ago, those with 10 or more copies enjoyed a 1.24% reproductive advantage per generation.

“Evolution is chiseling a sculpture, not constructing a building,” Gokcumen remarked. He explained that this process saw populations with fewer AMY1 copies gradually eliminated over time, culminating in today’s Indigenous Peruvians averaging about 10 copies, surpassing the average found in other studied populations.

A Potato Farming Signature in Human DNA

In a comparative analysis, the research team found that Indigenous Peruvians carry an average of 10 AMY1 copies, noticeably more than the Maya, an Indigenous group from Mexico, who average six. This difference supported the hypothesis that potato cultivation contributed significantly to genetic variation.

The researchers faced a challenge in ruling out the impact of the dramatic population decline following European contact in the 15th century, which could have altered genetic diversity. However, their analysis using advanced DNA sequencing confirmed that the increased AMY1 copy numbers in the Andes predated this population bottleneck.

Implications for Human Adaptation

Bigham expressed that the findings encourage further research into high-altitude human populations facing various environmental challenges. These results also prompt questions about ongoing human adaptation to modern diets, as genetic evolution continues to play a role alongside increasing access to diverse foods.

“I think this research shows that human populations have responded and evolved to changing food conditions within the last 10,000 years,” Bigham concluded, affirming that contemporary metabolic pathways are not solely a legacy of the Paleolithic past.

This research was supported by the National Science Foundation, National Institutes of Health, and the Leakey Foundation, with contributions from researchers at several institutions, including the University of Kansas and Syracuse University.