Potatoes may have given Indigenous Andeans a digestive superpower
A new study suggests that the rise of potatoes in the Andes may have left a lasting mark on human DNA, with Indigenous Peruvians carrying exceptionally high numbers of a starch-digestion gene.
The rise of potatoes in the Andes appears to have had a lasting impact on human evolution. For thousands of years, potatoes have been a central part of life in the Andes, with Indigenous Andean communities domesticating the crop and turning it into a dietary staple long before it spread around the world.
Indigenous people in Peru today carry more copies of a gene involved in starch digestion than any other known population. A recent study co-led by researchers at UCLA and the University at Buffalo suggests that natural selection began favoring Indigenous Andeans with especially high numbers of the salivary amylase gene, known as *AMY1*, around the same period that potatoes became established in the Andean highlands roughly 6,000 to 10,000 years ago.
## A Genetic Advantage for Digesting Starch
People who carry more copies of *AMY1* generally produce greater amounts of the amylase enzyme in their saliva and are believed to process starch more efficiently. This genetic advantage may have given Indigenous Andeans a survival or reproductive advantage, particularly in the high-altitude Andes where food resources can be limited.
The researchers collected DNA from Peruvian Andean Quechua speakers and compared those samples with genomic databases containing thousands of DNA samples from dozens of present-day human populations. They found that Indigenous people living in Peru today carry an average of 10 *AMY1* copies, approximately two to four more copies than any of the other 83 populations examined in the study.
## How Potato Farming Shaped Andean Evolution
The ancestors of Indigenous Andeans already possessed different numbers of *AMY1* copies before settling in the highlands and domesticating potatoes. However, once potatoes became an important food source, people with higher *AMY1* copy numbers appear to have gained an evolutionary advantage. The researchers estimated that beginning about 10,000 years ago, people with roughly 10 or more copies had a 1.24% survival or reproductive advantage per generation.
Over many generations, this process produced a striking difference. Indigenous people living in Peru today carry an average of 10 *AMY1* copies, compared with six among the Maya, an Indigenous population in Mexico that shares evolutionary history with Andean peoples but does not have a tradition of potato farming.
## A Potato Farming Signature in Human DNA
The researchers also compared Indigenous Peruvians with the Maya, and found that the difference in *AMY1* copy numbers supported the idea that potato cultivation played an important role in shaping Andean evolution. However, they had to rule out another major event in Indigenous American history: the severe population bottleneck that occurred following European contact in the 15th century.
Using state-of-the-art ultra-long DNA sequencing technologies together with newly available comparative datasets, the team found that high *AMY1* copy numbers had already become more common in the Andes several thousand years before Europeans arrived. This timing supports the conclusion that natural selection associated with diet, rather than the later population collapse, was responsible for the genetic pattern seen today.
## What Ancient Potatoes Reveal About Human Adaptation
The findings of this study could encourage broader research into human populations living at high elevations, where people face challenges that extend beyond low oxygen. Daily life can also involve limited food resources along with intense exposure to cold temperatures and ultraviolet rays.
The research also raises a much broader question about how humans may continue adapting to modern diets. For many people today, foods and cuisines from around the world are more accessible than ever, yet genetic adaptation remains part of the human story.
| Population | Average *AMY1* copies | | --- | --- | | Indigenous Peruvians | 10 | | Maya | 6 | | Other 83 populations | 6-8 |
Note: The table above shows the average number of *AMY1* copies in different populations, as reported in the study.
