Indigenous peoples in the Andes have been eating potatoes longer than anyone else, having domesticated the humble spud 10,000 years ago. That history of potato-munching appears to have altered the physiology of people living in the region.
Researchers have shown that the descendants of these indigenous peoples have more genes for starch digestion — which is essential for handling a potato-rich diet — than almost any other group on Earth.
The new study was published in Nature Communications.
Why the Andes Region Helps Us Understand Human Evolution
The new study was led by Abigail Bigham, an anthropologist at the University of California, Los Angeles, who studies populations living at high altitudes in the Peruvian Andes and the Himalayan region of Nepal.
Bigham’s team sampled DNA from people in the Andes who speak the indigenous Quechua language, and compared it with samples taken from 83 other populations around the world.
“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 Bigham in a statement. “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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Analyzing Amylase’s Evolutionary Advantage
Bigham’s team focused on a salivary amylase gene, AMY1, in their samples. People with many copies of the AMY1 gene produce more amylase, which is thought to enhance starch breakdown.
Ancient indigenous peoples in the Andes already had AMY1 in their genomes when they first started cultivating potatoes. But there was a natural range in the population at the time. Once potatoes became an essential part of their diet, those with more copies of the genes that enabled them to extract more nutrition from them had a distinct evolutionary advantage.
This boon meant that people with 10 or more copies of AMY1 in their genome had a 1.24 percent reproductive or survival advantage per generation over those without, the researchers concluded.
“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,” said Omer Gokcumen, an evolutionary anthropologist at the University at Buffalo and co-author of the new study in the press release.
This gradual specialization led to the gene landscape we see today, in which the Quechua-speaking people analyzed in the study had an average of 10 AMY1 copies. That’s between two and four more copies than any other group measured.
How Diets Impact Our DNA
The study found that these gene copies rose rapidly in indigenous populations. This was an important finding, as the rise in AMY1 could have been attributed to the rapid population decline that occurred after European colonialism devastated indigenous populations in the area. This type of decline can produce a “bottleneck” effect that promotes rare genes, but Bigham’s team showed this wasn’t a contributor to the high number of AMY1 copies in their samples.
These findings add to the study of how diet affects human DNA. Modern diets are more global than ever before.
“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,” said Bigham.
“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,” she concluded.
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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
