PERUVIAN ANDES — Indigenous Andeans in Peru exhibit the highest number of salivary amylase gene copies among all studied global populations, a trait linked to natural selection following potato domestication approximately 10,000 years ago. These individuals possess an average of 10 copies of the amylase gene, while the global average is seven.
Human saliva contains amylase enzymes that break down complex starches into simple sugars. Individuals with a higher number of amylase genes had a 1.24 percent greater probability of survival and reproduction compared to those with fewer copies. Omer Gokcumen, a professor of biological sciences at the University of Buffalo, noted the advantage would have compounded over generations.
Ancient populations in the Andes developed adaptations for high-altitude living and digesting new foods starting around 12,000 years ago. Previous genomic analyses of Peruvians with Indigenous South American ancestry indicated selection for an intestinal starch digestion enzyme. Researchers mapped salivary amylase gene copy numbers using genome data from 3,723 individuals across 85 global populations.
The Akimel O'odham people in southern Arizona and northern Mexico also exhibited high average numbers of salivary amylase genes. Researchers could not test for signs of natural selection in the Akimel O'odham sample due to an insufficient number of individuals. Charles Lee, a human genomics expert, said, "The high copy numbers in the Akimel O'odham samples suggests that different Indigenous American groups may have developed high amylase copy numbers in different ways, depending on their diets."
Omer Gokcumen said, "The strong survival and reproductive advantage suggests either a substantial number of babies did not survive because the pregnancies were not successful, or people with more gene copies have more babies. It's actually a life or death kind of situation." The specific functional advantage of increased salivary amylase copies is currently unknown. Researchers are investigating whether higher amylase gene copy numbers relate to the microbiome, metabolism, the immune system, or increased calorie extraction from cooked potatoes.
No independent assessment of Indigenous Andeans’s claims was available.