The Quechua are a diverse set of indigenous peoples of the Andes and the direct heirs of the Inca Empire
Despite all of humanity’s successes as a species at the height of its capabilities, it is likely that we will never stop evolving. At least… in the Andes.
We already knew that the inhabitants of the Andes are special: we recently told ZAP that they can do it, without presenting any health problems.
Now, a new one, recently published in Nature Communicationsrevealed a previously unknown form that allows people living in the high reaches of the Andes continue to evolve — and the catalyst is surprisingly humble.
This population was one of the first to domesticate the now ubiquitous potatothousands of years ago, which may explain why their bodies show signs of a enhanced ability to digest this starch.
“The high-altitude Andes are known to be a very rich region for understanding human evolutionary adaptation — for example, hypoxia, a situation in which tissues do not receive enough oxygen”, says Abigail Bighamanthropologist at the University of California and corresponding author of the study.
“This new research shows how the Andes are also useful for understanding human evolutionary adaptation to other selective environmental pressureslike food”, adds the researcher, cited by Science Alert.
Evolution is a process that combines time with constant exposure to a selective pressureto which some organisms can respond better than others.
This may include extreme conditions, such as scorching heattotal absence of oxygen or dangerous levels of radiationbut also more subtle pressures, such as continuous exposure to small doses of toxins or the types of foods people depend on.
A few years ago, a team of researchers that included Bigham concluded that indigenous populations living in the Andes associated with starch digestionwhen compared to populations that adopted potatoes more recently.
Now, the team has expanded the research to include genomes from various parts of the world — and concluded that the Quechua peopleof highland Andean indigenous descent, appears to be better equipped to digest starch than almost any other population on Earth.
“Biologists have long suspected that different human groups evolved genetic adaptations in response to their diets”, says the evolutionary anthropologist Omer Gokcumenresearcher at the University at Buffalo and co-author of the study. “But there are very few cases where the evidence is so strong.”
The clue is in a gene called AMY1present in practically everyone in the world. This gene is involved in the production of amylasea salivary enzyme that helps break down starch at the very beginning of the digestive process — in the mouth.
As a general rule, each individual has between 2 and 20 copies of this gene per diploid cell; According to data from the new study, the global median is 7 copies.
After analyzing the genomes of 3,723 individuals from 85 populations around the world, researchers concluded that the Quechua indigenous people of Peru have a median of 10 gene copieswhich may have conferred a survival or reproduction advantage on 1.24% per generation.
“Evolution carves a sculpture; it doesn’t build a building,” explains Gokcumen.
“It’s not as if the indigenous Andeans acquired additional copies of AMY1 when they started eating potatoes. Instead, those who had fewer copies were being eliminated from the population over time, perhaps because had fewer descendantsand those who had the most copies remained.”
Using genetic dating and modeling methods, the researchers then traced the rise of this change. Dating methods showed that the gene was present before potato domestication, but began to increase about 10,000 years ago.
We know that Potato domestication in the Andes began about 10,000 to 6,000 years ago — a timeline that coincides with the increase in the number of copies of the gene that helps digest potatoes.
Nonetheless, other populations descended from the Mayanswithout a long history of potato cultivation, do not present the same adaptation. Therefore, the temporal coincidence is probably not accidental.
“This direct comparison is one of the main reasons why we think that the high AMY1 copy number in Peruvians did not evolve by chancebut it is before linked to its long history of potato consumption”, says the evolutionary geneticist Luane Landaualso a researcher at the University of Buffalo and co-author of the study.
Some scientists have argued convincingly in recent years that Technology is becoming the dominant force in human evolution. This new study presents an interesting dimension to this idea.
In the not too distant past, almost everyone ate, in one way or another, local foods. Today, it is common to eat foods that were directly imported or grown from imported species.
“For most of human history, people ate what their ancestors had eaten for thousands of years. It was literally necessary migrate to another part of the world to change your diet. So what does it mean now that we eat food from all over the world?” asks the evolutionary geneticist Kendra Scheeralso co-author of the study.
“And now that we have shown the forces of natural selection at work from the consumption of potatoes, which means the fact that the whole world eat french fries?” asks the researcher from the University of Buffalo.
