Living near the Himalayas, in the Andes or among the arctic ice causes genetic changes that are key to survival.

Tibetans have lived for centuries at an average altitude of 4,900 meters.

With an average altitude of 4,900 meters, Tibet is the highest region on the planet. On its border with Nepal rises Mount Everest, the highest peak above sea level. A few kilometers away, Tibetans have lived for hundreds of years, unaware that their routine in the heights is an evolutionary feat.

“Other people can also reside on the Tibetan plateau but they have a increased incidence of chronic mountain sickness, hypertension, ischemic strokes, and other diseases if they live there permanently, ”Rasmus Nielsen, a researcher at the Department of Statistics at the University of California-Berkeley (USA), who has spent decades studying the genes of this population, lists to EL ESPAÑOL.

Changes in genes allow Tibetans to adapt to heights.

Changes in genes allow Tibetans to adapt to heights.
Woody Wood

The difficulties extend to the descent of non-Tibetan ethnic groups. That is why it is very common for these women to have problems in their pregnancies. “To white, Chinese or Indian people living in Tibet it is very difficult for him to have children with normal health ”, affirms in a telephone conversation with EL ESPAÑOL Josef Prchal, professor of the Department of Internal Medicine at the University of Utah (USA).

Changes in the DNA of Tibetans over the centuries have allowed them to adapt to great heights and compensate for lower oxygen availability that exists at that altitude. Recent genome sequencing of 27 Tibetans has revealed that, in addition to the two known genes involved in this adaptation (EGLN1 and EPAS1), there are three more (PTGIS, VDR and KCTD12).

The ancestors, keys in Tibet

“The Tibetan genome is, in general, very similar to that of other populations, but it has a small proportion of genetic variants present in most Tibetans that are very rare in most of the rest of the worldNielsen highlights. “These genetic variants affect the regulation of red blood cell production,” he adds.

Here a fundamental figure for the Tibetan people comes into play: their ancestors, the Denisovans. This human species, which coexisted with Neanderthals and modern humans, became extinct between 50,000 and 40,000 years ago. Nielsen and his team showed that the EPAS1 gene of the Tibetans was almost identical to that of the Denisovans and very different from that of other humans.

“The Denisovan genes greatly influence in the unusual regulation of red blood cell production in Tibetans, allowing them to live better in the low-oxygen environment of the Tibetan plateau, ”says the scientist. However, this evolutionary advantage can be turned against them when they come down from the heights. According to Prchal, Tibetans who move from Tibet to Kashmir are more likely to suffer from diabetes.

The Eskimo gene for fats

Spread in colder areas, Greenland, northern Canada and Alaska, live the Inuit. These Eskimo peoples that inhabit the Arctic withstand temperatures close to -55ºC, to which are added violent snow storms. In these extreme conditions, food is reduced for most of the year to marine mammals such as seals or whales, which are high in fat.

The Inuit can endure temperatures below -55 ºC.

The Inuit can endure temperatures below -55 ºC.
Ansgar Walk

Anyone who ate these foods over a long period of time would be at high risk for cardiovascular problems, but the Inuit appear to be immune to these diseases. Genes protect them.

“Your diet for thousands of years it has relied heavily on fat, which implies that there were subtle changes in the genes of their ancestors that allowed them to live better in those extreme conditions of cold and diet “, points out Toomas Kivisild, a researcher in human evolutionary genetics at the University of Cambridge (United Kingdom). .

“The frequency of these subtle changes changed dramatically thanks to natural selection,” he adds. This is why the Inuit share practically 100% of their genetic information, even though they live in very remote territories.

An investigation published in Science showed that the Inuit and their Siberian ancestors had mutations in genes involved in fat metabolism, which helps them counteract the harmful effects of such a diet. Mutations were only found in 2% of Europeans and 15% of Han Chinese, populations that were compared in the study.

Genetic changes that protect them from a high-fat diet could be related to high infant mortality.

Genetic changes that protect them from a high-fat diet could be related to high infant mortality.
Ansgar Walk

As with the Tibetans, this evolutionary advantage can work against you. According to a study led by Kivisild, a localized genetic variant in the CPT1A gene, which helps them process fatty diets, also increases the risk of hypoglycemia (low blood sugar). Genetic variation could be related to the high infant mortality of these peoples. “When indigenous populations change their traditional lifestyle and their diet to modern ones, they can become unfit,” the Cambridge researcher shuffles.

In the highlands of Ethiopia

In a completely different environment, in the cradle of humanity, in Africa, populations with exceptional qualities also inhabit. This is the case of the Ethiopians in the highlands, who can live at altitudes of more than 3,500 meters.

In Ethiopia, the inhabitants of the lowlands and highlands present differences in their organism.

In Ethiopia, the inhabitants of the lowlands and highlands present differences in their organism.
Andrea Moroni

As with Tibetans, changes in their genes explain this adaptation. “A small subset of genetic variations makes it physiologically easier for them to live at a high altitude,” Laura Scheinfeldt, a researcher at the Department of Genetics at the University of Pennsylvania (USA), comments to EL ESPAÑOL.

In a study involving the geneticist, scientists analyzed the hemoglobin levels of Ethiopians living in the lowlands and tall and found that they were different from each other. According to scientists, this shows an adaptation of the organism to the altitude.

In the cradle of humanity lives a population with surprising genetic adaptations: the Ethiopians.

In the cradle of humanity lives a population with surprising genetic adaptations: the Ethiopians.
Andrea Moroni

Some of the genes involved in this process were also detected in Tibetan and Andean populations. “Tibetans have genetic changes similar to Andeans who live in the mountains of Bolivia or Peru, and the Ethiopians, but the Tibetans are the ones that have been studied the most ”, Prchal points out.

Genetics in Machu Picchu

The Andean people have also managed to adapt to living among the peaks of the impressive Andes mountain range, which stretches along the western edge of South America, for a total of seven countries.

The Andean communities have managed to adapt to the altitude thanks to their genome.

The Andean communities have managed to adapt to the altitude thanks to their genome.
Andrew Miller

An investigation carried out with fruit flies that were induced to hypoxia – the lack of oxygen that occurs in the heights – concluded that the genetic changes with which they made up for this deficiency were present in both Sherpas and Tibetans, Ethiopians and Andeans.

Andeans, Tibetans, and Ethiopians share genetic similarities.

Andeans, Tibetans, and Ethiopians share genetic similarities.
Federico Racchi

“These results show that, to our surprise, genetic variation in the same types of genes can cause resistance to hypoxia in humans and fruit flies,” explained Kevin White, a researcher at the University of Chicago (USA) and lead author of the study. Thousands of years of evolution and thousands of miles away that have only brought the inhabitants of the two roofs of the planet closer together: the Andean and the Tibetans.