There are over 81.6 million people living above 2,500 meters globally, mostly in Ethiopia, China, Colombia, Peru, and Bolivia. This shows how humans have evolved to adapt to high-altitude situations. These communities display distinctive physiological and genetic adaptations, such as the unique processes present in Ethiopian highlanders, which have important ramifications for comprehending genetic diversity and chronic illnesses and offer insights into human evolution.
Distribution Of The High-Altitude Population
The Ethiopian Highlands, the Andean Altiplano, and the Tibetan Plateau are the three primary places in the world where high-altitude inhabitants are found. The residents of each of these regions have developed distinct genetic adaptations:
About 12.5 million people reside above 2,500 meters on the Tibetan Plateau1. Since they have lived here for almost 3,000 years, Tibetans—including the Sherpa people—have rapidly adapted genetically.
Around 19.5 million people live in the Andean Altiplano, with the largest populations in Bolivia (6.2 million), Peru (7.8 million), and Colombia (11.7 million).1. This area has been inhabited by the Quechua and Aymara for around 11,000 years.
With an estimated 21.7 million people living above 2,500 meters, the Ethiopian Highlands is the most populated high-altitude region. For at least 5,000 years, Ethiopian highlanders have inhabited these altitudes, and some groups have lived above 2,000 meters for as long as 70,000 years.
Because each of these separate communities has evolved special physiological and genetic adaptations to survive in their high-altitude settings, they offer important insights on convergent evolution.
Ethiopian Modifications
Unlike Tibetan and Andean populations, Ethiopian highlanders have evolved special adaptations to high-altitude existence. Ethiopian highlanders do not have elevated hemoglobin levels or notable vascular alterations like their counterparts do. Rather, they sustain elevated arterial oxygen saturation levels, indicating an alternative evolutionary mechanism to adapt to hypoxic environments.
Although research on Ethiopian adaptations to high altitude is still in its infancy, some important conclusions have been drawn:
For at least 5,000 years, Ethiopians have lived above 2,500 meters, and some communities have done so for as long as 70,000 years.
They exhibit distinct genetic markers, especially in the BHLHE41 gene, which controls circadian rhythms and the body’s reaction to hypoxia.
Ethiopians, in contrast to Tibetans, do not exhibit any signs of a Denisovan admixture aiding in their adaption to high altitude.
Ethiopian highlanders’ quick adaptation demonstrates the variety of ways that human populations might change in response to comparable environmental stresses.
These results highlight how crucial it is to investigate a variety of high-altitude groups in order to completely comprehend the variety of adaptive human reactions to hypoxic conditions.
Adaptation Mechanisms In Genetics
Natural selection and gene flow interact intricately in the genetic processes that underlie high-altitude adaption in human populations. A key player in these adaptations is the oxygen regulator known as the Hypoxia Inducible Factor (HIF) pathway, which has been around since the beginning of evolution. Important genes implicated are:
Tibetans and lowlanders differ significantly in the frequency of two genes, EPAS1 and EGLN1, with EPAS1 showing the quickest genetic change of any human gene.
Recently discovered in Tibetans, the genes HYOU1 and HMBS are implicated in heme synthesis and the low oxygen response.
Several genes involved in the HIF pathway: In Andean populations, selection is evident in at least 40 HIF pathway genes.
It’s interesting to note that some adaptive variations might have come from prehistoric hominins. The Tibetan EPAS1 variation, for example, most likely came from Denisovans. The ability of natural selection in harsh circumstances is demonstrated by the Tibetans’ quick adaption, which took place within 3,000 years. These discoveries shed light on the evolutionary history of humans and may help treat disorders linked to hypoxia.
Evolutionary Research Implications
In addition to providing important insights into evolutionary processes, the study of high-altitude adaptations in human communities has wider implications for comprehending human genetic variety and health. Studies in this area have shown:
Rapid evolutionary changes: One of the quickest examples of human evolution that has been documented is the Tibetan adaption, which took place within 3,000 years. This calls into question earlier theories regarding how quickly humans adapt genetically.
Convergent evolution illustrates the variety of human adaption mechanisms by showing how several high-altitude populations have evolved unique genetic responses to comparable environmental stresses.
Archaic admixture: The intricate history of human evolution and interbreeding is highlighted by the finding that certain adaptive variants, such as the Tibetan EPAS1 gene, may have been transmitted from archaic hominins like Denisovans.
Both evolutionary biology and medical research will be significantly impacted by these findings. Gaining knowledge of the genetic underpinnings of high-altitude adaptation may help develop novel therapies for ailments linked to hypoxia and shed light on the genetic components of chronic ischemia illnesses.