The High-Altitude Gene Predominant in the Tibetan People
Updated: Jun 14, 2019
By Lhaden Tshering
When my mother was pregnant with my younger sister, she was having her routine checkups when a doctor discovered that there was something unique about her respiratory system. My mom learned that she has 150% lung capacity, which left her confused and curious as to how she had inherited this characteristic.
Many ethnic groups have physical characteristics that have helped them adapt to the conditions of their environment throughout history. One such example are the Tibetan people, who have spent centuries living at the high altitudes of the Himalayan mountains, a trait that is genetically specific to this group. As a Tibetan, I was curious as to what genotype has allowed past generations of my family to thrive in the low-oxygen level environment of the Himalayas. This gene/allele would also explain how my mom is able to have 150% more lung capacity than someone whose lineage does not trace back to the Tibetan people.
According to a research published in the Journal of High Altitude Medicine and Biology [by Dr. Martha van Patot], the “superathlete” gene that is responsible for Tibetans and Sherpas breathing easy at high altitudes is the gene variant, EPAS1. EPAS1 was originally expressed in the extinct Neanderthal people called the Denisovans. Following the extinction of the Denisovans, the EPAS1 gene was expressed in people of different ethnic backgrounds as the Denisovans mated with ancestors of Europeans and Asians 40,000 years ago. This phenomenon marks the first time in history that a version of a gene acquired from interbreeding with another type of human has been shown to help modern humans adapt to their environment.
A closer look at the immunological effects of variant EPAS1 has revealed that it helps Tibetans use smaller amounts of oxygen efficiently, allowing them to deliver enough of it to their limbs while exercising at high altitude. In particular, EPAS1 regulates the body’s production of hemoglobin. They were surprised, however, by how rapidly the EPAS1 variant spread. The gene has spread through 40% of high-altitude Tibetans in 3000 years, which is the fastest genetic sweep ever observed in humans. Researchers are also shocked by how vastly different the immune response of Tibetans is when compared to other ethnic groups that thrive at high altitude locations, such as the Andean highlanders. Unlike the Tibetan people, Andean highlanders have adapted to such thin air by adding more oxygen-carrying hemoglobin to their blood. Therefore, not only are Tibetans prepared to live in high-altitude environments, but even the means to which their immune systems readjust to a low-oxygen level atmosphere is unique to us/them.
The ability of Tibetans to thrive in high-altitude environments has shaped their way of life. Those who practice Tibetan Buddhism believe in the Buddhist deities, protectors of the Tibetan people and representatives of their ideals. For centuries, Tibetans, including Sherpas - a subgroup of ethnic people who practice Tibetan Buddhism and usually live in Nepal - have seen the mountain ranges as a sacred place where their gods and deities lived. This is because the high-altitude of the mountains was interpreted as the closest point to the heavens. Thus, for decades, Tibetans have climbed the Himalayan mountain range as a way to worship the gods that have brought them good fortune and prosperity, an act that would not be possible if not for the expression of the gene variant EPAS1.
Over time, the ability of Tibetans to work at high-altitudes became embedded into their profession as a majority of Tibetan Buddhists who live near the Himalayas work as mountaineers to guide climbers and tourists up the mountains and make sure that none engage in polluting activities that could anger the gods.