Breathing at extreme altitudes presents a major challenge: quite simply, there is less oxygen in each inhalation. However, for over 10,000 years, Tibetan women living on the Tibetan Plateau have managed to not only survive, but thrive in this environment. This is how people are evolving right before our eyes.
A study led by Cynthia Beall, professor of anthropology at Case Western Reserve University (USA), answers some of the questions related to this phenomenon.
Research reveals that humans are evolving right before our eyes: Tibetan women’s physiological traits improve their ability to reproduce in an oxygen-deficient environment.
The study has been published in the magazine Proceedings of the National Academy of Sciences.
The findings, Beall says, underscore not only the remarkable resilience of Tibetan women, but also provide valuable insights into how people can adapt to extreme environments. This type of research also provides clues about human development, how we might respond to future environmental challenges, and the pathobiology of people with hypoxia-related conditions at any altitude.
“Understanding how populations like this adapt gives us a better understanding of the processes of human evolution,” Beall explained.
How women on the Tibetan Plateau manage to breathe at high altitude
Beall and his team studied 417 Tibetan women between the ages of 46 and 86 living at altitudes between 3,658 and 4,267 meters above sea level at a location in Upper Mustang, Nepal, on the southern edge of the Tibetan Plateau .
The researchers collected data on the women’s reproductive history, physiological measurements, DNA samples and social factors. They wanted to understand how oxygen delivery traits under conditions of high-altitude hypoxia (low levels of oxygen in the air and blood) influence the number of live births, a key indicator of evolutionary fitness. Scientists found that women with the most children had a unique set of blood and heart traits that helped the body deliver oxygen, writes Phys.org.
The women who reported the most births had levels of hemoglobin (the molecule that carries oxygen) close to the sample mean, but oxygen saturation was higher, allowing more efficient delivery of oxygen to cells without increasing blood viscosity, which would put pressure on the heart.
“This is a case of continuous natural selection. Tibetan women have evolved in a way that balances the oxygen needs of the body without overtaxing the heart,” Beall said.
Humans are evolving right before our eyes
Beall’s interdisciplinary research team, which included longtime collaborators such as Brian Hoit and Kingman Strohl of Case Western Reserve School of Medicine, conducted the fieldwork in 2019. The team worked closely with local communities in Nepalese Himalayas, employing local women as research assistants and collaborating with community leaders.
One of the genetic traits studied probably comes from the Denisovans, who lived in Siberia about 50,000 years ago; their descendants later migrated to the Tibetan Plateau.
This trait is a variant of the EPAS1 gene, which is unique to the indigenous populations of the Tibetan Plateau and regulates hemoglobin concentration. Other features, such as increased blood flow to the lungs and wider heart ventricles, further improved oxygen delivery.
These traits contributed to greater reproductive success, providing insight into how humans adapt to low oxygen levels throughout life and the process of human evolutionary adaptation.
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Source: www.descopera.ro
