Tibetan women quickly evolved to thrive in low oxygen areas

Imagine, if you can, a place where every breath of air doesn’t quite meet your body’s needs. Yet despite these harsh conditions, Tibetan women residing in the oxygen-poor Tibetan highlands have survived and thrived for over 10,000 years.

This is what you call an art of survival.

Tibetan Survival Code

Credit for solving this mystery goes to a team led by Cynthia Beall, professor emeritus emeritus at Case Western Reserve University.

The study reveals how Tibetan women’s physiological adaptability allows them to reproduce efficiently in such a low-oxygen environment – ​​one that would exhaust most of us in no time.

Beall says these findings not only highlight the impressive resilience of Tibetan women, but also offer valuable insights into how humans might adapt in extreme environments.

This knowledge could potentially guide us in responding to future environmental challenges and shed light on the pathobiology of people suffering from hypoxia-related illnesses (low oxygen levels) at all altitudes.

“Understanding how populations like these adapt allows us to better understand the processes of human evolution,” notes Beall.

Oxygen delivery characteristics in Tibetan

The targeted study included 417 Tibetan women aged 46 to 86, who live between 12,000 and 14,000 feet above sea level in Upper Mustang, Nepal.

The research team of Beall and colleagues collected data on the women’s reproductive history, physiological measures, DNA samples and social factors.

Their goal was to understand how oxygen delivery characteristics in the context of high-altitude hypoxia influence the number of live births – a key metric for measuring evolutionary fitness.

Breathe in clean air

Beall and his team made an interesting discovery. Women who had the most children had unique blood and heart characteristics that improved the efficiency of oxygen delivery to their bodies.

These women reported higher oxygen saturation, leading to efficient delivery of oxygen to cells without increasing the viscosity (thickness) of the blood. And the lower the viscosity of the blood, the less strain on the heart: a rather interesting tip.

“This is a case of ongoing natural selection. Tibetan women have evolved to balance the body’s oxygen needs without overloading the heart,” says Beall.

Tibetan adaptation to lack of oxygen

The remarkable physiological adaptations to low oxygen levels observed in Tibetan women are underpinned by unique genetic variations that have been naturally selected for over millennia.

Studies using genomic analysis have identified particular alleles associated with hemoglobin concentration and efficient oxygen absorption, which are less prevalent in populations residing at lower altitudes.

An important gene, EPAS1, often nicknamed the “superathlete gene,” has been highlighted for its role in the ability of these populations to thrive in low-oxygen environments.

This genetic distinction demonstrates how human populations can evolve distinct biological traits in response to environmental pressures, thereby contributing to our understanding of human genetic diversity and its evolution.

Future research

Understanding these adaptations of Tibetan women to low-oxygen environments not only enriches our understanding of evolutionary biology, but also holds promise for the advancement of medical science.

Knowledge from this research could be key to developing treatments for conditions caused by hypoxia, such as chronic obstructive pulmonary disease (COPD) and certain cardiovascular diseases.

Additionally, the study of genes like EPAS1 could stimulate innovations in improving sports performance or contribute to safe housing in high-altitude regions.

Future research could explore how integrating traditional Tibetan lifestyle practices with genetic predispositions contributes to these adaptive traits, potentially revealing other genetic markers involved in high-altitude survival.

Tibetan evolution and low oxygen levels

In 2019, Beall’s interdisciplinary research team, which includes Brian Hoit and Kingman Strohl of the Case Western Reserve School of Medicine and other U.S. and international researchers, conducted work in the field. They collaborated with local communities in the Nepalese Himalayas and hired local women as research assistants.

The team’s investigation focused on a genetic trait likely inherited from the Denisovans, who lived in Siberia around 50,000 years ago.

The descendants of these Denisovans then migrated to the Tibetan plateau. The trait studied is a variant of the EPAS1 gene, unique to indigenous populations of the Tibetan Plateau. It regulates hemoglobin concentration.

Other features that improve oxygen delivery, such as increased blood flow to the lungs and larger heart ventricles, have also been examined. These traits contributed to greater reproductive success.

Inspiration from Tibetan women

So this is the story of how Tibetan women, with their unique physiological characteristics, are showing us a live demonstration of survival, adaptation and evolution in action over the past 10,000 years, despite the lack of oxygen.

Isn’t it fascinating how the human body can adapt and evolve to survive and thrive with such low oxygen levels? Indeed, it offers a glimpse of evolution in action and the remarkable tenacity of the human spirit.

The study is published in the journal Proceedings of the National Academy of Sciences.

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