Tibetan women are living proof of how evolution happens on a daily basis

The study identified a genetic trait likely originating from the Denisovans, ancient hominins who lived in Siberia about 50,000 years ago.

In Short

• Researchers collected data on reproductive histories, physiological measurements
• They dried to understand how oxygen delivery traits influence reproductive success
• Women with the most live births possessed a unique set of blood and heart traits

Evolution is a work in progress and ever since the first cells began developing in the oceans, it hasn't stopped.

A new study has now shed light on how evolution is taking shape in one of the most difficult regions for humans to live in - the Tibetan plateau.

Led by Cynthia Beall, Distinguished University Professor Emerita at Case Western Reserve University, the study shows how humans have adapted to thrive in the oxygen-scarce environment of the Tibetan Plateau.

The research, published in the Proceedings of the National Academy of Sciences, offers valuable insights into human evolution and adaptation to extreme environments.

The study examined 417 Tibetan women aged 46 to 86 living at altitudes between 12,000 and 14,000 feet in Upper Mustang, Nepal.

Researchers collected data on reproductive histories, physiological measurements, and DNA samples to understand how oxygen delivery traits influence reproductive success in high-altitude conditions.

Key findings revealed that women with the most live births possessed a unique set of blood and heart traits that enhanced oxygen delivery. These women had near-average hemoglobin levels but higher oxygen saturation, allowing for more efficient oxygen delivery without increasing blood viscosity.

"This is a case of ongoing natural selection," Beall explained. "Tibetan women have evolved in a way that balances the body's oxygen needs without overworking the heart".

The study also identified a genetic trait likely originating from the Denisovans, ancient hominins who lived in Siberia about 50,000 years ago. This trait, a variant of the EPAS1 gene, regulates hemoglobin concentration and is unique to populations indigenous to the Tibetan Plateau.

Other adaptive traits observed included increased blood flow to the lungs and wider heart ventricles, further enhancing oxygen delivery and contributing to greater reproductive success.

This research not only highlights the remarkable resilience of Tibetan women but also provides valuable insights into human adaptation to extreme environments.

The findings offer clues about human development, potential responses to future environmental challenges, and the pathobiology of hypoxia-related illnesses at all altitudes.