Active human evolution seen alive on the Tibetan Plateau, new study claims

Researchers Find Clear Signs of Active Human Evolution in Nepal (Representational Image: Canva)

Humans still carry stories within their bodies today. Life continues to shape us in slow and quiet ways. High places show this change with unusual clarity. Scientists now ask how people survive air that weakens most visitors. New research offers clues from communities living above the clouds.

What drives adaptation in high altitude regions?
Researchers studied women living across Nepal’s high plateau. Life there sits above 3,500 metres each day. Oxygen levels fall sharply in such harsh air. Most visitors face quick breathlessness and strong headaches. Yet local families raise children and work normally.

Anthropologist Cynthia Beall explained these changes. She spoke to ScienceAlert about her decades of work. She said stress remains equal for everyone there. She added that the conditions make variation easier to study. Her team measured the bodies of 417 Nepalese women. They recorded ages, health markers and total live births.

Which traits link to higher reproductive success?
The women showed wide differences in birth numbers. Some had no children, while others had fourteen. The average number reached 5.2 in the study. Scientists focused on blood traits linked to oxygen delivery. They measured haemoglobin levels and oxygen saturation values.

Women with many births showed a pattern. Their haemoglobin levels stayed around average values. Their oxygen saturation levels stayed noticeably high. This helped avoid thick blood that strains the heart. The finding surprised the research team this year. They found that intermediate haemoglobin gave the best outcome. They also found that higher saturation brought better fitness.

How does blood flow support survival at altitude?
Women with strong reproductive success showed other signs. Their lungs received blood at higher flow rates. Their hearts had wider left ventricles than usual. These features helped push oxygen deeper into tissues. The combination boosted survival chances for mothers and babies.

Cultural factors also shaped birth numbers in many cases. Women who married young gained more years of fertility. Long partnerships increased their chance of childbirth. Yet physical traits still played a major role. Those with bodies similar to low-altitude women had higher success.

Why does this research matter today?
Beall said the findings show natural selection at work. She noted that adaptation continues through daily life. The study appears in the Proceedings of the National Academy of Sciences. It gives a new look at human change today. It may help explain how our species keeps adjusting.