Researchers from the University of California-Berkeley discovered that Tibetans inherited a gene that enabled them to survive in high altitudes when their ancestors interbred with a species of human.
The scientists reported the interbreeding gave Tibetans an unusual gene that helped regulate their body's production of hemoglobin. Hemoglobin is the substance that delivers oxygen to the blood. This gene allowed Tibetans to thrive in altitudes over 150,000 feet. In contrast, most people who go to such levels develop thick blood, have trouble breathing, and develop cardiorespiratory ailments.
"We have very clear evidence that this version of the gene came from Denisovan. This shows very clearly and directly that humans evolved and adapted to new environments by getting their genes from another species." said principal author Rasmus Nielsen, UC Berkeley professor of integrative biology in a university press release.
Denisovans were mysterious human ancestors who lived around 40,000-50,000 years ago.
Scientists dubbed the gene as EPAS 1 and it automatically activates after the body detects a decrease in the amount of oxygen present in the blood. Other researchers called the gene as the superathelete gene because they observed that it helped athletes increase their hemoglobin production at low elevations.
At high altitudes, on the other hand, the gene increases hemoglobin production as well as red blood cells. But, too much production of these will lead to thickness of blood, which may result to heart diseases and hypertension. In babies, the most notable effects are low birth weights and a high rate of infant mortality.
The gene found in the Tibetans was observed to increase the red blood cell and hemoglobin production at a slight manner, preventing the undesirable side effects.
This research was the first study to confirm that there were other species of human beings who contributed to the modern human's survival aptitude in a specific kind of environment.
Further findings of this study were published in the July 2 issue of Nature.
