"In the 70s, anthropologists started asking 'does everyone in the world adapt in the same way?' Early work showed, no, they don’t."
Beall found that, while natives of the Andes mountains have elevated levels of hemoglobin - the oxygen-carrying molecule - natives of the Tibetan Himalayas don’t. They adapt by increasing their blood-flow.
Beall then found that a lower level of hemoglobin actually correlated with a higher number of successful pregnancies in Tibetans. She wondered if the answer was genetic.
It turns out that Tibetans have a unique version of a gene called EPAS1 that correlates with their low hemoglobin levels, and they’ve traced that gene to an ancient source: "...a fossil population that we only know from a couple of fossil teeth, and their DNA," Beall said.
"Yes, we can trace the origin of this important feature of Tibetan biology nowadays back 50,000 years to the Denisovans in Siberia."
Exploradio Origins is a weekly feature produced in conjunction with the Institute for the Science of Origins at Case Western Reserve University. Tune in to 89.7 WKSU every Thursday afternoon during All Things Considered to listen to Exploradio Origins. You can find each segment posted online after it airs. Explore all the segments here.