Photo: Ethiopian runners train in high altitude. (Selamta Magazine)
Scientists say they have pinpointed genetic changes that allow some Ethiopians to live and work more than a mile and a half above sea level without getting altitude sickness.
The specific genes differ from those reported previously for high-altitude Tibetans, even though both groups cope with low-oxygen in similar physiological ways, the researchers report. If confirmed, the results may help scientists understand why some people are more vulnerable to low blood oxygen levels caused by factors other than altitude — such as asthma, sleep apnea, heart problems or anemia — and point to new ways to treat them, the researchers say.
Living with less
Lower air pressure at high altitude means fewer oxygen molecules for every breath. “At 4000 meters, every lungful of air only has 60% of the oxygen molecules that people at sea level have,” said co-author Cynthia Beall of Case Western Reserve University.
To mop up scarce oxygen from thin air, travelers to high altitude compensate by making more hemoglobin, the oxygen-carrying component of human blood. But high hemoglobin comes with a cost. Over the long term, excessive hemoglobin can increase the risk of blood clots, stroke, and chronic mountain sickness, a disease characterized by thick and viscous blood.
“Altitude affects your thinking, your breathing, and your ability to sleep. But high-altitude natives don’t have these problems,” said Beall, who has studied high altitude adaptation in different populations in Ethiopia, Peru and Tibet for more than 20 years. “They don’t wheeze like we do. Their thinking is fine. They sleep fine. They don’t complain of headaches. They’re able to live a healthy life, and they do it completely comfortably,” she added.
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