Tibetans living at high altitudes have evolved ten unique genes to help them to tolerate low oxygen environments without harm. Writing in Science, University of Utah researcher Tatum Simonson, together with colleagues in China, initially identified 247 candidate genes known to be linked to oxygen transport and handling in the body, before comparing the genomes of 31 high-altitude inhabiting Tibetans with some of their lowland-living counterparts. This enabled the team to subtract genes the two groups had in common, leaving ten genes that were clearly different in the Tibetans. The genes they've identified help to explain why Tibetans appear to be resistant to the effects suffered by lowland dwellers who ascend to altitude including excessive haemoglobin levels, blood vessel constriction in the lungs and reduced birth weight. The Tibetans are thought to have developed these unique adaptations, which include enhanced respiratory rates, lower levels of arterial oxygen and increased levels of blood-vessel relaxing hormones, over the 21,000 years since they first took up residence in the region. Understanding these sorts of gene adapatations can be very helpful in the medical setting, commentators point out, because they can inform strategies to treat people with severe lung or heart problems in acute medical settings such as following heart attacks or heart failure, pneumonias or lung injuries.