Roof of the World

August 9, 2010

Torah Kachur

Science in Seconds On Location:  Torah in Lhasa, Tibet.


Lhasa sits at 3,490m (11,450ft) and is the gateway to the top of the world - the Himalayas.  It is remote, gorgeous and a haven of backpackers who think they are hardcore by going to somewhere so (supposedly) remote and forbidden.  I am one of those backpackers.


It is also home to the Tibetan people - a population so well suited to the altitude that they have genomic modifications that allow them to survive the low oxygen concentrations.  To us lowland dwellers, the decreased oxygen availability causes altitude sickness and supreme laziness.    But, living at high altitudes for any length of time (years) can cause thickening of the blood from increased red blood cell production and has been linked to low birth weights and other adverse effects. 




With such a strong evolutionary pressure for high altitude adaptations, it is no surprise that Tibetans are one of the fastest evolving populations in the world.  One such modification is a different variant, or allele, of the EPAS1 gene.  EPAS1 is a member of the Hypoxia Inducible Factor(HIF) family of genes in the body responsible for regulating other genes in response to low oxygen.  Tibetans survive without increased oxygen in the blood compared to their lowland counterparts, but still manage to receive sufficient oxygen.  Something I am struggling to do right now - I'm practically out of breath from the effort of typing.


It isn't clear how EPAS1 functions or what physiological changes occur because of its activity, but one thing is clear, the Tibetan population are really cool and nice and beautiful.  They have lived at altitude for centuries and might be the only ones who can survive the harshest of environments.



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