CLARE CALDWELL: THE ART OF LIVING Have you ever wondered how the Sherpas who toil up and down the world’s highest mountain manage to work and survive in conditions most of us would die in? One of the highest altitude regions on this earth is the Tibetan Plateau, much of which exceeds 4000 metres above sea level. Because the air is thinner at high altitudes, there is less oxygen available to breathe - 40% less in the case of the Tibetan Plateau.
already present (relatives of the Sherpas), who they believe already contained the beneficial EGLN1 and EPAS1 gene versions mentioned earlier. “Acquiring these gene versions helped the newcomers to survive.”
Low oxygen levels can lead to complications in humans and even death, eg, mountain sickness and, in pregnancy and childbirth, a condition called preclampsia. Oxygen is vital for our brains to function normally and thus the rest of our body. People from lower altitudes who have to spend extended amounts of time at a higher altitude have been found to partially adjust to this lack of oxygen by their bodies making more red blood cells, thus capturing more oxygen. But how have Tibetan people whose ancestors have lived on the plateau for at least 30,000 years adapted to being in this low-oxygen environment all the time? It seems there are a number of factors. One of the reasons is found in two particular versions of the genes EGLN1 and EPAS1. All Tibetans have these genes, both of which are involved in sensing and adjusting to oxygen levels. In a paper, www.nature.com/articles/ncomms4281 by Anna Di Rienzo (geneticist), Cynthia Beall (anthropologist), and colleagues published in 2014, they postulated that “Tibetans can trace their ancestry to two previously distinct populations, related to modern Han Chinese and Sherpa.” They then pieced together a sequence of events. By examining the genomes (genetic material present in a cell) of all three living populations - Tibetan, Han Chinese and Sherpa - they discovered people from the lowlands related to the modern Han Chinese, had migrated to higher altitudes where they mixed with those
But here is where it gets interesting. How did the relatives of the Sherpa come to acquire the beneficial versions of their genes in the first place? It seems there was an intervention of another species – the Denisovans, a long extinct cousin of the Neanderthals. The version of the EPAS1 gene associated with high altitude was found in the DNA of the fossilised remains of a Denisovan in a cave in Siberia in 2010. Population geneticist Rasmus Nielson and colleagues deduced from this that the EPAS1 variant made its way into the human gene pool “following a tryst between a modern human and a Denisovan - members of two different species that nonetheless conceived a child who survived and left descendents, some of whom became modern Tibetans.” Amazing! The benefits of mixing genes from differing sources has been a huge part of our human evolution and survival for millennia. I can’t help wondering: what genetic infusion will it take for us to survive the next few millennia and where might it come from? (CLARE CALDWELL) F PN Clare (Claudie) Caldwell is a creative arts therapist who runs a small private practice from home. She currently runs the voluntary art and art as therapy programme at Auckland City Mission. She is also a freelance artist. Enquiries: T: 09 836 3618; M: 021 293 3171; E: clare.e.caldwell@gmail.com
HUNGRY & FEELING THIRSTY? We are spoilt for choice!
THERE ARE NOW 254 PLACES IN THE WESTERN BAYS, WHERE YOU CAN EAT, DRINK AND BE MERRY. They are all listed in the Ponsonby Little Black Book... ponsonbynews.co.nz/ponsonby-little-black-book
62 PONSONBY NEWS+ March 2019
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